ALBERT

Description:    The photoluminescence properties of alkali-earth magnesium silicates (M 2 MgSi 2 O 7 , M=Ca, Sr, and Ba) doped with Eu 2+ were investigated. Solid solutions of Ba x Sr 2− x Si 2 O 7 , Ca 2 MgSi 2 O 7 , and Sr 2 MgSi 2 O 7 were prepared. Ba x Sr 2− x Si 2 O 7 retained a tetragonal crystal structure similar to the structure of the other compounds up to a stoichiometry of x =1.6, which enabled a systematic study of the common structure. Monoclinic Ba 2 MgSi 2 O 7 was prepared, and the luminescence properties were compared with those of other samples. The emission and excitation spectra of tetragonal M 2 MgSi 2 O 7 (M=Ca, Sr, and Ba) changed as a function of the covalency, site symmetry, and crystal field strength. The luminescence properties showed excellent agreement with theoretical predictions based on these factors. The Stokes shift differentiated the emission behaviors of the tetragonal and monoclinic structures. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-4914-z Authors T. Kim, Department of Materials Science and Engineering, Seoul National University, Seoul, 151-742 Republic of Korea Y. Kim, Department of Materials Science and Engineering, Seoul National University, Seoul, 151-742 Republic of Korea S. Kang, Department of Materials Science and Engineering, Seoul National University, Seoul, 151-742 Republic of Korea Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We present a novel approach to extend optical coherence tomography (OCT) to the extreme ultraviolet (XUV) and soft X-ray (SXR) spectral range. With a simple setup based on Fourier-domain OCT and adapted for the application of XUV and SXR broadband radiation, cross-sectional images of semiconductors and organic samples becomes feasible with current synchrotron or laser-plasma sources. For this purpose, broadband XUV radiation is focused onto the sample surface, and the reflected spectrum is recorded by an XUV spectrometer. The proposed method has the particular advantage that the axial spatial resolution only depends on the spectral bandwidth. As a consequence, the theoretical resolution limit of XUV coherence tomography (XCT) is in the order of nanometers, e.g., 3 nm for wavelengths in the water window (280–530 eV). We proved the concept of XCT by calculating the reflectivity of one-dimensional silicon and boron carbide samples containing buried layers and found the expected properties with respect to resolution and penetration depth confirmed. Content Type Journal Article Category Rapid Communication Pages 1-7 DOI 10.1007/s00340-012-4934-8 Authors S. Fuchs, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany A. Blinne, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany C. Rödel, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany U. Zastrau, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany V. Hilbert, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany M. Wünsche, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany J. Bierbach, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany E. Frumker, Joint Laboratory for Attosecond Science, National Research Council of Canada and University of Ottawa, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada E. Förster, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany G. G. Paulus, Institute of Optics and Quantum Electronics, Friedrich-Schiller University of Jena, Max-Wien-Platz 1, 07743 Jena, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Next-generation laser diode arrays with integrated ‘on-chip’ volume holographic gratings can provide high power with spectrally narrowed output that can be tuned about the rubidium D 1 line—without causing significant changes to the laser’s flux or spectral profile. These properties were exploited to independently evaluate the effects of varying the laser centroid wavelength and power on batch-mode Rb/ 129 Xe spin-exchange optical pumping (SEOP) as functions of xenon partial pressure and cell temperature. Locally optimized SEOP was often achieved with the laser tuned to either the red or blue side of the Rb D 1 line; global optimization of SEOP was observed at lower cell temperatures and followed the D 1 absorption profile, which was asymmetrically broadened and red-shifted from the nominal wavelength. The complex dependence of the optimal wavelength for laser excitation on the cell temperature and Xe density appears to result from an interplay between cell illumination and the Rb/ 129 Xe spin-exchange rate, as well as [Xe] cell -dependent changes to the Rb absorption lineshape that are in qualitative agreement with expectations based on previous work [Romalis et al., Phys. Rev. A, 56:4569–4578, ( 1997 )], but significantly greater in magnitude. These next-generation lasers provide a ∼2–3-fold improvement in 129 Xe polarization compared to conventional broadband lasers. Content Type Journal Article Category Invited Paper Pages 1-14 DOI 10.1007/s00340-012-4924-x Authors N. Whiting, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA P. Nikolaou, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA N. A. Eschmann, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA M. J. Barlow, Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, NG7 2RD UK R. Lammert, QPC Lasers Division, Laser Operations LLC, Sylmar, CA 91342, USA J. Ungar, QPC Lasers Division, Laser Operations LLC, Sylmar, CA 91342, USA W. Hu, QPC Lasers Division, Laser Operations LLC, Sylmar, CA 91342, USA L. Vaissie, QPC Lasers Division, Laser Operations LLC, Sylmar, CA 91342, USA B. M. Goodson, Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We theoretically and experimentally investigate the Fraunhofer diffraction pattern of a vortex beam passing through an annular ellipse aperture. It is found that the pattern of the far-field diffraction intensity distribution exhibits some dark spots, which become clearer with increasing the value of the ellipticity factor of the annular ellipse aperture. The diffraction phenomenon is more obvious with increasing the value of the ratio of the inner long axis (or short axis) to the outer side of the annular ellipse aperture. The number of the dark spots in the Fraunhofer diffraction intensity distribution is just equal to the topological charge value of the measured optical vortex, and the centre of each dark spot is just a phase-singularity point. Based on this property, we can measure the topological charge of an optical vortex beam. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-4911-2 Authors H. Tao, College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021, China Y. Liu, College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021, China Z. Chen, College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021, China J. Pu, College of Information Science and Engineering, Institute of Optics and Photonics, Huaqiao University, Xiamen, Fujian 361021, China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Eu 3+ and Sm 3+ co-doped molybdate phosphors have been synthesized via hydrothermal method. The phosphors have the advantages of narrower particle size distribution and regular homogeneous shape. The luminescent properties of the molybdate phosphors were systematically studied. The introduction of Sm 3+ into the red-emitting phosphors can generate a strong excitation line at 405 nm, originating from the 6 H 5/2 → 4 K 11/2 transition of Sm 3+ , significantly extending the excitation region for matching the near-ultraviolet light-emitting diodes (−400 nm). Energy transfer from Sm 3+ to Eu 3+ was observed. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-4916-x Authors X.-j. Geng, School of Materials and Metallurgy, Northeastern University, Shenyang, 110004 P.R. China Y.-w. Tian, School of Materials and Metallurgy, Northeastern University, Shenyang, 110004 P.R. China Y.-j. Chen, College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142 P.R. China L.-j. Xiao, College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142 P.R. China Y. Xie, College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang, 110142 P.R. China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We study pump requirements to produce femtosecond X-ray laser pulses at saturation from inner-shell transitions in the amplified spontaneous emission regime. Since laser-based betatron radiation is considered as the pumping source, we first study the impact of the driving laser power on its intensity. Then we investigate the amplification behavior of the K- α transition of nitrogen at 3.2 nm (395 eV) from radiative transfer calculations coupled with kinetics modeling of the ion population densities. We show that the saturation regime may be experimentally achieved by using PW-class laser-accelerated electron bunches. Finally, we show that this X-ray laser scheme can be extended to heavier atoms and we calculate pump requirements to reach saturation at 1.5 nm (849 eV) from the K- α transition of neon. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-4912-1 Authors M. Ribière, CEA, DAM, GRAMAT, 46500 Gramat, France S. Sebban, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France S. Jacquemot, LULI, Ecole Polytechnique, CEA, UPMC Université Paris VI, 91128 Palaiseau, France B. G. Chéron, CORIA, UMR, CNRS 6614, Saint Etienne du Rouvray, 76801 France K. Ta Phuoc, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France J. Gautier, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France J. Grunenwald, CEA, DAM, GRAMAT, 46500 Gramat, France P. Ribeiro, CEA, DAM, GRAMAT, 46500 Gramat, France M. Kozlova, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France P. Zeitoun, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France A. Rousse, LOA, ENSTA ParisTech, Ecole Polytechnique, UMR CNRS 7639, Chemin de la Hunière, 91761 Palaiseau, France Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The production of ions via laser ablation for the loading of radiofrequency (RF) ion traps is investigated using a nitrogen laser with a maximum pulse energy of 0.17 mJ and a peak intensity of about 250 MW/cm 2 . A time-of-flight mass spectrometer is used to measure the ion yield and the distribution of the charge states. Singly charged ions of elements that are presently considered for the use in optical clocks or quantum logic applications could be produced from metallic samples at a rate of the order of magnitude 10 5 ions per pulse. A linear Paul trap was loaded with Th + ions produced by laser ablation. An overall ion production and trapping efficiency of 10 −7 to 10 −6 was attained. For ions injected individually, a dependence of the capture probability on the phase of the RF field has been predicted. In the experiment this was not observed, presumably because of collective effects within the ablation plume. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-4884-1 Authors K. Zimmermann, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany M. V. Okhapkin, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany O. A. Herrera-Sancho, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany E. Peik, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We have demonstrated proof-of-principle of an incoherent ArF ∗ emission source with a quasi-point emission geometry using a laser-produced plasma in an Ar/F 2 /He/Ne mixed gas. The VUV emission characteristics, such as the emission size, were dependent on those of the plasma-initiating laser. The average emission power was 10 μW at a repetition rate of 10 Hz at 193 nm. The average power conversion efficiency of the 193-nm emission from the plasma-initiating Nd:YAG laser was 6.3×10 −6 . The average emission power at 193 nm was proportional to that of the plasma-initiating laser, indicating the scaling of the emission source. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-4906-z Authors M. Kaku, Department of Electrical and Electronic Engineering and Photon Science Center, University of Miyazaki, Gakuen Kibanadai Nishi 1-1, Miyazaki, 889-2192 Japan Y. Sato, Department of Electrical and Electronic Engineering and Photon Science Center, University of Miyazaki, Gakuen Kibanadai Nishi 1-1, Miyazaki, 889-2192 Japan S. Kubodera, Department of Electrical and Electronic Engineering and Photon Science Center, University of Miyazaki, Gakuen Kibanadai Nishi 1-1, Miyazaki, 889-2192 Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Measurements of 3-pentanone fluorescence quantum yield (FQY) over a wide range of temperatures and pressures in air and nitrogen bath gases are reported and a comprehensive FQY model in support of quantitative planar laser-induced fluorescence diagnostics at elevated pressures and temperatures is presented. Measurements were made of the FQY for 20 mbar of 3-pentanone in nitrogen and air for pressures between 1 and 25 bar in a high-pressure and high-temperature cell for excitation wavelengths of 248, 266, 277, and 308 nm. The measurements were performed in nitrogen from 298 to 745 K and in air from 298 to 567 K. The 3-pentanone FQY data were used to optimize FQY model parameters, including the oxygen and nitrogen quenching rates and vibrational relaxation cascade parameters for nitrogen and oxygen. This work introduces vibrational energy dependence for cascade parameters, as well as a nitrogen quenching rate. The new 3-pentanone FQY model agrees with the measurements within 10%, as well as with fluorescence signal measurements from optical internal combustion engines at pressures and temperatures up to 28 bar and 1100 K. Content Type Journal Article Pages 1-14 DOI 10.1007/s00340-012-4901-4 Authors B. H. Cheung, High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA R. K. Hanson, High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Through the study of photoluminescence spectra, fluorescence decay curves, concentration-dependent luminescence and low temperature luminescence, the energy transfer from isolated group to Yb 3+ is investigated in Yb 3+ doped YP 0.9 V 0.1 O 4 . The experimental results show that the energy transfer from group to Yb 3+ is very efficient. Cooperative energy transfer, through which one high-energy photon absorbed by group is converted to two near-infrared photons emitted by Yb 3+ ions, is proposed to be the energy transfer process. This efficient ultra-violet to near-infrared downconversion could have potential application in improving the efficiency of silicon-based solar cell. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-4892-1 Authors X. T. Wei, Department of Physics, University of Science and Technology of China, Hefei, 230026 China G. Jiang, Department of Physics, University of Science and Technology of China, Hefei, 230026 China K. Deng, Department of Physics, University of Science and Technology of China, Hefei, 230026 China C. Duan, Department of Physics, University of Science and Technology of China, Hefei, 230026 China Y. Chen, Department of Physics, University of Science and Technology of China, Hefei, 230026 China M. Yin, Department of Physics, University of Science and Technology of China, Hefei, 230026 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Ion chains consisting of different species play an important role in new applications in quantum information processing as well as in optical frequency standards. We demonstrate generation and stabilization of ion chains consisting of Ca + and In + . The Ca + chains with In + located at specified positions are synthesized using resonant photo-ionization, real-time imaging and trap field control techniques. A specific configuration of an ion chain is stabilized by destabilizing other configurations via selective excitation of vibrational modes using amplitude modulation on the cooling laser beam. New approaches to an indium ion optical clock are proposed using the ions chains. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-4909-9 Authors K. Hayasaka, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho Nishi-ku, Kobe, 651-2492 Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Raman frequency conversion of high average power pulsed Nd:YAG laser radiation into the near IR spectral region in a barium nitrate Raman laser was studied with the emphasis on thermal effects inside the Raman-active medium. The probe-beam technique together with numerical reconstruction, done by integrating the transient heat conduction and paraxial wave equations, revealed dynamics of the induced distortions featuring high-order optical aberrations. By utilizing the Zernike expansion of the reconstructed phase profile and implementing a special focusing geometry of the pump beam, partial compensation of the distortions was realized in a stable configuration of the Raman cavity. Generation of the first-, second-, and third-order Stokes radiation with output power of 17, 9.5, and 5.5 W corresponding to a quantum conversion efficiency of 32, 21, and 13% is reported. Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-012-4873-4 Authors R. Chulkov, B.I. Stepanov Institute of Physics, National Academy of Science of Belarus, Nesalezhnasti Ave. 68, 220072 Minsk, Belarus V. Lisinetskii, Engineering Physics, University of Applied Sciences Wildau, Bahnhofstr., 1, 15745 Wildau, Germany O. Lux, TU Berlin—Institut für Optik und Atomare Physik, Str.d.17.Juni 135, 10623 Berlin, Germany H. Rhee, TU Berlin—Institut für Optik und Atomare Physik, Str.d.17.Juni 135, 10623 Berlin, Germany S. Schrader, Engineering Physics, University of Applied Sciences Wildau, Bahnhofstr., 1, 15745 Wildau, Germany H. J. Eichler, TU Berlin—Institut für Optik und Atomare Physik, Str.d.17.Juni 135, 10623 Berlin, Germany V. Orlovich, B.I. Stepanov Institute of Physics, National Academy of Science of Belarus, Nesalezhnasti Ave. 68, 220072 Minsk, Belarus Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A silver nanoparticle ensemble was prepared under ultrahigh vacuum (UHV) conditions by Volmer–Weber growth on a quartz substrate for surface-enhanced Raman scattering (SERS) investigations of pyrene molecules. To tune the surface plasmon resonance frequency in the vicinity of the excitation wavelength of 488 nm of the diode laser, the morphology of the silver nanoparticles was optimized. The substrates were mounted in a flow-through cell as part of the optical Raman set-up. A microsystem diode laser generates two slightly different emission wavelengths ( λ =487.61 nm and λ =487.91 nm) with a spectral width 〈10 pm and an optical power of 20 mW, i.e. SERS experiments are possible but also shifted excitation Raman difference spectroscopy (SERDS) can be carried out. For trace analysis of pyrene in water we demonstrate SERS/SERDS experiments which lead to a limit of detection of 2 nmol/l for pyrene. These results suggest that with silver nanoparticle ensembles excited at their plasmon resonance at 488 nm combined SERS/SERDS measurements can be effectively performed for in-situ trace analysis of pollutant chemicals in water. