ALBERT

Description: In this work, we present suitable phase accuracy indicators, which are obtained from the first three obtained eigenvalues of the principal component analysis (PCA) demodulation algorithm. These indicators can be used in the measuring process to determine a blind phase goodness assessment, without the need of using any ground truth phase information. Therefore, it is possible to perform further actions if required, as obtaining more interferograms or repeat the measure. Additionally, we present simulated and experimental results that support our mathematical analysis and conclusions. A complete MATLAB software package reproducing any result and figure shown in this work is provided in ( http://goo.gl/fy5EC ).

Description: We propose the use of graded-index few-mode fibers for mode conversion by long-period gratings (LPG) transiently written by ultrashort laser pulses using the optical Kerr effect. The mode interaction is studied by numerically solving the multi-mode coupled nonlinear Schrödinger equations. We present highly efficient conversion of the LP 01 - into the LP 11 -mode preserving the pulse shape in contrast to previous results in step-index fibers. Furthermore, mode conversion using different wavelengths for inducing and probing the LPG is shown. Due to the flat phase-matching curve of the examined modes in the graded-index fiber, mode conversion can be observed for probe center wavelengths of 1,100 nm up to 1,800 nm with a write beam centered around 1,030 nm. Therefore, a complete separation of the probe from the write beam should be possible as well as the application of optically induced guided-mode conversion for all-optical modulation across a broad wavelength range.

Description: Laser-induced fluorescence of anisole as tracer of isooctane at an excitation wavelength of 266 nm was investigated for conditions relevant to rapid compression machine studies and for more general application of internal combustion engines regarding temperature, pressure, and ambient gas composition. An optically accessible high pressure and high temperature chamber was operated by using different ambient gases (Ar, N 2 , CO 2 , air, and gas mixtures). Fluorescence experiments were investigated at a large range of pressure and temperature (0.2–4 MPa and 473–823 K). Anisole fluorescence quantum yield decreases strongly with temperature for every considered ambient gas, due to efficient radiative mechanisms of intersystem crossing. Concerning the pressure effect, the fluorescence signal decreases with increasing pressure, because increasing the collisional rate leads to more important non-radiative collisional relaxation. The quenching effect is strongly efficient in oxygen, with a fluorescence evolution described by Stern–Volmer relation. The dependence of anisole fluorescence versus thermodynamic parameters suggests the use of this tracer for temperature imaging in specific conditions detailed in this paper. The calibration procedure for temperature measurements is established for the single-excitation wavelength and two-color detection technique.

Description: A core-mode Fabry–Perot (FP) interferometer is constructed by using a dual-core photonic crystal fiber (DCPCF). The FP cavity is formed by a single piece of DCPCF, which can also serve as a direct sensing probe without any additional components. We theoretically and experimentally studied its temperature responses in the range of 40–480 °C. The temperature sensitivity is 13 pm/°C which matches the theoretical results. Since the temperature sensitivity of the proposed sensor is independent on cavity length, precise control of the length of FP cavity or photonic crystal fiber is not required. The sensor size can be as short as 100–200 μm, and its fabrication only involves splicing and cleaving, which make the sensor production very cost-effective. The proposed FP interferometric sensor based on a DCPCF can find applications in high-temperature measurement especially those that need accurate point measurement with high sensitivity.

Description: We present measurements of the absorption and emission cross-sections for Yb:YAG , Yb:LuAG and Yb:CaF 2 as a function of temperature between 80 and 340 K. The cross-sections are determined by the combination of the McCumber relation and the Fuchtbauer–Ladenburg (FL) equation to achieve reliable results in spectral regions of high and low absorption. The experimental setup used for the fluorescence measurements minimizes re-absorption effects due to the measurement from small sample volume, providing nearly undisturbed raw data for the FL approach. The retrieved cross-sections together with the spectral characteristics of the tested materials provide important information for the design of energy efficient, high-power laser amplifiers.

Description: An asymmetric chiral metamaterial (CMM) circular polarizer based on bilayer twisted split-ring resonator structure was proposed and investigated. Both numerical simulations and experiments reveal that when a y -polarized wave is incident on this CMM propagating along backward (− z ) direction, the two linear components of the transmitted wave have nearly equal amplitudes and 90°(−90°) phase difference at the resonant frequencies. This means that the right-hand circular polarization and left-hand circular polarization are realized in transmission at 6.4 and 8.1 GHz, respectively. The surface current distributions are studied to illustrate the transformation behavior for both circular polarizations. Further, the influences of the structural parameters of the circular polarizer to the transformation transmissions spectra have been investigated numerically.

Description: A tunable multiwavelength Brillouin-erbium fiber laser (MW-BEFL) using a twin-core fiber (TCF) coupler is proposed and demonstrated. The TCF coupler is formed by splicing a section of TCF between two single-mode fibers. By simply applying bending curvature on the TCF coupler, the peak net gain is