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-011-4866-8 Authors R. Ossig, Institut für Physik and Center for Interdisciplinary Nanostructure Science and Technology—CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany Y.-H. Kwon, Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany F. Hubenthal, Institut für Physik and Center for Interdisciplinary Nanostructure Science and Technology—CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany H.-D. Kronfeldt, Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We describe a method to monitor the distance between two tips of a scanning near-field optical microscope setup. The interaction between the two tips, caused by shear forces and air pressure oscillations between the tips, makes each oscillating tip perform an additional oscillation at the frequency of the other tip. The interaction is detected by analyzing one of the tuning fork signals with a lock-in amplifier locked at the oscillation frequency of the other tuning fork. The resulting signal, called crosstalk, increases sharply only when the scanning tip comes into the immediate vicinity of the stationary one. This effect allows us to prevent the tips from colliding during scanning. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5182-7 Authors A. E. Klein, Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany N. Janunts, Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany A. Tünnermann, Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany T. Pertsch, Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Supercontinuum (SC) generation in a standard telecom fiber using 1 ns pulses of a 1,550-nm DFB laser amplified in a cascade of erbium and erbium/ytterbium fiber amplifiers is reported. The SC source operated at 200 kHz repetition rate and delivered up to 2 W of average output power in the band of 1,300–2,500 nm with a diffraction limited beam. For the wavelengths over 1,650 nm, the output power of 1.1 W was recorded. The spectrum was very flat with the flatness of 〈5 dB in the wavelength interval of 1.6–2.18 μm. To the best of our knowledge, it is the first report on W-level SC generation obtained only in a standard single-mode fiber (SMF-28) with almost the entire spectrum in the eye-safe spectral region (λ 〉 1.4 μm) permitted by silicate glass transparency. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5213-4 Authors Jacek Swiderski, Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw, Poland Maria Maciejewska, Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw, Poland Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We show, for the first time, that step-index silica fibers with a large clad (400 μm core and 720 μm clad) can be used to transmit nanosecond duration pulses in a way that allows reliable (consistent) spark formation in atmospheric pressure air by the focused output light from the fiber. The high intensity (〉100 GW/cm 2 ) of the focused output light is due to the combination of high output power (typical of fibers of this core size) with high output beam quality (better than that typical of fibers of this core size). The high output beam quality, which enables tight focusing, is due to the large clad which suppresses microbending-induced diffusion of modal power to higher order modes owing to the increased rigidity of the core-clad interface. We also show that extending the pulse duration provides a means to increase the delivered pulse energy (〉20 mJ delivered for 50 ns pulses) without causing fiber damage. Based on this ability to deliver high energy sparks, we report the first reliable laser ignition of a natural gas engine including startup under typical procedures using silica fiber optics for pulse delivery. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5189-0 Authors Sachin Joshi, Laser Plasma Diagnostics Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA Nick Wilvert, Laser Plasma Diagnostics Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA Azer P. Yalin, Laser Plasma Diagnostics Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We evaluate the design of Q-switched microchip lasers to examine the limit of their scaling to shorter picosecond pulses. A numerical model based on the laser rate equations is developed and used to predict the output characteristics of prospective laser designs. Based on the modeled results, we employ a SESAM as a passive Q-switch and thin crystals of Nd:YVO 4 as a gain medium to experimentally demonstrate the production of pulses as short as 22 ps. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5223-2 Authors Alex C. Butler, Department of Physics and Astronomy, MQ Photonics Research Centre, Macquarie University, North Ryde, Sydney, NSW 2109, Australia David J. Spence, Department of Physics and Astronomy, MQ Photonics Research Centre, Macquarie University, North Ryde, Sydney, NSW 2109, Australia David W. Coutts, Department of Physics and Astronomy, MQ Photonics Research Centre, Macquarie University, North Ryde, Sydney, NSW 2109, Australia Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Time-resolved detection of field-free molecular alignment is investigated by phase contrast. The technique based on a 4 f imager operating as an inverted Zernike spatial filter makes it possible to discriminate between positive and negative molecular alignment revivals produced in a linear molecule. The measurements are performed in a way that minimizes the contamination of the signal by the plasma generated during the aligning pulse. The observations are supported by a semi-analytical model, from which the degree of alignment produced at the beam focus is estimated. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5203-6 Authors J. Houzet, Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon Cedex, France F. Billard, Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon Cedex, France E. Hertz, Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon Cedex, France D. Chateau, Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon Cedex, France F. Chaussard, Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon Cedex, France B. Lavorel, Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon Cedex, France O. Faucher, Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon Cedex, France Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We experimentally demonstrate the writing of soliton waveguides in lithium niobate with blue violet light, at λ  = 405 nm. This wavelength, obtained from a low-cost laser diode, allows very fast writing of soliton waveguides when comparing with the writing process using green light (532 nm). For the same writing time, there is a decrease of ~4 orders of magnitude of the light intensity necessary for writing soliton waveguides in blue. The writing process is investigated and characterized by tuning parameters, such as beam intensity, external field and beam polarization. The IR guiding capability of these soliton waveguides is tested by guiding femtosecond laser pulses at λ  = 1,550 nm. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-5202-7 Authors S. T. Popescu, National Institute for Laser, Plasma and Radiation Physics, Bucharest, Magurele, 077125 Romania A. Petris, National Institute for Laser, Plasma and Radiation Physics, Bucharest, Magurele, 077125 Romania V. I. Vlad, National Institute for Laser, Plasma and Radiation Physics, Bucharest, Magurele, 077125 Romania Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A Faraday isolator system with external compensation of thermally induced birefringence was investigated for the case when optical components of the Faraday isolator and the compensator are made of different materials. Simultaneous reduction of thermally induced depolarization and thermal lens in the Faraday isolator based on a TGG crystal was demonstrated experimentally for the first time using an Sm:CaF 2 crystal. A method of compensating thermally induced birefringence without reciprocal polarization rotator was described theoretically and demonstrated in experiments for the first time. It was used as a basis for a new scheme of Faraday isolator with external compensation of thermally induced birefringence. Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-012-5183-6 Authors Ilya L. Snetkov, Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Street, 603950 Nizhny Novgorod, Russia Oleg V. Palashov, Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Street, 603950 Nizhny Novgorod, Russia Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We report on the generation of tunable light around 400 nm by frequency-doubling ultrashort laser pulses whose spectral phase is modulated by a sum of sinusoidal functions. The linewidth of the ultraviolet band produced is narrower than 1 nm, in contrast to the 12 nm linewidth of the non-modulated incident spectrum. The influence of pixellation of the liquid crystal spatial light modulator on the efficiency of the phase-modulated second harmonic generation is discussed. Content Type Journal Article Category Rapid Communication Pages 1-5 DOI 10.1007/s00340-012-5181-8 Authors J. P. Siqueira, Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, São Carlos, SP 13560-970, Brazil A. R. de Oliveira, Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, São Carlos, SP 13560-970, Brazil L. Misoguti, Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, São Carlos, SP 13560-970, Brazil S. C. Zilio, Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, São Carlos, SP 13560-970, Brazil Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We demonstrated the lasing of Ne-like Ar 46.9 nm pumped by capillary discharge with the delay time between pre-pulse and main-pulse ranging from 2 to 130 μs. Results show that the laser output reduced significantly when the delay time is much longer than 12 μs. The temporal evolution of spontaneous radiation emitted from pre-ionized plasma implies that the observed reduction of the laser output is caused by the axial non-uniformity of pre-ionized plasma density and the decrease of pre-ionized plasma density. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-5190-7 Authors Shan Jiang, National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin, 150080 Heilongjiang, China Yong-peng Zhao, National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin, 150080 Heilongjiang, China Yao Xie, State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 Jilin, China Miao Xu, National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin, 150080 Heilongjiang, China Huai-yu Cui, National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin, 150080 Heilongjiang, China Han Wu, National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin, 150080 Heilongjiang, China Yang Liu, National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin, 150080 Heilongjiang, China Qiang Xu, National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin, 150080 Heilongjiang, China Qi Wang, National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin, 150080 Heilongjiang, China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A passive mode-locked fiber laser-delivered 13 ps pulse is saturatedly amplified with a four-stage amplifier chain. 125 W high power all-fiber picoseconds pulse laser is demonstrated in a 15-μm fiber core, and the optical-to-optical conversion efficiency of the main amplifier is up to 86.12 %. A home-made (6 + 1) × 1 fiber combiner is used to couple the pump light and signal light into the gain double cladding fiber. In order to suppress the nonlinear effects in high-power picosecond fiber amplifiers, the repetition rate of the seed pulse is increased from 60 MHz to ~1 GHz; also the gain fibers are advisably selected. The amplified output spectrum is symmetrically broadened to several nanometers due to self-phase modulation (SPM). No stimulated Raman scattering (SRS), amplified spontaneous emission (ASE) and residual pump light are observed and the optical signal-to-noise ratio is more than 30 dB. The all-fiber picoseconds MOPA laser in this report can be easily performed with the conventional fiber handing equipments, and it has great potential to be applied as pump source in the fields of optical parametric oscillator, laser frequency-doubling and supercontinuum generation. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5119-1 Authors H. W. Chen, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 People’s Republic of China Y. Lei, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 People’s Republic of China S. P. Chen, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 People’s Republic of China J. Hou, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 People’s Republic of China Q. S. Lu, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 People’s Republic of China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Continuous-wave (CW) and passively Q-switching laser performance of the Yb:CNGG and Yb:CLNGG disordered garnet crystals are compared. CW output powers of 6.3 and 7.5 W are generated from the Yb:CNGG and Yb:CLNGG lasers, with slope efficiencies measured to be 63 and 74 %, respectively. In passively Q-switched operation, the average output power reaches 2.0 and 3.1 W, with slope efficiencies of 56 and 65 %, for the Yb:CNGG and Yb:CLNGG lasers, respectively. Laser pulses of 9.5 ns in duration are generated with the two Yb lasers, with the highest pulse energy and peak power amounting to 166.7 μJ and 17.5 kW for the Yb:CNGG laser, and 133.0 μJ and 14.0 kW for the Yb:CLNGG laser. In respects of efficient laser operation and power scaling, the Yb:CLNGG proves to be advantageous over Yb:CNGG, whereas the Yb:CNGG is superior to Yb:CLNGG in energy storage capacity. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5212-5 Authors Junhai Liu, College of Physics, Qingdao University, Ning-Xia Road 308, Qingdao, 266071 China Yong Wan, College of Physics, Qingdao University, Ning-Xia Road 308, Qingdao, 266071 China Zhichao Zhou, College of Physics, Qingdao University, Ning-Xia Road 308, Qingdao, 266071 China Xueping Tian, College of Physics, Qingdao University, Ning-Xia Road 308, Qingdao, 266071 China Wenjuan Han, College of Physics, Qingdao University, Ning-Xia Road 308, Qingdao, 266071 China Huaijin Zhang, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The formation and evolution of laser-induced post-solitons in near-critical density plasma are studied using the two-dimensional theoretical model and particle in cell simulation. The study shows that a considerable part of laser energy can penetrate plasma, which is then trapped in an empty cavity bounded by overdense plasma peaks. The self-trapped electromagnetic fields remain as a half-cycle standing wave. The amplitude of these electromagnetic fields peaks at the cavity center and vanishes at the boundary. As the cavity expands slowly, the field amplitude decreases, and the oscillation frequency is reduced to merely a small faction of laser frequency. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5140-4 Authors Shixia Luan, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800 China Wei Yu, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800 China Wenwu Xu, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, 116023 China Masakatsu Murakami, Institute of Laser Engineering, Osaka University, Osaka, 565-0871 Japan Hongbin Zhuo, College of Science, National University of Defense Technology, Changsha, 410073 China Jingwei Wang, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800 China Xin Wang, Rice University, Houston, TX 77005-1892, USA Huichun Wu, Los Alamos National Laboratory, Los Alamos, NM 87545, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    In this work, we investigate experimentally and theoretically limitations of highly efficient high-power single-pass second-harmonic generation process in a quasi-phase matched magnesium oxide-doped lithium niobate ridge waveguide due to structural imperfections, optical absorption and resulting heat generation. With the distributed Bragg reflector diode laser emitting at 1,061 nm, applied in the presented bench-top experiment, a coupling efficiency into the ridge waveguide nonlinear device of 86 % is realized. An internal normalized conversion efficiency of 375 % (Wcm 2 ) - 1 is determined. A maximum second-harmonic power of 386 mW is reached at a corresponding opto-optical and electro-optical conversion efficiency of 38 and 9.5 %, respectively. A saturation of the conversion efficiency at a high power level as well as its dependency on the nonlinear device structure inhomogeneity are confirmed experimentally. With a theoretical model incorporating geometrical inhomogeneity, linear and nonlinear absorption and resulting heat load the second-harmonic generation in a ridge waveguide can be simulated realistically. Increased values of nonlinear absorption coefficients, higher than until now reported, lead to a very good agreement between theoretical and experimental results. Moreover, according to the simulation, structural inhomogeneities can enhance the SHG conversion efficiency at high output powers. Content Type Journal Article Pages 1-10 DOI 10.1007/s00340-012-5184-5 Authors Daniel Jedrzejczyk, Ferdinand-Braun-Institut, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany Reiner Güther, Ferdinand-Braun-Institut, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany Katrin Paschke, Ferdinand-Braun-Institut, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany Götz Erbert, Ferdinand-Braun-Institut, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany Günther Tränkle, Ferdinand-Braun-Institut, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We report on studies on the light-shift in caesium miniature atomic clocks based on coherent population trapping (CPT) using a micro-fabricated buffer-gas cell (MEMS cell). The CPT signal is observed on the Cs D1-line by coupling the two hyperfine ground-state Zeeman sublevels involved in the clock transition to a common excited state, using two coherent electromagnetic fields. These light fields are created with a distributed feedback laser and an electro-optical modulator. We study the light-shift phenomena at different cell temperatures and laser wavelengths around 894.6 nm. By adjusting the cell temperature, conditions are identified where a miniature CPT atomic clock can be operated with simultaneously low temperature coefficient and suppressed light-shift. The impact of the light-shift on the clock frequency stability is evaluated. These results are relevant for improving the long-term frequency stability of CPT-based Cs vapour-cell clocks. Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-012-5121-7 Authors D. Miletic, Laboratoire Temps-Fréquence (LTF), Institut de Physique, Université de Neuchâtel, Avenue de Bellevaux 51, 2000 Neuchâtel, Switzerland C. Affolderbach, Laboratoire Temps-Fréquence (LTF), Institut de Physique, Université de Neuchâtel, Avenue de Bellevaux 51, 2000 Neuchâtel, Switzerland M. Hasegawa, FEMTO-ST, CNRS et Université de Franche-Comté, 32 avenue de l’observatoire, 25044 Besançon cedax, France R. Boudot, FEMTO-ST, CNRS et Université de Franche-Comté, 32 avenue de l’observatoire, 25044 Besançon cedax, France C. Gorecki, FEMTO-ST, CNRS et Université de Franche-Comté, 32 avenue de l’observatoire, 25044 Besançon cedax, France G. Mileti, Laboratoire Temps-Fréquence (LTF), Institut de Physique, Université de Neuchâtel, Avenue de Bellevaux 51, 2000 Neuchâtel, Switzerland Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We demonstrate laser nitrogen isotope separation, which is based on field-free alignment and angular-dependent ionization of 14 N 2 and 15 N 2 isotopologues. A linearly polarized short laser pulse ( λ  ~ 795 nm, Δ τ  ~ 60 fs) creates rotational wave packets in the isotopologues, which periodically revive with different revival times as a result of different moments of inertia. Another linearly polarized short laser pulse ( λ  ~ 795 nm, Δ τ  ~ 60 fs) ionizes one of the isotopologues selectively as a result of their different angular distributions. In the present experiments, the ion yield ratio R [= I ( 15 N 2 + )/ I ( 14 N 2 + )] can be changed in the range from 0.85 to 1.22, depending on the time delay between the two laser pulses. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5222-3 Authors Hiroshi Akagi, Quantum Beam Science Directorate, Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan Tatsuya Kasajima, Quantum Beam Science Directorate, Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan Takayuki Kumada, Quantum Beam Science Directorate, Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan Ryuji Itakura, Quantum Beam Science Directorate, Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan Atsushi Yokoyama, Quantum Beam Science Directorate, Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan Hirokazu Hasegawa, Department of Integrated Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo, 153-8902 Japan Yasuhiro Ohshima, Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki, 444-8585 Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Nanosize three-dimensional (3D) dark spots with a light shell in enhanced local optical fields generated by a plasmonic metal-coated conical dielectric probe with a nano-rod are investigated numerically. The 3D dark spots are due to interference among plasmon-enhanced local fields. It is found that two kinds of 3D dark spots are generated in the free space in the vicinity of the nano-rod. One is generated near the rod end and has a disk shape. The other is generated around the nano-rod and has a toroidal shape. Both kinds of 3D dark spots have nanoscale dimensions, because they are generated by interference between near fields. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5217-0 Authors Kazuo Tanaka, Department of Electronics and Computer Engineering, Gifu University, Yanagido 1-1, Gifu City, 501-1193 Japan Kiyofumi Katayama, Faculty of Administration and Informatics, University of Hamamatsu, Hamamatsu City, 431-2102 Japan Masahiro Tanaka, Department of Electronics and Computer Engineering, Gifu University, Yanagido 1-1, Gifu City, 501-1193 Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A new method for gain and noise figure enhancements in S-band thulium-doped fiber amplifier (TDFA) co-doped with aluminum is demonstrated using a macro-bending approach. The macro-bending suppresses both the amplified spontaneous emission (ASE) at 800 and 1,800 nm wavelength region and consequently improves the S-band gain of the TDFA. Gain enhancements between 5 and 8 dB are obtained with the macro-bending between 1,420 and 1,480 nm. The macro-bending also reduces the noise figure of the S-band TDFA. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-5216-1 Authors S. D. Emami, Department of Electrical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia H. A. Abdul-Rashid, Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Malaysia S. Z. M. Yasin, Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Malaysia K. A. M. Shariff, Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Malaysia S. E. Mirnia, Department of Electrical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia A. Parvizi, Department of Electrical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia H. Ahmad, Photonics Research Center, University of Malaya, 50603 Kuala Lumpur, Malaysia S. W. Harun, Department of Electrical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We report on a compact high-efficiency Cs slow atom beam source based on a retro-reflected two-dimensional magneto-optical trap (2D MOT). Employing two laser beams in an angled retro-reflected setup, we achieve 3D MOT loading rates greater than 8 × 10 9  atoms/s using only 20 mW of total laser power for the source. Content Type Journal Article Pages 1-4 DOI 10.1007/s00340-012-5220-5 Authors James R. Kellogg, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA Dennis Schlippert, Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany James M. Kohel, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA Robert J. Thompson, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA David C. Aveline, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA Nan Yu, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We report experimental generation of a partially coherent Laguerre–Gaussian beam with mode orders 0 and l (i.e., LG 0 l beam) using a rotating ground-glass plate and a spatial light modulator. Focusing properties of the generated beam are studied both theoretically and experimentally. It is found that the focused intensity of the LG 0 l beam is shaped through varying the initial spatial coherence, and our experimental results agree well with the theoretical predictions. Our results will be useful in particle trapping and free-space optical communications. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5209-0 Authors Chengliang Zhao, School of Physical Science and Technology, Soochow University, Suzhou, 215006 China Yuan Dong, School of Physical Science and Technology, Soochow University, Suzhou, 215006 China Yuming Wang, School of Physical Science and Technology, Soochow University, Suzhou, 215006 China Fei Wang, School of Physical Science and Technology, Soochow University, Suzhou, 215006 China Yongtao Zhang, School of Physical Science and Technology, Soochow University, Suzhou, 215006 China Yangjian Cai, School of Physical Science and Technology, Soochow University, Suzhou, 215006 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A new procedure with minimum sample preparation has been developed for a fast and serial analysis of cryolite with varying concentrations of dissolved alumina by liquid-phase laser ablation followed by Total Reflection X-Ray Fluorescence and induced coupled plasma optical emission spectroscopy. The analysis supplies the sodium/aluminium ratio of bath samples taken from industrial Hall-Herault reduction cells, as well as trace element relative concentrations. Two different types of molten samples taken directly from the aluminium production plant were placed under distilled de-ionized water in a quartz cell and subjected to pulsed laser ablation using the beam from a third harmonic Nd:YAG laser. Scanning electron microscopy examination shows the nanoparticles nature of the ablated material. The water-suspension is deposited on quartz reflectors for Total Reflection X-ray Fluorescence analysis or directly aspirated to the induced coupled plasma yielding the aluminium and sodium signals. Instrument quantification of the elements is performed by the use of aqueous standards. Validation tests were done with cryolite sample digestion and standard methods of sample quantification. The procedure can provide the aluminium/sodium ratio with adequate precision for aluminium production plant cell diagnostics and reveals the trace elements that could be considered as contamination. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-5175-6 Authors Ricardo Castell, Universidad Simon Bolivar, Apartado 89000, Caracas, 1080 Venezuela Eduardo D. Greaves, Universidad Simon Bolivar, Apartado 89000, Caracas, 1080 Venezuela Lyzeth Abdala, Universidad Simon Bolivar, Apartado 89000, Caracas, 1080 Venezuela Haydn Barros, Universidad Simon Bolivar, Apartado 89000, Caracas, 1080 Venezuela Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Analytical expressions for the components of the nonparaxial propagation a Lorentz-Gauss vortex beam in uniaxial crystals orthogonal to the optical axis are derived. The intensity and the phase distributions of the components of a Lorentz-Gauss vortex beam propagating in a uniaxial crystal orthogonal to the optical axis are shown by numerical examples. Even though one of the two transversal components of a Lorentz-Gauss vortex beam in the source plane is equal to zero, it emerges upon propagation inside the uniaxial crystal. Moreover, the beam profile of a Lorentz-Gauss vortex beam in the uniaxial crystal becomes twisted and tilted. The three components are completely different and have their respective evolution laws. The intensity distribution and the phase distribution of a Lorentz-Gauss vortex beam can be modulated by the uniaxial crystal, which is beneficial to the optical trapping and nonlinear optics involving in the special beam profile. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5118-2 Authors Yongzhou Ni, School of Sciences, Zhejiang A & F University, Lin’an, 311300 Zhejiang Province, China Guoquan Zhou, School of Sciences, Zhejiang A & F University, Lin’an, 311300 Zhejiang Province, China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Temporally resolved observation of microscopic structural dynamics of solids with ultrafast electron diffraction (UED) requires extremely short pulsed, highly charged, monoenergetic electron beams with sufficient transverse coherence length of several unit cells of the investigated samples. However, Coulomb repulsion defeats these parameters in free propagation of an electron pulse initially bright on the photo cathode. We demonstrate a new electron pulse compressor design based on a simple and compact RF structure incorporating a pair of gallium arsenide photoconductive semiconductor switches that are triggered by femtosecond laser pulses, thereby providing a longitudinal voltage gradient of up to 20 V/ps. Our proof of principle experiment achieved compression of bunches containing 26,000 electrons to a duration of below 750 fs and a beam diameter of 300 μm in the temporal and spatial focus of the device while maintaining the good beam collimation required for time resolved electron diffraction experiments. The simplicity of the compressor provides a strong incentive for its further development toward practical implementation in sub-relativistic UED experiments requiring the highest possible source brightness. Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-012-5207-2 Authors G. H. Kassier, Physics Department, Laser Research Institute, Stellenbosch University, Stellenbosch, South Africa N. Erasmus, Physics Department, Laser Research Institute, Stellenbosch University, Stellenbosch, South Africa K. Haupt, Physics Department, Laser Research Institute, Stellenbosch University, Stellenbosch, South Africa I. Boshoff, Physics Department, Laser Research Institute, Stellenbosch University, Stellenbosch, South Africa R. Siegmund, Physics Department, Laser Research Institute, Stellenbosch University, Stellenbosch, South Africa S. M. M. Coelho, Department of Physics, University of Pretoria, Pretoria, 0002 South Africa H. Schwoerer, Physics Department, Laser Research Institute, Stellenbosch University, Stellenbosch, South Africa Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We theoretically investigated the generation of quantum-correlated photon pair through spontaneous four-wave mixing in tellurite microstructured optical fiber (MOF). We evaluated the performance of photon pair generation in tellurite fibers based on Raman gain coefficient spectra. It was shown that the TBSN16P6W tellurite fiber provided a low Raman noise on correlation photon generation over a wide pump-idler detuning range. We can choose proper tellurite composition to obtain a low Raman gain window over wide range for correlated photon pair generation. We also designed the tellurite MOF structure to obtain a small dispersion value with high nonlinear coefficient at telecommunication wavelengths, thus realize efficient quantum-correlated photon pair generation. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5200-9 Authors Xin Yan, Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Nagoya, Tempaku 468-8511, Japan Meisong Liao, Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Nagoya, Tempaku 468-8511, Japan Tong Hoang Tuan, Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Nagoya, Tempaku 468-8511, Japan Takenobu Suzuki, Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Nagoya, Tempaku 468-8511, Japan Yasutake Ohishi, Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Nagoya, Tempaku 468-8511, Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    An analytical expression of an Airy beam passing through a fractional Fourier transform (FRFT) system is presented. The effective beam size of the Airy beam in the FRFT plane is also derived. The influences of the order of FRFT, the modulation parameter, and the transverse scale on the normalized intensity distribution and the effective beam size of an Airy beam in the FRFT plane are examined. The order of FRFT controls the effective beam size and the orientation of the beam spot. The modulation parameter affects the effective beam size and the number of lateral side lobes. The normalized intensity distribution and the effective beam size are both proportional to the transverse scale. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5117-3 Authors Guoquan Zhou, School of Sciences, Zhejiang A and F University, Lin’an, Hangzhou, 311300 Zhejiang Province, China Ruipin Chen, School of Sciences, Zhejiang A and F University, Lin’an, Hangzhou, 311300 Zhejiang Province, China Xiuxiang Chu, School of Sciences, Zhejiang A and F University, Lin’an, Hangzhou, 311300 Zhejiang Province, China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    This study addresses the initiation of laser-induced breakdown of dielectric materials in the nanosecond regime under multi-wavelength conditions. In particular, the competition between multi-photon absorption and electronic avalanche as ionization mechanisms in KDP crystal is studied. Since they are both dependent on the laser frequency and intensity of incident radiations, we carried out two experiments: in mono-wavelength configuration at 1,064 nm and in multi-wavelengths configuration applying the simultaneous mixing of 1,064 and 355 nm radiations with various fluence ratios. To interpret experimental data, a model based on heat transfer and which includes ionization processes has been developed for both configurations. The comparison between experiments and modeling results first indicates that avalanche can be responsible for optical breakdown at 1,064 nm. Then, the study underlines the existence of a coupling effect in the multi-wavelength configuration where multi-photon absorption and electronic avalanche both contribute to the breakdown. From a general point of view, the model accounts for the experimental trends and particularly reveals that the electronic recombination timescale may have an important role in the scenario of nanosecond laser-induced breakdown. Content Type Journal Article Pages 1-12 DOI 10.1007/s00340-012-5238-8 Authors S. Reyné, CEA-Cesta, 15 Avenue des Sablières, 33114 Le Barp, France G. Duchateau, CELIA, UMR-5107 Université Bordeaux I-CNRS-CEA, 351 Cours de la libération, 33405 Talence, France J. Y. Natoli, Institut Fresnel, UMR-CNRS 6133, D.U. St Jérôme, 13397 Marseille, France L. Lamaignère, CEA-Cesta, 15 Avenue des Sablières, 33114 Le Barp, France Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    In this work, we demonstrate for the first time that it is possible to transfer simultaneously an ultra-stable optical frequency and precise and accurate timing over 540 km using a public telecommunication optical fiber network with Internet data. The optical phase is used to carry both the frequency information and the timestamps by modulating a very narrow optical carrier at 1.55 μm with spread spectrum signals using two-way satellite time transfer modems. The results in terms of absolute time accuracy (250 ps) and long-term timing stability (20 ps) well outperform the conventional Global Navigation Satellite System or geostationary transfer methods. Content Type Journal Article Category Rapid Communication Pages 1-4 DOI 10.1007/s00340-012-5241-0 Authors Olivier Lopez, Laboratoire de Physique des Lasers, Université Paris 13, Sorbonne Paris Cité, CNRS, 99 Avenue Jean-Baptiste Clément, 93430 Villetaneuse, France Amale Kanj, LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 Av. de l’Observatoire, 75014 Paris, France Paul-Eric Pottie, LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 Av. de l’Observatoire, 75014 Paris, France Daniele Rovera, LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 Av. de l’Observatoire, 75014 Paris, France Joseph Achkar, LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 Av. de l’Observatoire, 75014 Paris, France Christian Chardonnet, Laboratoire de Physique des Lasers, Université Paris 13, Sorbonne Paris Cité, CNRS, 99 Avenue Jean-Baptiste Clément, 93430 Villetaneuse, France Anne Amy-Klein, Laboratoire de Physique des Lasers, Université Paris 13, Sorbonne Paris Cité, CNRS, 99 Avenue Jean-Baptiste Clément, 93430 Villetaneuse, France Giorgio Santarelli, LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 Av. de l’Observatoire, 75014 Paris, France Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Quartz-enhanced photoacoustic spectroscopy (QEPAS) is demonstrated for acetylene detection at atmospheric pressure and room temperature with a fiber-coupled distributed feedback (DFB) diode laser operating at ~1.53 μm. An efficient approach for gas concentration calibration is demonstrated. The effect of residual amplitude modulation on the performance of wavelength modulated QEPAS is investigated theoretically and experimentally. With optimized spectrophone parameters and modulation depth, a minimum detectable limit (1 σ ) of ~2 part-per-million volume (ppmv) was achieved with an 8.44-mW diode laser, which corresponds to a normalized noise equivalent coefficient (1 σ ) of 6.16 × 10 −8  cm −1  W/Hz 1/2 . Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5221-4 Authors Y. Cao, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong, China W. Jin, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong, China H. L. Ho, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong, China L. Qi, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong, China Y. H. Yang, Department of Opto-electronics Engineering, School of Instrument Science and Opto-electronics Engineering, BeiHang University, Beijing, 100191 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We have investigated the spectral dispersion of second molecular hyperpolarizability γ (− ω ′; ω , − ω , ω ) of three derivatives of heteroarylene methine by antiresonant ring interferometric nonlinear spectroscopic technique using femtosecond modelocked Ti:sapphire laser in the spectral range of 725–820 nm. The observed dispersion of γ has been explained in the framework of three-essential states model involving the ground state, a one-photon excited state and a two-photon excited state. The spectral response of the hyperpolarizability has been correlated with the electronic and chemical structures of the three derivatives of heteroarylene methine. The estimated γ values have been compared to the fundamental quantum mechanical limit. We have found for the first time that the heteroarylene methines approach this limit within a factor of 2 while even the best known molecule so far falls short of this limit by a factor of 30. Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-012-5199-y Authors B. Bhushan, Department of Physics, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076 India S. K. Kumar, Department of Chemistry, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076 India S. S. Talwar, Department of Chemistry, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076 India T. Kundu, Department of Physics, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076 India B. P. Singh, Department of Physics, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076 India Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    N-ZnO/Ga 2 O 3 / p -GaN heterojunction light-emitting diode (LED) was fabricated by metal-organic chemical vapor deposition. Compared with the n -ZnO/ p -GaN structure, the deep level visible emission at 525 nm was completely suppressed while UV emission at ~392 nm was significantly improved in ZnO/Ga 2 O 3 / p -GaN structure. The role of Ga 2 O 3 in n -ZnO/Ga 2 O 3 / p -GaN heterojunction LED was discussed in detail. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5219-y Authors Yuanda Liu, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 China Hongwei Liang, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 China Xiaochuan Xia, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 China Rensheng Shen, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 China Yang Liu, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 China Jiming Bian, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 China Guotong Du, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    According to the recent calculations, more efficient THz pulse generation is possible using relief grating on the front surface of the generating LiNbO 3 (LN) crystal for tilted-pulse-front-excitation rather than imaging the pump spot on a reflection grating into the LN crystal. Very recently, it was shown that—compared to a free-standing LN surface-relief grating—significantly higher diffraction efficiency can be reached if the grating profiles are filled with fused silica. Since realisation of such a setup is technically very challenging, in the present paper, we analyse the case where the input side of the LN grating is immersed into a refractive index matching liquid (RIML) instead of a solid material. Our results showed that the diffraction efficiency remains above 90 % for a refractive index ranging 1.45–1.60 of the applied RIML, and it is as high as 99 % for using the RIML for BK7. For this case, we carried out detailed calculations for various grating parameters. We propose a practical setup applying tilted input and slightly tilted output surfaces resulting in low losses and high diffraction efficiency for the pump. We conclude that a contact grating setup using BK7 RIML is suitable for producing THz pulses even in the mJ-energy range. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5201-8 Authors Zoltán Ollmann, Institute of Physics, University of Pécs, Ifjúság ú. 6, 7624 Pécs, Hungary János Hebling, Institute of Physics, University of Pécs, Ifjúság ú. 6, 7624 Pécs, Hungary Gábor Almási, Institute of Physics, University of Pécs, Ifjúság ú. 6, 7624 Pécs, Hungary Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The present study develops and investigates for the first time a unique spatial continuously tunable cone laser based on a dye-doped cholesteric liquid crystal (DDCLC) film with an LC-birefringence (Δ n ) gradient. A continuous Δ n variation can be generated in a cell by diffusion and self-organization of CLC after four DDCLC mixtures with a discrete variation of Δ n are successively injected into an empty cell. Not only the CLC photonic structure but also the lasing wavelength and the cone angle of the obtained conically symmetric emitted lasing ring can be tuned continuously by continuously changing the pumped position of the cell with an Δ n gradient. The continuous tunabilities in the lasing wavelength and the corresponding emitted cone angle of the lasing ring are 605.8 → 568.1 nm and 29° → 50°, respectively, within a spatial interval of about 33 mm in the cell. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5218-z Authors Chia-Rong Lee, Department of Photonics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, 701 Taiwan Shih-Hung Lin, Department of Photonics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, 701 Taiwan Jia-De Lin, Department of Photonics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, 701 Taiwan Ting-Shan Mo, Department of Electronic Engineering, Kun Shan University of Technology, Tainan, 710 Taiwan Chie-Tong Kuo, Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-sen University, Kaohsiung, 804 Taiwan Shuan-Yu Huang, School of Optometry, Chung Shan Medical University, Taichung, 402 Taiwan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A laser-plasma source comprising a rotating cryogenic solid-state Xe target has been studied for use in extreme ultraviolet lithography (EUVL) systems equipped with La/B 4 C mirrors. The laser-to-EUV power conversion efficiency (CE) of the cryogenic Xe target was improved to achieve a maximum CE of 0.15 % at 6.7 nm with 0.6 % bandwidth. We successfully demonstrated the continuous generation of EUV light with an average power of 80 mW at 6.7 nm with 0.6 % bandwidth using a Nd:YAG slab laser at a repetition rate of 320 Hz and an average power of 100 W. Scaling-up of the laser-plasma source for use as a future EUVL source is also discussed. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5215-2 Authors Sho Amano, Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Ako-gun, Hyogo 678-1205, Japan Tomoaki Inoue, Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Ako-gun, Hyogo 678-1205, Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The frequency upconversion (UC) emission throughout the visible region from the Y 2 O 3 :Ho 3+ –Tm 3+ –Yb 3+ co-doped phosphors synthesized by using low temperature combustion process upon excitation with a diode laser operating at 980 nm have been presented. The colour emission tunability in co-doped phosphor has been observed on increasing the pump power and seen by the naked eyes. The tunability in colour emission has also been visualized by CIE chromaticity diagram. The variation in UC emission intensity of the 1 G 4  →  3 H 6 (Tm 3+ ) and 5 F 3  →  5 I 8 (Ho 3+ ) transitions lying in the blue region has been monitored with increase in the pump power and marked that their ratio can be used to determine the temperature. The developed phosphor has been used to record fingerprints. The observed most intense visible colour emission from the developed material may be used for photodynamic therapy and as an alternative of traditional fluorescent biolabels. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5224-1 Authors Anurag Pandey, Laser and Spectroscopy Laboratory, Department of Applied Physics, Indian School of Mines, Dhanbad, 826004 Jharkhand, India Vineet Kumar Rai, Laser and Spectroscopy Laboratory, Department of Applied Physics, Indian School of Mines, Dhanbad, 826004 Jharkhand, India Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    In this paper, we discuss the interest of the singular value decomposition (SVD) data processing method applied to the in situ monitoring of gases (N 2 O) b mid-infrared quantum cascade laser absorption spectroscopy. An approach by simulation is used to determine the most appropriate parameters of the SVD treatment for this specific laser sensing application. The simulation is further used to estimate the effectiveness of the SVD in terms of improvement of the concentration data precision. Finally, the proposed SVD method is applied to experimental N 2 O measurements achieved in the laboratory with calibrated gas samples and with N 2 O flux measurements yielded during a field campaign in farm parcels. Content Type Journal Article Pages 1-11 DOI 10.1007/s00340-012-5205-4 Authors Irène Mappe-Fogaing, Groupe de Spectrométrie Moléculaire et Atmosphérique, Unité Mixte de Recherche Du Centre National de la Recherche Scientifique (UMR CNRS 6089), UFR Sciences Exactes et Naturelles, Université de Reims Champagne-Ardenne, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France Lilian Joly, Groupe de Spectrométrie Moléculaire et Atmosphérique, Unité Mixte de Recherche Du Centre National de la Recherche Scientifique (UMR CNRS 6089), UFR Sciences Exactes et Naturelles, Université de Reims Champagne-Ardenne, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France Georges Durry, Groupe de Spectrométrie Moléculaire et Atmosphérique, Unité Mixte de Recherche Du Centre National de la Recherche Scientifique (UMR CNRS 6089), UFR Sciences Exactes et Naturelles, Université de Reims Champagne-Ardenne, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France Nicolas Dumelié, Groupe de Spectrométrie Moléculaire et Atmosphérique, Unité Mixte de Recherche Du Centre National de la Recherche Scientifique (UMR CNRS 6089), UFR Sciences Exactes et Naturelles, Université de Reims Champagne-Ardenne, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France Thomas Decarpenterie, Groupe de Spectrométrie Moléculaire et Atmosphérique, Unité Mixte de Recherche Du Centre National de la Recherche Scientifique (UMR CNRS 6089), UFR Sciences Exactes et Naturelles, Université de Reims Champagne-Ardenne, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France Julien Cousin, Groupe de Spectrométrie Moléculaire et Atmosphérique, Unité Mixte de Recherche Du Centre National de la Recherche Scientifique (UMR CNRS 6089), UFR Sciences Exactes et Naturelles, Université de Reims Champagne-Ardenne, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A novel model of ultrafast interaction between THz pulse and carriers is built to study the THz-wave-induced quenching of femtosecond-laser-excited photoluminescence in CdTe and GaAs. Photoluminescence quenching is due to the nonequilibrium intervalley phonons induced by the THz field and subsequent decrease of the recombination efficiency of the electron–hole pairs. And the PLQ versus laser intensity experimental result agrees with the analysis. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-5191-6 Authors Zheng Chu, Wuhan National Laboratory for Optoelectronics, School of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China Jinsong Liu, Wuhan National Laboratory for Optoelectronics, School of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China Jingle Liu, Department of Physics, Applied Physics and Astronomy, Center for Terahertz Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    An experimental investigation of optical diffraction in three-dimensional self-assembled photonic crystals is herein presented. The crystals are synthesized using polystyrene colloidal particles of four different sphere diameters and diffraction is studied under three different wavelength illuminations. The differences in the relative intensities of diffracted spots indicate the twin face-centered cubic lattice arrangement of the crystals. This is confirmed by monitoring the variation in intensity of diffracted beam with respect to the incident angles. Moreover, the diffraction angle versus the incidence angle plot provides us with an estimate of the colloidal sphere diameter. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5144-0 Authors Sunita Kedia, Theoretical Physics Division, Physical Research Laboratory, Navrangpura, Ahmedabad, 380 009 India Ashok Kumar, Theoretical Physics Division, Physical Research Laboratory, Navrangpura, Ahmedabad, 380 009 India R. P. Singh, Theoretical Physics Division, Physical Research Laboratory, Navrangpura, Ahmedabad, 380 009 India Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    This paper discusses the relationships among the aerosol extinction coefficient error (AECE), background noise, and distance associated with lidar measurements. The AECE calculation is explained in detail, revealing that the AECE is the product of background noise, range squared, and a relation function. The result of an AECE calculation that uses lidar measurements obtained in Nanjing, China, agrees with a calculation that uses a simulated lidar signal. The AECE equation is verified with lidar measurement data and a simulated lidar signal, indicating the AECE equation is reasonable. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5204-5 Authors Nianwen Cao, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, 210044 China Jianzhong Shi, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, 210044 China Fengkai Yang, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, 210044 China Peng Yan, Center for Atmosphere Watch and Services, CMA, Beijing, 100081 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We calculate the field distribution based on the vector diffraction theory for a superposition of spirally phase shifted radially polarized beams. Twisted longitudinally polarized field is found in the focal region. The total intensity as well as the polarization components rotates around the beam axis near the focus. Calculation of the Poynting vector at the focal plane shows that the electromagnetic energy is redistributed between different polarization components. Nonzero value of transverse components of the Poynting vector implies the transverse flow of the energy in the focal region. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5239-7 Authors Sunil Vyas, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-8577 Japan Yuichi Kozawa, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-8577 Japan Shunichi Sato, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-8577 Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The paper reports the study of thermal decomposition of 3(5)-nitropyrozole, 4-nitropyrazole and 1-nitropyrazole using time-resolved pulsed photoacoustic spectroscopy technique for the first time. The second harmonic, i.e., λ  = 532 nm, 7 ns pulse width at 10 Hz repetition rate, obtained from Q-switched Nd: YAG laser has been employed. In addition, we have studied the effect of pressure, temperature and incident laser energy on the thermal decomposition mechanism of nitropyrazoles. The strength of photoacoustic signal provides significant information about the multistep thermal decomposition mechanism of 3(5)-nitropyrazole and 4-nitropyrazole, while 1-nitropyrazole follows the path of direct decomposition based on single reaction, which is also verified by the thermal gravimetric–differential thermal analysis (TG–DTA) technique. We have also experimentally demonstrated the presence of free NO 2 before the melting point, which is due to the thermal dissociation of solid nitropyrazole compounds. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5240-1 Authors F. Yehya, Advanced Centre of Research in High Energy Materials, University of Hyderabad, Hyderabad, 500 046 India A. K. Chaudhary, Advanced Centre of Research in High Energy Materials, University of Hyderabad, Hyderabad, 500 046 India Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We demonstrate experimentally that the resolution of amplitude noise spectrum in Cs atomic vapor can be enhanced by narrowing the absorption using velocity selective optical pumping technique. It is found that the steep atomic dispersion accompanied by high absorption leads to more conversion of laser phase noise to amplitude noise, when the field propagates throughout the atoms, and meanwhile the spectral resolution is improved. The effect of optical pumping intensity on the spectrum resolution is experimentally discussed, and a theoretical explanation for this phenomenon is given, which shows that the phase-to-amplitude noise conversion is directly proportional to the dispersion of medium. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5211-6 Authors Yuan Li, The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, 030006 China Dehuan Cai, The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, 030006 China Rong Ma, The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, 030006 China Dan Wang, The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, 030006 China Jiangrui Gao, The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, 030006 China Junxiang Zhang, The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, 030006 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A novel, fiber-optic in situ laser hygrometer was developed to measure water vapor with microsecond time resolution directly inside an internal combustion (IC) engine. The instrument is intended for sampling-free quantification of recirculated exhaust gas in combustion engines. Direct tunable diode laser absorption spectroscopy was employed to allow absolute and self-calibrating H 2 O measurements. The compact and user-friendly instrument combines a fiber-coupled, 1.37 μm distributed feedback diode laser with kHz-fast, continuous wavelength scanning. Only small, typically 10 mm, optical access ports in the engine are needed. The new in situ hygrometer was tested via measurements in a motored optical research engine operated on ambient air, without any artificial humidification. Scanning the laser at 4 kHz resulted in a time resolution of 250 μs (i.e., 3° crank angle at 2,000 rpm), while the DC-coupled detector signals are digitized with a 4MSamples/s 16-bit data acquisition system. Absolute water vapor concentrations around 1 vol.% could be measured and quantified during the full compression stroke, i.e., over a pressure/temperature range of 0.07–0.52 MPa/300–500 K. Without any scan averaging or bandwidth filtering we could demonstrate signal-to-noise ratios between 51 (at p  = 0.1 MPa) and 33 (at p  = 0.4 MPa), which corresponds to H 2 O detection limits between 0.02 and 0.035 vol.% or length and bandwidth normalized detectivities of 285 and 477 ppb m Hz −½ , respectively. Comparison of the dynamic H 2 O behavior during the compression stroke across several engine cycles and different operating conditions showed good reproducibility and absolute accuracy of the results, consistent with the boundary conditions, i.e., motored air operation. This new sensor therefore opens up new possibilities for engine cycle-resolved, calibration-free in situ AGR quantification and optimization in engine applications. Content Type Journal Article Pages 1-12 DOI 10.1007/s00340-012-5225-0 Authors O. Witzel, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany A. Klein, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany S. Wagner, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany C. Meffert, IVG, Institute for Combustion and Gasdynamics, University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany C. Schulz, IVG, Institute for Combustion and Gasdynamics, University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany V. Ebert, Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We found that tetragonal Gd 0.5 Lu 0.5 VO 4 —known as host-crystal for Ln 3+ -lasants—is an attractive optical material for Raman laser converters. We discovered and investigated its almost sesqui-octave Stokes and anti-Stokes lasing comb resulting from four SRS-promoting vibration modes in combination with cascaded and cross-cascaded many-phonon χ (3) -nonlinear interactions. Furthermore, estimations of the steady-state Raman gain coefficient have been performed. Content Type Journal Article Pages 1-10 DOI 10.1007/s00340-012-5233-0 Authors A. A. Kaminskii, Institute of Crystallography, Russian Academy of Sciences, Moscow, 119333 Russia O. Lux, Institute of Optics and Atomic Physics, TU Berlin, 10623 Berlin, Germany H. Rhee, Institute of Optics and Atomic Physics, TU Berlin, 10623 Berlin, Germany H. J. Eichler, Institute of Optics and Atomic Physics, TU Berlin, 10623 Berlin, Germany H. Yoneda, Institute for Laser Science, University of Electro-Communications, Tokyo, 182-8585 Japan A. Shirakawa, Institute for Laser Science, University of Electro-Communications, Tokyo, 182-8585 Japan K. Ueda, Institute for Laser Science, University of Electro-Communications, Tokyo, 182-8585 Japan B. Zhao, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, 350108 China J. Chen, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, 350108 China J. Dong, Department of Electronic Engineering, School of Information and Technology of Xiamen University, Xiamen, 361005 China J. Zhang, Jiangsu Normal University, Xuzhou, 221116 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We have developed a diode-pumped passively mode-locked Nd 3+ :CLTGG laser operated at 1059 and 1061 nm with a semiconductor saturable absorber mirror (SESAM). The relative intensity of the two spectrum wavelengths is adjustable, allowing asynchronous and synchronous generation of the dual-wavelength pulses. In synchronous mode-locking regime, a total average output power of 383 mW was obtained with pulse duration of 3.5 ps and repetition rate of 42 MHz. The two spectral bands of 1059 and 1061 nm had the same intensities and areas, indicating 1:1 for the pulse energy ratio. It is desirable for efficiently generating a terahertz wave by difference-frequency generation. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-4877-0 Authors J.-L. Xu, State Key Laboratory of Crystal Materials, Shandong University, Ji’nan, 250100 China S.-Y. Guo, State Key Laboratory of Crystal Materials, Shandong University, Ji’nan, 250100 China J.-L. He, State Key Laboratory of Crystal Materials, Shandong University, Ji’nan, 250100 China B.-Y. Zhang, State Key Laboratory of Crystal Materials, Shandong University, Ji’nan, 250100 China Y. Yang, State Key Laboratory of Crystal Materials, Shandong University, Ji’nan, 250100 China H. Yang, State Key Laboratory of Crystal Materials, Shandong University, Ji’nan, 250100 China S.-D. Liu, State Key Laboratory of Crystal Materials, Shandong University, Ji’nan, 250100 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Based on a new spectrophone configuration using a single microresonator (mR) in “on beam” quartz-enhanced photoacoustic spectroscopy (QEPAS), referred to “half on beam QEPAS”, a classical acoustic model originated from “orifice ended tube” was introduced to model and optimize the mR geometrical parameters. The calculated optimum mR parameters were in good agreement with the experimental results obtained in “half on beam” as well as conventional “on beam” QEPAS approaches through monitoring of atmospheric H 2 O vapor absorption. In addition, spectrophone performances of different QEPAS configurations (off beam, on beam and half on beam) were compared in terms of signal-to-noise ratio (SNR) gain. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-4988-7 Authors H. Yi, Key Laboratory of Atmospheric Composition and Optical Radiation, Chinese Academy of Science, Hefei, 230031 China W. Chen, Laboratoire de Physicochimie del’Atmosphère, Université du Littoral Côte d’Opale, 189A, Av. Maurice Schumann, 59140 Dunkerque, France X. Guo, Space Information and Simulation Technology Lab, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing, 100190 China S. Sun, Key Laboratory of Atmospheric Composition and Optical Radiation, Chinese Academy of Science, Hefei, 230031 China K. Liu, Key Laboratory of Atmospheric Composition and Optical Radiation, Chinese Academy of Science, Hefei, 230031 China T. Tan, Key Laboratory of Atmospheric Composition and Optical Radiation, Chinese Academy of Science, Hefei, 230031 China W. Zhang, Key Laboratory of Atmospheric Composition and Optical Radiation, Chinese Academy of Science, Hefei, 230031 China X. Gao, Key Laboratory of Atmospheric Composition and Optical Radiation, Chinese Academy of Science, Hefei, 230031 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Glasses with the composition 30PbO–25Sb 2 O 3 –(45− x )B 2 O 3 – x Dy 2 O 3 for x =0 to 1 were prepared in steps of 0.2 by the melt-quenching method. Various physical parameters, viz., density, molar volume, and oxygen packing density, were evaluated. Optical absorption and luminescence spectra of all the glasses were recorded at room temperature. From the observed absorption edges optical band gap, the Urbach energies are calculated; the optical band gap is found to decrease with the concentration of Dy 2 O 3 . The Judd–Ofelt theory was applied to characterize the absorption and luminescence spectra of Dy 3+ ions in these glasses. Following the luminescence spectra, various radiative properties, like transition probability A , branching ratio β and the radiative life time τ for different emission levels of Dy 3+ ions, have been evaluated. The radiative lifetime for the 4 F 9/2 multiplet has also been evaluated from the recorded life time decay curves, and the quantum efficiencies were estimated for all the glasses. The quantum efficiency is found to increase with the concentration of Dy 2 O 3 . Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-4983-z Authors M. Chandra Shekhar Reddy, Department of Physics, PRRM Engineering College, Shabad, Hyderabad, 509 217 India B. Appa Rao, Department of Physics, Osmania University, Hyderabad, 500 007 India M. G. Brik, Institute of Physics, University of Tartu, Riia 142, Tartu, 51014 Estonia A. Prabhakar Reddy, Department of Physics, Osmania University, Hyderabad, 500 007 India P. Raghava Rao, Dept. Physics, Acharya Nagarjuna University, Nuzvid Campus, Nuzvid, 521201 A.P., India C. K. Jayasankar, Department of Physics, S.V. University, Thirupathi, 517 502 India N. Veeraiah, Dept. Physics, Acharya Nagarjuna University, Nuzvid Campus, Nuzvid, 521201 A.P., India Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Gd 2 O 3 :Eu 3+ (4 mol%) co-doped with Bi 3+ (Bi = 0, 1, 3, 5, 7, 9 and 11 mol%) ions were synthesized by a low-temperature solution combustion method. The powders were calcined at 800°C and were characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), Fourier transform infrared and UV–Vis spectroscopy. The PXRD profiles confirm that the calcined products were in monoclinic with little cubic phases. The particle sizes were estimated using Scherrer’s method and Williamson–Hall plots and are found to be in the ranges 40–60 nm and 30–80 nm, respectively. The results are in good agreement with TEM results. The photoluminescence spectra of the synthesized phosphors excited with 230 nm show emission peaks at ∼590, 612 and 625 nm, which are due to the transitions 5 D 0 → 7 F 0 , 5 D 0 → 7 F 2 and 5 D 0 → 7 F 3 of Eu 3+ , respectively. It is observed that a significant quenching of Eu 3+ emission was observed under 230 nm excitation when Bi 3+ was co-doped. On the other hand, upon 350 nm excitation, the luminescent intensity of Eu 3+ ions was enhanced by incorporation of Bi 3+ (5 mol%) ions. The introduction of Bi 3+ ions broadened the excitation band of Eu 3+ of which a new strong band occurred ranging from 320 to 380 nm. This has been attributed to the 6s 2 →6s6p transition of Bi 3+ ions, implying a very efficient energy transfer from Bi 3+ ions to Eu 3+ ions. The gamma radiation response of Gd 2 O 3 :Eu 3+ exhibited a dosimetrically useful glow peak at 380°C. Using thermoluminescence glow peaks, the trap parameters have been evaluated and discussed. The observed emission characteristics and energy transfer indicate that Gd 2 O 3 :Eu 3+ , Bi 3+ phosphors have promising applications in solid-state lighting. Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-012-4927-7 Authors N. Dhananjaya, Department of Physics, J.B. Campus, Bangalore University, Bangalore, 560 056 India H. Nagabhushana, Prof. C.N.R. Rao Centre for Nano Research (CNR), Tumkur University, Tumkur, 572 103 India B. M. Nagabhushana, Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore, 560 054 India S. C. Sharma, Prof. C.N.R. Rao Centre for Nano Research (CNR), Tumkur University, Tumkur, 572 103 India B. Rudraswamy, Department of Physics, J.B. Campus, Bangalore University, Bangalore, 560 056 India N. Suriyamurthy, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakam, 603 102 India C. Shivakumara, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, 560 012 India R. P. S. Chakradhar, National Aerospace Laboratories (CSIR), Bangalore, 560 017 India Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    n -ZnO:Al/ n − -ZnO/ i -MgO/ n -GaN heterostructured diodes have been fabricated by radio frequency magnetron sputtering. The electroluminescence (EL) of the n -ZnO:Al/ n − -ZnO/ i -MgO/ n -GaN diodes has been investigated. All EL spectra are dominated by ultraviolet (UV) emission peaked at around 368 nm. However, EL performances of the devices can be tuned through controlling the electrical parameters of ZnO:Al films. With the variation of the ZnO:Al films, EL spectra could evolve into random lasing action from conventional EL. The electrical parameters of the corresponding ZnO:Al films were researched, and the related UV emission mechanism is discussed in terms of the energy-band theory of the heterojunctions. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-4966-0 Authors S. Li, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, P.R. China G. Fang, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, P.R. China H. Huang, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, P.R. China H. Long, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, P.R. China H. Wang, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, P.R. China X. Mo, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, P.R. China B. Dong, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, P.R. China X. Zhao, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology, Wuhan University, Wuhan, Hubei 430072, P.R. China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We report the development of a laser sonde operated under stratospheric balloons and devoted to the in-situ measurement of carbon dioxide in the upper troposphere and the lower stratosphere. In the 2.68 micron region, strong CO 2 transitions are suitable for the in-situ monitoring of carbon dioxide, which gives ∼10% absorption depth and, moreover, antimonide laser diodes are nowadays available that show relevant spectral properties for absorption spectroscopy. The light-weight sensor is based on 50-cm single path configuration and is operated open to the atmosphere. We provide details of the design of the instrument and data processing. The performance and the stability of the instrument were evaluated with the Allan variance technique. The spectrometer was test-flown in the Arctic stratosphere from Kiruna, Sweden and we report preliminary flight results. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-4887-y Authors M. Ghysels, Groupe de Spectrométrie moléculaire et Atmosphérique, UMR CNRS 6089, Université de Reims, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France G. Durry, Groupe de Spectrométrie moléculaire et Atmosphérique, UMR CNRS 6089, Université de Reims, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France N. Amarouche, Division technique de l’Institut National des Sciences de l’Univers, UPS CNRS 855, 92195 Meudon Cédex, France J. Cousin, Groupe de Spectrométrie moléculaire et Atmosphérique, UMR CNRS 6089, Université de Reims, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France L. Joly, Groupe de Spectrométrie moléculaire et Atmosphérique, UMR CNRS 6089, Université de Reims, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France E. D. Riviere, Groupe de Spectrométrie moléculaire et Atmosphérique, UMR CNRS 6089, Université de Reims, Moulin de la Housse, BP 1039, 51687 Reims Cedex 2, France L. Beaumont, Division technique de l’Institut National des Sciences de l’Univers, UPS CNRS 855, 92195 Meudon Cédex, France Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    An adjustable chromaticity layer was successfully applied to a TBADN-based blue organic light-emitting device (BOLED) for improving chromaticity and luminance efficiency. The device was constructed by sandwiching an ultrathin [DPVBi: BCzVB] layer between hole-transport layer and primary emission layer. The optimized device gives the Commission Internationale de I’éclairage (CIE) color coordinates of (0.166, 0.201) at the current density of 20 mA/cm 2 and a maximum luminance efficiency of 8.43 cd/A at the driving voltage of 11 V. Content Type Journal Article Pages 1-4 DOI 10.1007/s00340-012-4967-z Authors H.-P. Lin, Department of Materials Science, Shanghai University, Jiading, Shanghai, 201800 People’s Republic of China F. Zhou, Department of Materials Science, Shanghai University, Jiading, Shanghai, 201800 People’s Republic of China J. Li, Department of Materials Science, Shanghai University, Jiading, Shanghai, 201800 People’s Republic of China X.-W. Zhang, Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin, 541004 People’s Republic of China X.-Y. Jiang, Department of Materials Science, Shanghai University, Jiading, Shanghai, 201800 People’s Republic of China Z.-L. Zhang, Department of Materials Science, Shanghai University, Jiading, Shanghai, 201800 People’s Republic of China J.-H. Zhang, Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University, Shanghai, 200072 People’s Republic of China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We present continuously tunable Vertical External Cavity Surface Emitting Lasers (VECSEL) in the mid-infrared. The structure based on IV–VI semiconductors is epitaxially grown on a Si-substrates. The VECSEL emit one single mode, which is mode hop-free tunable over 50–100 nm around the center wavelength. In this work, two different devices are presented, emitting at 3.4 μm and 3.9 μm, respectively. The lasers operate near room temperature with thermoelectric stabilization. They are optically pumped, yielding an output power 〉10 mW p . The axial symmetric emission beam has a half divergence angle of 〈3.3 ∘ . Content Type Journal Article Pages 1-4 DOI 10.1007/s00340-012-5096-4 Authors M. Fill, ETH Zürich, Technoparkstr. 1, 8005 Zurich, Switzerland F. Felder, ETH Zürich, Technoparkstr. 1, 8005 Zurich, Switzerland M. Rahim, ETH Zürich, Technoparkstr. 1, 8005 Zurich, Switzerland A. Khiar, ETH Zürich, Technoparkstr. 1, 8005 Zurich, Switzerland H. Zogg, ETH Zürich, Technoparkstr. 1, 8005 Zurich, Switzerland Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We demonstrate simultaneous type-0 and type-II spontaneous parametric down-conversions (SPDCs) in a single periodically poled KTiOPO 4 (KTP) crystal with a domain-inversion period of 10.00 μm. When a 45° linearly polarized 405 nm pump laser was injected into the crystal, the type-0 and the type-II SPDCs were simultaneously obtained using the third-order quasiphase matching (QPM) with the d 33 and the first-order QPM with the d 24 of KTP, respectively. We observed ring images due to the noncollinear propagation of the signals satisfying the three-dimensional type-0 and type-II QPM conditions, respectively. The observed results were in agreement with the calculated results based on the Sellmeier’s formulas. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5088-4 Authors H. J. Lee, Department of Physics, Pusan National University, Busan, 609-735 Korea H. Kim, Basic Science Research Institute, University of Ulsan, Ulsan, 680-749 Korea M. Cha, Department of Physics, Pusan National University, Busan, 609-735 Korea H. S. Moon, Department of Physics, Pusan National University, Busan, 609-735 Korea Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We report Tunable Diode Laser Spectroscopy measurements of propane using a recently developed 3.37 μm GaInAsSb/AlGaInAsSb DFB laser. We have demonstrated that Wavelength Modulation Spectroscopy can be utilized to enhance a sharp feature in the broader propane spectrum around 3370.4 nm. A minimum detectable concentration of 30 ppb×m was obtained at a response time of 0.5 s. This corresponded to a minimum detectable absorption of 8 × 10 −5 which is why an improvement of the sensitivity by an order of magnitude is possible using this laser and a more optimized optical setup. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5054-1 Authors P. Kluczynski, Airoptic Sp. z.o.o., ul. J. Omańkowskiej 58, 60-465 Poznań, Poland S. Lundqvist, Siemens AB, IIA SLA R&D, Box 14153, 400 20 Göteborg, Sweden S. Belahsene, Institut d’Electronique du Sud, Université Montpellier 2, 34095 Montpellier, France Y. Rouillard, Institut d’Electronique du Sud, Université Montpellier 2, 34095 Montpellier, France L. Nähle, Nanoplus GmbH, Oberer Kirschberg 4, 97218 Gerbrunn, Germany M. Fischer, Nanoplus GmbH, Oberer Kirschberg 4, 97218 Gerbrunn, Germany J. Koeth, Nanoplus GmbH, Oberer Kirschberg 4, 97218 Gerbrunn, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    In this work, supercontinuum conical emission (SC CE) accompanying the filamentation of powerful ultrashort laser pulse in BK 7 glass and fused silica is studied. The SC CE is controlled by the laser power density and the sample thickness, and the minimum SC CE cut-off wavelength is about 309 nm in the BK 7 glass and 237 nm in the fused silica. The angular distributions of the SC CE in the wavelength range less than 510 nm are measured by using a new method, and it cannot be explained by the Cerenkov emission theory but the unabridged X-Waves solution theory. Meanwhile numerical simulations of the propagation of femtosecond laser pulse in sample are performed to provide theoretical support to our results. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5079-5 Authors Z. Liu, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000 P.R. China X. Lu, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000 P.R. China Q. Liu, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000 P.R. China S. Sun, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000 P.R. China L. Li, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000 P.R. China X. Liu, 91991 PLA troops, Zhoushan, 316000 P.R. China B. Ding, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000 P.R. China B. Hu, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000 P.R. China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Catalytic oxidation reaction monitoring has been performed for the first time with a trace gas carbon dioxide analyser based on a continuous wave (cw), thermoelectrically cooled (TEC), distributed feedback (DFB) quantum cascade laser (QCL) operating at around 2307 cm −1 . The reaction kinetics for carbon monoxide oxidation over a platinum catalyst supported on yttria-stabilised zirconia were followed by the QCL CO 2 analyser and showed that it is a powerful new tool for measuring low reaction rates associated with low surface area model catalysts operating at atmospheric pressures. A detection limit was determined of 40 ppb (1 standard deviation) for a 0.1 s average and a residual absorption standard deviation of 1.9×10 −4 . Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-5154-y Authors V. L. Kasyutich, School of Chemical Engineering and Analytical Science, University of Manchester, Oxford Road, Manchester, M13 9PL UK D. Poulidi, School of Chemical Engineering and Advanced Materials, Metz Court, Newcastle University, Newcastle upon Tyne, NE1 7RU UK M. Jalil, School of Chemical Engineering and Advanced Materials, Metz Court, Newcastle University, Newcastle upon Tyne, NE1 7RU UK I. S. Metcalfe, School of Chemical Engineering and Advanced Materials, Metz Court, Newcastle University, Newcastle upon Tyne, NE1 7RU UK P. A. Martin, School of Chemical Engineering and Analytical Science, University of Manchester, Oxford Road, Manchester, M13 9PL UK Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The characteristics of a novel Discrete Mode laser diode are described with particular reference to its capability in spectroscopic based gas sensing. In this regard, its emission linewidth, Side Mode Suppression Ratio and tuneability are of particular note. The measured narrow linewidth of 550 kHz has applications with respect to spectrally narrow absorption features found, for example, in saturated absorption lines, in hyperfine structure of some rotational manifolds and in whispering gallery mode features associated with optical microspheres. Other notable measured characteristics show mode-hop-free temperature tuning of 11 nm at a linear tuning rate of 0.1 nm/°C and a Side Mode Suppression Ratio in the range 56 to 46 dB and a long term (72 hours) wavelength stability of 1 pm per day. In essence, this novel Discrete Mode laser displays excellent potential for diode laser based sensing applications in the near infrared. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5167-6 Authors V. Weldon, Semiconductor Photonics Group, School of Physics, Trinity College Dublin, Dublin, Ireland P. Pineda-Vadillo, Semiconductor Photonics Group, School of Physics, Trinity College Dublin, Dublin, Ireland M. Lynch, Semiconductor Photonics Group, School of Physics, Trinity College Dublin, Dublin, Ireland R. Phelan, Eblana Photonics, Trinity Technology and Enterprise Campus, Pearse St., Dublin, 2 Ireland J. F. Donegan, Semiconductor Photonics Group, School of Physics, Trinity College Dublin, Dublin, Ireland Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Temperature dependence of threshold and gain coefficient of stimulated Brillouin scattering (SBS) was investigated. It was found that the threshold of SBS decreases with the increase of temperature. Based on the definition of the threshold, a new method was proposed for determining the gain coefficient of SBS of the material experimentally by measuring the threshold. It reveals that the threshold and the gain coefficient of SBS of a material are strongly related to temperature. Content Type Journal Article Category Rapid Communication Pages 1-4 DOI 10.1007/s00340-012-5142-2 Authors Jiulin Shi, Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China Yijun Tang, Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nachang, 330063 China Hongjun Wei, Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nachang, 330063 China Lei Zhang, Applied Optics Beijing Area Major Laboratory, Department of Physics, Beijing Normal University, Beijing, 100875 China Dong Zhang, Applied Optics Beijing Area Major Laboratory, Department of Physics, Beijing Normal University, Beijing, 100875 China Jinwei Shi, Applied Optics Beijing Area Major Laboratory, Department of Physics, Beijing Normal University, Beijing, 100875 China Wenping Gong, Applied Optics Beijing Area Major Laboratory, Department of Physics, Beijing Normal University, Beijing, 100875 China Xingdao He, Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nachang, 330063 China Kecheng Yang, Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China Dahe Liu, Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hangkong University, Nachang, 330063 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    This study presents a 2.06 μm single-frequency tunable volume Bragg grating (VBG)-based short-cavity Tm:Ho:YLF laser. A mode-hop-free tuning range of 10 GHz at a few hundred mW output power was achieved. The first-derivative spectrum of the CO 2 20013←00001 R(4) absorption line with a signal-to-noise ratio (SNR) of 1,000/Hz 1/2 was obtained using frequency modulation and fluorescence detection. The laser frequency can be stabilized to the CO 2 line with a stability of 3 × 10 −9 . Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5159-6 Authors Pei-Ling Luo, Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, 30013 Taiwan Chien-Cheng Kuo, Graduate Institute of Energy Engineering, National Central University, Chung-Li, 32001 Taiwan Cheng-Chung Lee, Department of Optics and Photonics, National Central University, Chung-Li, 32001 Taiwan Jow-Tsong Shy, Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, 30013 Taiwan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Based on the easily controllable radio frequency magnetron sputtering, n -ZnO and i -MgO thin films were fabricated on p + -GaN substrate to construct heterojunctional light-emitting diodes for ultraviolet emission from the near band edge exciton recombination of ZnO. Effects of the insulator MgO layer on the electroluminescent performance of the n -ZnO/ i -MgO/p + -GaN light-emitting diodes have been investigated. It was found that the light-emitting diode presented stronger near band-edge emission with blue shift emission peak under the lower working current when i -MgO layer was inserted. The fabrication process, characteristics and the mechanism were discussed in detail. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5161-z Authors G. Y. Zhu, State Key Laboratory of Bioelectronics, and Advanced Photonics Center, School of Biological Science and Medical Engineering, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 People’s Republic of China J. T. Li, State Key Laboratory of Bioelectronics, and Advanced Photonics Center, School of Biological Science and Medical Engineering, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 People’s Republic of China Z. L. Shi, State Key Laboratory of Bioelectronics, and Advanced Photonics Center, School of Biological Science and Medical Engineering, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 People’s Republic of China Y. Lin, State Key Laboratory of Bioelectronics, and Advanced Photonics Center, School of Biological Science and Medical Engineering, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 People’s Republic of China G. F. Chen, State Key Laboratory of Bioelectronics, and Advanced Photonics Center, School of Biological Science and Medical Engineering, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 People’s Republic of China T. Ding, State Key Laboratory of Bioelectronics, and Advanced Photonics Center, School of Biological Science and Medical Engineering, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 People’s Republic of China Z. S. Tian, State Key Laboratory of Bioelectronics, and Advanced Photonics Center, School of Biological Science and Medical Engineering, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 People’s Republic of China C. X. Xu, State Key Laboratory of Bioelectronics, and Advanced Photonics Center, School of Biological Science and Medical Engineering, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096 People’s Republic of China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The defect mode in silver-doped photonic crystals is investigated. 1D and 3D photonic crystals were made by holography using dichromated gelatin mixed with silver nitrate. By controlling the concentration of the silver nitrate, the defect mode was observed in the bandgaps of the holographic photonic crystals. The numerical simulations were made, and the results showed the consistency with the experimental observations. Content Type Journal Article Pages 1-4 DOI 10.1007/s00340-012-5148-9 Authors Rui Dai, School of Physics, Northeast Normal University, Changchun, 130024 China Shujing Chen, Department of Physics, Applied Optics, Beijing Area Major Laboratory, Beijing Normal University, Beijing, 100875 China Zhi Ren, School of Mathematics and Physics, North China Electric Power University, Baoding, 071003 China Zhaona Wang, Department of Physics, Applied Optics, Beijing Area Major Laboratory, Beijing Normal University, Beijing, 100875 China Dahe Liu, Department of Physics, Applied Optics, Beijing Area Major Laboratory, Beijing Normal University, Beijing, 100875 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We demonstrate compensation for the spherical aberration due to the refractive index mismatch that occurs when a laser beam is focused into a thick arsenic trisulfide (As 2 S 3 ) film with a high numerical aperture objective. The effects of the aberration at different focal depths on the point spread function have been calculated numerically and the axial response method shown to be a useful measure for compensating the spherical aberration. We show that with the addition of adaptive optics based on a spatial light modulator, the aberration can be significantly reduced, resulting in an increase in peak intensity by a factor of 2.4 and a decrease in axial elongation by a factor of 2.2. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5180-9 Authors Benjamin P. Cumming, Centre for Micro-Photonics, Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, VIC 3122, Australia Sukanta Debbarma, Laser Physics Centre, Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia Barry Luther-Davies, Laser Physics Centre, Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia Min Gu, Centre for Micro-Photonics, Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, VIC 3122, Australia Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Ultrashort 198- and 158-nm pulses are generated simultaneously by cascaded four-wave mixing of the second and third harmonics of a 80-fs Ti:Sapphire laser in filamentation propagation through a single Ar gas cell. The energies of the 198- and 158-nm pulses are 7.6 μJ and 600 nJ, respectively. The duration of 198-nm pulse is determined to be ca. 45 fs by transient-grating frequency-resolved optical grating, which indicates that the pulse is intrinsically transform limited and chirped by the rear window of the gas cell. The spectral bandwidths of 198- and 158 nm support the transform limited pulse durations of 40 and 28 fs, respectively. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5146-y Authors Peng Zuo, Advanced Science Institute, RIKEN, Wako, Saitama 351-0198, Japan Takao Fuji, Advanced Science Institute, RIKEN, Wako, Saitama 351-0198, Japan Takuya Horio, Japan Science and Technology Agency, CREST, Tokyo, 102-0075 Japan Shunsuke Adachi, Japan Science and Technology Agency, CREST, Tokyo, 102-0075 Japan Toshinori Suzuki, Advanced Science Institute, RIKEN, Wako, Saitama 351-0198, Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    This study designs and characterizes a novel precise optics-based autofocusing microscope with both the large linear autofocusing range and the rapid response. In contrast to conventional optics-based autofocusing microscopes with centroid method, the proposed microscope comprises two optical paths, namely one optical path which provides a short linear autofocusing range but an extremely high focusing accuracy and a second optical path which achieves a long linear autofocusing range but a reduced focusing accuracy. The two optical paths are combined using a self-written autofocus-processing algorithm to realize an autofocusing microscope with a large linear autofocusing range, a rapid response, and a high focusing accuracy. The microscope is characterized numerically using commercial software ZEMAX and is then verified experimentally using a laboratory-built prototype. The experimental results show that compared to conventional optics-based autofocusing microscopes with centroid method and a single optical path, the proposed microscope achieves both a longer autofocusing range and a more rapid response with no reduction in the focusing accuracy. Overall, the results presented in this study show that the proposed microscope provides an ideal solution for automatic optical inspection and industrial applications. Content Type Journal Article Pages 1-10 DOI 10.1007/s00340-012-5171-x Authors Chien-Sheng Liu, Department of Mechanical Engineering, National Chung Cheng University, No.168, University Road, Minhsiung Township, Chiayi, 62102 Taiwan Pin-Hao Hu, Laser Application Technology Center Industrial Technology Research Institute, R208, No. 8, Gongyan Rd., Liujia Shiang, Tainan, 734 Taiwan Yang-Cheng Lin, Laser Application Technology Center Industrial Technology Research Institute, R208, No. 8, Gongyan Rd., Liujia Shiang, Tainan, 734 Taiwan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We developed a low-power, portable, wireless laser spectroscopic sensor for atmospheric CO 2 monitoring. The sensor is based on tunable diode laser absorption spectroscopy with a 2-μm wavelength VCSEL as a source and wavelength modulation technique for spectroscopic signal detection. The sensor allows measurement of CO 2 concentration changes with a 1 σ sensitivity of 0.14 ppmv Hz −1/2 . This sensor was both laboratory and field tested under varying environmental conditions. It was used to measure a soil respiration rate of topsoil in the lab and of forest floors in the field. Measurement results are compared with those of commercial non-dispersive infrared sensors and very good agreement is found. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5157-8 Authors C. J. Smith, Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA S. So, Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA L. Xia, Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, MD 21218, USA S. Pitz, Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, MD 21218, USA K. Szlavecz, Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, MD 21218, USA D. Carlson, Department of Computer Science, The Johns Hopkins University, Baltimore, MD 21218, USA A. Terzis, Department of Computer Science, The Johns Hopkins University, Baltimore, MD 21218, USA G. Wysocki, Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We report one- and two-dimensional arbitrary patterns which are achieved by nanocavity waveguides made of a quasi-metal–dielectric-metal heterostructure with omnidirectional illumination. This proposed heterostructure supports the surface plasmon polaritons whose phase and group velocities have opposite sign for given frequency. Negative refraction and reflection in the waveguide result in imaging nanolithography and the omnidirectional property can be well understood by the dispersive relation of the nanocavity waveguide. Numerical results demonstrate that such an omnidirectional nanolithography scheme is feasible for arbitrary 1D gratings and 2D linearly chirped gratings with TM and circular polarized incidence, respectively, at 365 nm. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5197-0 Authors Xuefeng Yang, School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798 Singapore Dao Hua Zhang, School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798 Singapore Zhengji Xu, School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798 Singapore Yueke Wang, School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798 Singapore Jun Wang, School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798 Singapore Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We demonstrated that molecular-alignment-based cross-correlation frequency resolved optical gating (M-XFROG) could be used for complete characterization of elliptically polarized femtosecond pulses by measuring the orthogonal linear polarization components and the additional polarization projection at 45 degree of the target pulse. The electric field orientation, polarization ellipticity angles, and phase information of the target pulse were also obtained. The transiently aligned air molecules functioned as a linear optical gating function in the measurement processes. The validity and robustness of M-XFROG were confirmed by the comparison between the retrieved optical gating function and measured molecular alignment signal in air. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5132-4 Authors Hao Li, State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062 China Wenxue Li, State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062 China Jia Liu, State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062 China Haifeng Pan, State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062 China Jian Wu, State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062 China Heping Zeng, State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We present measurements of the Gouy phase accumulation for the fundamental mode of an astigmatic Fabry–Perot cavity over 70 % of its stability range. The method is based on simultaneous measurement of the resonant frequencies of the fundamental mode and the \text TEM 11 Hermite–Gauss mode of the cavity. We achieve an uncertainty of 2.7×10 - 6  rad, which, in the context of displacement metrology, is sufficient to enable measurements over 50 mm with relative uncertainty below 10 - 10 . Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5147-x Authors Mathieu Durand, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA Yicheng Wang, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA John Lawall, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We employed a 9-mm long periodically poled KTiOPO 4 (PPKTP) crystal in an optical parametric oscillator (OPO) to generate sub-nanosecond idler pulses around 2.8 μm. With a 1-cm long OPO cavity in a singly resonant configuration and double pass pumping by 1-ns pulses at 1,064 nm, the maximum idler energy reached 110 μJ at 1 kHz. Pumping with 500 ps pulses at 1–10 kHz, resulted in an idler energy of ~50 μJ and the shortest pulse duration of ~250 ps, ever reported for an OPO. The corresponding quantum conversion efficiencies were 32.5 and 34.9 %, respectively. Content Type Journal Article Pages 1-4 DOI 10.1007/s00340-012-5177-4 Authors Georgi Marchev, Max-Born-Institute for Nonlinear Optics and Ultrafast Spectroscopy, 2A, Max-Born-Str, 12489 Berlin, Germany Paolo Dallocchio, INFN and Dipartimento di Elettronica dell’Università di Pavia, Via Ferrata 1, 27100 Pavia, Italy Federico Pirzio, INFN and Dipartimento di Elettronica dell’Università di Pavia, Via Ferrata 1, 27100 Pavia, Italy Antonio Agnesi, INFN and Dipartimento di Elettronica dell’Università di Pavia, Via Ferrata 1, 27100 Pavia, Italy Giancarlo Reali, INFN and Dipartimento di Elettronica dell’Università di Pavia, Via Ferrata 1, 27100 Pavia, Italy Valentin Petrov, Max-Born-Institute for Nonlinear Optics and Ultrafast Spectroscopy, 2A, Max-Born-Str, 12489 Berlin, Germany Aleksey Tyazhev, Max-Born-Institute for Nonlinear Optics and Ultrafast Spectroscopy, 2A, Max-Born-Str, 12489 Berlin, Germany Valdas Pasiskevicius, Department of Applied Physics, Royal Institute of Technology, 10691 Stockholm, Sweden Nicky Thilmann, Department of Applied Physics, Royal Institute of Technology, 10691 Stockholm, Sweden Fredrik Laurell, Department of Applied Physics, Royal Institute of Technology, 10691 Stockholm, Sweden Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Experimental results of the implementation of our concept of neutral gain modules (NGM) in high-power thin-disk lasers are presented. To demonstrate power scalability and high brightness, series of NGMs comprising up to four Yb:YAG thin-disk laser modules have been integrated in various ways into stable and unstable resonators. Furthermore, to compensate for the parabolic component of the remaining thermal lens effects in the high-power regime, an intracavity deformable mirror was embedded. On the basis of the underlying concept, in our experiments an output power of nearly 3 kW with a beam propagation factor M 2 = 5 as well as a brightness up to B = 21  GW / cm 2   sr could be demonstrated. Compensating systematically for the nonparabolic components of the phase aberrations, the concept also enables a further enhancement of the beam quality. The principle is transferable to other laser configurations, e.g., master oscillator power amplifier systems. Content Type Journal Article Pages 1-14 DOI 10.1007/s00340-012-5174-7 Authors J. Mende, German Aerospace Center, Institute of Technical Physics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany G. Spindler, German Aerospace Center, Institute of Technical Physics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany T. Hall, German Aerospace Center, Institute of Technical Physics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany E. Schmid, German Aerospace Center, Institute of Technical Physics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany J. Speiser, German Aerospace Center, Institute of Technical Physics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany A. Giesen, German Aerospace Center, Institute of Technical Physics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We developed a sol–gel method using the dressed photon–phonon (DPP) process. DPPs are selectively exited in nanoscale structures at photon energies that are lower than the bandgap energy, which allows one to increase the growth rate of smaller ZnO quantum dots (QDs). Thus, we obtained a smaller size variance of ZnO QDs. The growth rate was proportional to the power of the light used for DPP excitation. The results were confirmed using a rate equation that accounted for the concentration of the sol–gel solution. Content Type Journal Article Category Rapid Communication Pages 1-5 DOI 10.1007/s00340-012-5151-1 Authors Y. Liu, Department of Electrical Engineering and Information Systems, School of Engineering, The University of Tokyo, Tokyo, 113-8656 Japan T. Yatsui, Department of Electrical Engineering and Information Systems, School of Engineering, The University of Tokyo, Tokyo, 113-8656 Japan M. Ohtsu, Department of Electrical Engineering and Information Systems, School of Engineering, The University of Tokyo, Tokyo, 113-8656 Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Efficient upconversion of photoluminescence from donor-bound excitons is revealed in bulk and nanorod ZnO. Based on excitation power-dependent PL measurements performed with different energies of excitation photons, two-photon absorption (TPA) and two-step TPA (TS-TPA) processes are concluded to be responsible for the upconversion. The TS-TPA process is found to occur via a defect/impurity (or defects/impurities) with an energy level (or levels) lying within 1.14–1.56 eV from one of the band edges, without involving photon recycling. One of the possible defect candidates could be V Zn . A sharp energy threshold, different from that for the corresponding one-photon absorption, is observed for the TPA process and is explained in terms of selection rules for the involved optical transitions. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5138-y Authors S. L. Chen, Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden J. Stehr, Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden N. Koteeswara Reddy, Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, 500712 Republic of Korea C. W. Tu, Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology, Gwangju, 500712 Republic of Korea W. M. Chen, Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden I. A. Buyanova, Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We observed a high strength near-infrared luminescence in Bi-doped KAlCl 4 polycrystalline material. Luminescence dependence on the excitation wavelength and temperature of the sample was studied. Our experimental results allow asserting that the luminescence peaked near 1 μm belongs solely to Bi + ion which isomorphically substitutes potassium in the crystal. It was also demonstrated that Bi + luminescence features strongly depend on the local ion surroundings. Content Type Journal Article Category Rapid Communication Pages 1-4 DOI 10.1007/s00340-012-5145-z Authors A. A. Veber, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, 38 Vavilov Str., 119991 Moscow, Russia A. N. Romanov, Research Computer Center, M.V. Lomonosov Moscow State University, 1 Leninskie Gory, Build. 4, 119992 Moscow, Russia O. V. Usovich, Department of Chemistry, M.V. Lomonosov Moscow State University, 1 Leninskie Gory, Build. 3, 119991 Moscow, Russia Z. T. Fattakhova, N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4 Kosygina Str., 119991 Moscow, Russia E. V. Haula, N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4 Kosygina Str., 119991 Moscow, Russia V. N. Korchak, N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4 Kosygina Str., 119991 Moscow, Russia L. A. Trusov, Department of Chemistry, M.V. Lomonosov Moscow State University, 1 Leninskie Gory, Build. 3, 119991 Moscow, Russia P. E. Kazin, Department of Chemistry, M.V. Lomonosov Moscow State University, 1 Leninskie Gory, Build. 3, 119991 Moscow, Russia V. B. Sulimov, Research Computer Center, M.V. Lomonosov Moscow State University, 1 Leninskie Gory, Build. 4, 119992 Moscow, Russia V. B. Tsvetkov, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, 38 Vavilov Str., 119991 Moscow, Russia Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    In this work, we study the limitations for overcoming the longitudinal piston error in a femtosecond tiled-grating compressor using nonlinear measurements like second harmonic generation. In particular, we observe the influence of this error when developing high-power laser experiments such as high-order harmonic generation. The generation of nonlinear processes with femtosecond pulses compressed in tiled-grating systems is studied. Special attention is paid to the role of the longitudinal piston error which is the most difficult to overcome in the compressor alignment. A complex spatio-temporal structure is expected to appear due to that misalignment. Both second harmonic generation in nonlinear crystals and high-order harmonic generation in gases are studied and a strong dependence with piston error is found, thus leading to a sub-micron modulation in the generated signal. In particular, the high sensitivity of the high-order harmonics to the longitudinal position allows one to use this processes for the accurate alignment of the compressor to few tens of nanometers. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5137-z Authors C. Hernández-García, Grupo de Investigación en Óptica Extrema, Universidad de Salamanca, E-37008 Salamanca, Spain C. Méndez, Centro de Láseres Pulsados, CLPU, E-37008 Salamanca, Spain I. Arias, Grupo de Investigación en Óptica Extrema, Universidad de Salamanca, E-37008 Salamanca, Spain J. R. Vázquez de Aldana, Grupo de Investigación en Microprocesado de Materiales con Láser, Universidad de Salamanca, E-37008 Salamanca, Spain O. Varela, Centro de Láseres Pulsados, CLPU, E-37008 Salamanca, Spain I. J. Sola, Grupo de Investigación en Óptica Extrema, Universidad de Salamanca, E-37008 Salamanca, Spain L. Roso, Centro de Láseres Pulsados, CLPU, E-37008 Salamanca, Spain Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We demonstrate the realization of narrow linewidth, high-power ridge waveguide DFB diode lasers emitting near 780 nm. The effects of the coupling coefficient, the laser chip length, and the fabrication process onto the spectral linewidth are discussed. By optimizing both the cavity length and the coupling coefficient, we achieve an intrinsic spectral linewidth as small as 35 kHz at an output power of 270 mW. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5131-5 Authors T.-P. Nguyen, Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany M. Schiemangk, Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr. 15, 12489 Berlin, Germany S. Spießberger, Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany H. Wenzel, Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany A. Wicht, Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany A. Peters, Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany G. Erbert, Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany G. Tränkle, Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We experimentally studied the temporal coherence of stimulated Brillouin scattering (SBS) excited by a single-longitude-mode laser. We found that the temporal coherence of SBS is variable but not fixed. In a certain range above the threshold pump energy in which the pulse of the Stokes component is Fourier limited, the coherence length is considerably long, although the temporal coherence decreases with increasing pulse compression rate. If the Fourier transform condition is not satisfied for the pulse of the Stokes component, the temporal coherence decreases rapidly, and the coherence length is much shorter. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5123-5 Authors Lei Zhang, Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hang Kong University, Nanchang, 330063 China Dong Zhang, Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hang Kong University, Nanchang, 330063 China Jiulin Shi, Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hang Kong University, Nanchang, 330063 China Jinwei Shi, Applied Optics Beijing Area Major Laboratory, Department of Physics, Beijing Normal University, Beijing, 100875 China Wenping Gong, Applied Optics Beijing Area Major Laboratory, Department of Physics, Beijing Normal University, Beijing, 100875 China Dahe Liu, Key Laboratory of Nondestructive Test (Ministry of Education), Nanchang Hang Kong University, Nanchang, 330063 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We theoretically show that a family of optical beams with vortex-lattice structures can be reliably generated by tilting the focal lens to introduce the relative phases between the interfering beams. We also experimentally generate the quasicrystal beams to confirm the theoretical analysis. With the analytical wave functions and experimental patterns, a variety of vortex-lattice structures are manifested. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5179-2 Authors J. C. Tung, Department of Electrophysics, National Chiao Tung University, 1001 TA Hsueh Road, 30010 Hsinchu, Taiwan H. C. Liang, Department of Electrophysics, National Chiao Tung University, 1001 TA Hsueh Road, 30010 Hsinchu, Taiwan C. H. Tsou, Department of Electrophysics, National Chiao Tung University, 1001 TA Hsueh Road, 30010 Hsinchu, Taiwan K. W. Su, Department of Electrophysics, National Chiao Tung University, 1001 TA Hsueh Road, 30010 Hsinchu, Taiwan Y. F. Chen, Department of Electrophysics, National Chiao Tung University, 1001 TA Hsueh Road, 30010 Hsinchu, Taiwan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We present a study of the spectral and angular dependence of scattered mid-infrared light from surfaces coated with explosives residues (TNT, RDX, and tetryl) detected at a 2 m standoff distance. An external cavity quantum cascade laser provided tunable illumination between 7 and 8 μm. Important differences were identified in the spectral features between specular reflection and diffuse scattering which will impact most practical testing scenarios and complicate material identification. We discuss some of the factors influencing the dependence of observed spectra on the experimental geometry. Content Type Journal Article Pages 1-10 DOI 10.1007/s00340-012-5134-2 Authors Jonathan D. Suter, Pacific Northwest National Laboratory, K5-25, PO Box 999, Richland, WA 99352, USA Bruce Bernacki, Pacific Northwest National Laboratory, K5-25, PO Box 999, Richland, WA 99352, USA Mark C. Phillips, Pacific Northwest National Laboratory, K5-25, PO Box 999, Richland, WA 99352, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    In this manuscript, the principle of single frequency dithering technique in multi-channel coherent polarization beam combining (CPBC) system is analyzed systematically and its feasibility for multi-tone and multi-channel is experimentally verified. In each laser channel, two spectrally combined single-frequency seed lasers are employed, which has the potential ability to alleviate the stimulated Brillouin scattering (SBS) effect in high power master oscillator power amplifier (MOPA) system. A simple and robust single frequency dithering technique is used to active phase-lock the four laser beams. When the system is in the closed loop, the phase noise can be suppressed effectively and the efficiency of the whole CPBC system can be as high as 92 %. The scheme can be scaled to multiple channels without adding complexity for phase control. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-012-5187-2 Authors Pengfei Ma, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China Pu Zhou, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China Yanxing Ma, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China Rongtao Su, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China Xiaojun Xu, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China Zejin Liu, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    P–n junction GaN light-emitting diodes (LEDs) were fabricated using Ga-doped ZnO (GZO) films as electrical contacts and characterized by electroluminescence (EL) and current–voltage (I–V) measurements. GaN p–n epilayers with a total thickness of ~6 μm were grown on c-plane (0001) sapphire substrates by metal–organic chemical vapor deposition. Half region of the p-GaN layer was etched until the n-GaN layer was exposed, and 100-nm-thick GZO contacts were deposited on the p- and n-GaN layers by RF sputtering with varying Ga concentration ( n G ) from 1 to 5 mol%. Based on the results of Hall effect, photoluminescence (PL), and X-ray diffraction (XRD), the GZO films were expected to act as best electrical contacts for the LEDs at n G  = 2 mol%. Under forward-bias conditions, the I–V curves showed diode characteristics except n G  = 5 mol%, and the leakage current was minimized at n G  = 2 mol%. Two dominant EL peaks of ultraviolet and yellow emissions were observed at ~376 and ~560 nm, and attributed to near-band-edge- and defect-related radiative transitions, respectively. At n G  = 2 mol%, the UV EL showed markedly large intensities for all injection currents, consistent with the results of Hall effect, PL, I–V, and XRD. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5129-z Authors Chang Oh Kim, Department of Applied Physics and Regional Innovation Center, Kyung Hee University, Yongin, 446-701 Korea Sung Kim, Department of Applied Physics and Regional Innovation Center, Kyung Hee University, Yongin, 446-701 Korea Dong Hee Shin, Department of Applied Physics and Regional Innovation Center, Kyung Hee University, Yongin, 446-701 Korea Dong Yeol Shin, Department of Applied Physics and Regional Innovation Center, Kyung Hee University, Yongin, 446-701 Korea Suk-Ho Choi, Department of Applied Physics and Regional Innovation Center, Kyung Hee University, Yongin, 446-701 Korea Sung Won Hwang, Samsung LED Co., Ltd., 314, Maetan 3-dong, Yeongtong-gu, Suwon, 443-743 Korea Nam-Goo Cha, Samsung LED Co., Ltd., 314, Maetan 3-dong, Yeongtong-gu, Suwon, 443-743 Korea Sammook Kang, Samsung LED Co., Ltd., 314, Maetan 3-dong, Yeongtong-gu, Suwon, 443-743 Korea Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We demonstrate a method combining laser ionization of molecules with projection technique and allowing observation of photoionization processes in gases with sub-focal spatial micro-resolution. A bunch of molecular ions created by the nonlinear photoionization of the imaging gas near a tip extends in a divergent electrostatic field producing a magnifying image on the detector. It can be used to observe the profile of the sharply-focused intense laser beam in a wide spectral range. In proof of principle experiment the water molecules are ionized in ~40-μm laser focal spot in the vicinity of the silver needle with a curvature radius 0.5 mm and the resultant ions are counted by a position-sensitive scheme. According to our estimations, ~1.5-μm spatial resolution has been reached. Using a sharp tip, the spatial resolution can be improved to the sub-micrometer scale and such approach can be applied for short wavelength beam diagnostics. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-012-5136-0 Authors S. A. Aseyev, Institute of Spectroscopy RAS, Troitsk, Moscow, 142190 Russia V. G. Minogin, Institute of Spectroscopy RAS, Troitsk, Moscow, 142190 Russia B. N. Mironov, Institute of Spectroscopy RAS, Troitsk, Moscow, 142190 Russia Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A new experimental method is described enabling detection of hydroxyl radicals (OH) by laser-induced fluorescence in high-temperature gas-phase reactions. This is accomplished by means of a bidirectional optical fiber probe, which is of interest for applications where optical access is limited. An optical setup that allows simultaneous excitation and detection of fluorescence using one and the same fiber has been developed. Complications resulting from coupling as well as laser-induced scattering are addressed, and different fibers are compared with regard to core material composition and geometric collection efficiency. On this basis, a suitable fiber is identified, and OH detection and profile measurements are demonstrated in a premixed laminar flame as reference experiment. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5172-9 Authors Heiner Schwarz, Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4–6, 14195 Berlin, Germany Robert Schlögl, Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4–6, 14195 Berlin, Germany Raimund Horn, Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4–6, 14195 Berlin, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Plane EM waves transmitted through nano-corrugated metallic thin films produce evanescent waves which include the information on the nano-structures. The production of the evanescent waves at the metallic surface is analyzed. A microsphere located above the metallic surface collects the evanescent waves which are converted into propagating waves. The equations for the refraction at the boundary of the microsphere and the use of Snell’s law for evanescent waves are developed. The magnification of the nano-structure images is explained by a geometric optics description, but the high resolution is related to the evanescent waves properties. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5193-4 Authors Y. Ben-Aryeh, Physics Department, Technion–Israel Institute of Technology, Haifa, 32000 Israel Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Active waveguides with high surface roughness due to phase separation in polymer blends can sustain wave-guided coherent random lasing, paving way to the development of integrated devices technologically and economically more favorable that the ones based on nanopatterning. In spite of the vast amount of work on organic thin film lasers carried out, the orange-red spectral region (600–700 nm) has not received much attention in this context, albeit it is of interest in biophotonic applications. In this paper, wave-guided coherent random lasing (RL) at 610 nm (Sulforhodamine B) and 630 nm (Sulforhodamine 640) is achieved by incorporating silsesquioxane nanoparticles into dye-doped polymer films. An AFM analysis concludes that the RL emission originates due to the scattering induced by the high surface roughness coming from the polymer/silsesquioxane phase separation. The reported results demonstrate that it is possible to get efficient and photostable laser emission from dye-doped thin films in the wavelength region over 600 nm by incorporating into the polymeric material appropriate nanoparticles which induce structural changes. Content Type Journal Article Pages 1-12 DOI 10.1007/s00340-012-5120-8 Authors Luis Cerdán, Instituto de Química Física “Rocasolano” (CSIC), Serrano 119, 28006 Madrid, Spain Angel Costela, Instituto de Química Física “Rocasolano” (CSIC), Serrano 119, 28006 Madrid, Spain Gonzalo Durán-Sampedro, Instituto de Química Física “Rocasolano” (CSIC), Serrano 119, 28006 Madrid, Spain Inmaculada García-Moreno, Instituto de Química Física “Rocasolano” (CSIC), Serrano 119, 28006 Madrid, Spain Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Two miniaturized Raman measurement heads containing microsystem diode lasers emitting at 783 and 671 nm suitable for shifted excitation Raman difference spectroscopy (SERDS) were applied for the non-invasive in situ differentiation of selected meat species. This allows using the fingerprint characteristics of Raman spectra without a disturbing fluorescence background. At 783 nm, two emission lines with a spectral shift of 0.5 nm (7 cm −1 ) and optical powers of up to 110 mW were realized. For 671 nm excitation, the spectral shift amounts to 0.6 nm (12 cm −1 ) and optical powers of up to 40 mW were obtained. In both cases, meat Raman spectra could be recorded with integration times of 10 s. The investigations were carried out using selected cuts from the most commonly consumed meat species in the US and Europe, i.e. beef, pork, chicken, and turkey. A principal components analysis of the SERDS spectra revealed a clear separation of the meat species into four distinct groups for both excitation wavelengths. This classification is based on the myoglobin content and gradual differences of protein Raman band intensities and positions. The results demonstrate the potential of SERDS as rapid and non-destructive screening method for the discrimination of selected meat species. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-012-5160-0 Authors Kay Sowoidnich, Institut für Optik und Atomare Physik, Technische Universität Berlin, Sekr. EW 0-1, Hardenbergstraße 36, 10623 Berlin, Germany Heinz-Detlef Kronfeldt, Institut für Optik und Atomare Physik, Technische Universität Berlin, Sekr. EW 0-1, Hardenbergstraße 36, 10623 Berlin, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Polarization splitting wavelength-selective characteristics of Au-filled high-birefringence photonic crystal fiber (HB-PCF) based on the finite element method is investigated. Numerical results show that the polarization splitting effect can be observed in metal-filled HB-PCF. The resonances points and strength in two polarizations can be adjusted by changing the fiber birefringence, the pitch between the adjacent air holes and the size of the metal wires. Finally, two kinds of Au-filled HB-PCFs with completely polarization splitting and filtering characteristics in communication wavelength are designed. Results show that this polarization splitting effect in metal-filled HB-PCF is very useful for further studies in polarization-dependent wavelength-selective applications and other fiber-based plasmonic devices. Content Type Journal Article Pages 1-10 DOI 10.1007/s00340-012-5163-x Authors Y. Du, Key Laboratory of Metastable Materials Science and Technology, College of Science, Yanshan University, Qinhuangdao, 066004 People’s Republic of China S.-G. Li, Key Laboratory of Metastable Materials Science and Technology, College of Science, Yanshan University, Qinhuangdao, 066004 People’s Republic of China S. Liu, Key Laboratory of Metastable Materials Science and Technology, College of Science, Yanshan University, Qinhuangdao, 066004 People’s Republic of China X.-P. Zhu, Key Laboratory of Metastable Materials Science and Technology, College of Science, Yanshan University, Qinhuangdao, 066004 People’s Republic of China X.-X. Zhang, Key Laboratory of Metastable Materials Science and Technology, College of Science, Yanshan University, Qinhuangdao, 066004 People’s Republic of China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The room-temperature response of a 10-MHz quadrant avalanche photodiode (APD) is investigated for detection of high frequency oscillations and tip displacements of fabricated microcantilevers. Currently, no quadrant detectors with a response bandwidth in the megahertz range are available, and oscillations on the order of a few microseconds cannot be resolved. A comparison is made between optical and opto-mechanical measurements to characterize this detector by investigating the frequency response and signal-to-noise (SNR) of pulsed laser signals up to 10 MHz and reflected laser signals from freely vibrating microcantilevers up to 1.64 MHz. The power level of the minimum detectable signal incident on the APD is found to be 28.2 ± 5.0 nW for optical measurements and 1.0 μW ± 5.0 nW for opto-mechanical measurements. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5162-y Authors Brian G. Burke, Ceramics Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA David A. LaVan, Ceramics Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    In phase-shifting interferometry, based on the difference image between interferograms with unknown phase-shifting amount, a rapid phase extraction method is proposed. In this method, first, by means of the simple subtraction operation between interferograms captured in one phase-shifting period, a sequence of difference images are generated easily; second, to decrease the random phase-shifting errors induced during the phase-shifting procedure, the summation operation is performed for these difference images; third, based on one time phase recovery operation and one time phase-unwrapping operation, the measured phase with high precision can be obtained rapidly. Moreover, in the proposed method, by means of a simple phase summation operation for all pixel-phases in one interferogram, the corresponding phase-shifting amount of interferogram can be determined conveniently. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-012-5195-2 Authors Fengjie Zhang, Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou, 510006 Guangdong, China Liyun Zhong, Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou, 510006 Guangdong, China Shengde Liu, Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou, 510006 Guangdong, China Xiaoxu Lu, Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou, 510006 Guangdong, China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A technique of enhancing and broadening terahertz (THz) wave radiation from large aperture photoconductive (PC) antenna is presented in this paper. In this technique, the PC antenna is excited by both the optical and previously generated THz pulses by a laser-induced air plasma created in front of PC antenna and an enhanced and broadened THz wave signal is obtained. The theoretical and experimental investigation shows that the superposition is the main mechanism for this enhancement. The technique shown in this paper can be very useful for THz imaging and spectroscopy. Content Type Journal Article Pages 1-4 DOI 10.1007/s00340-012-5116-4 Authors Yaohui Gao, Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA Chia-En Yang, Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA Yunching Chang, Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA Jimmy Yao, Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA Stuart Yin, Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA Claire Luo, General Opto Solutions, LLC, State College, PA 16802, USA Paul Ruffin, US Army Aviation and Missile Research Development and Engineering Center, Redstone Arsenal, AL 35898, USA Christina Brantley, US Army Aviation and Missile Research Development and Engineering Center, Redstone Arsenal, AL 35898, USA Eugene Edwards, US Army Aviation and Missile Research Development and Engineering Center, Redstone Arsenal, AL 35898, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171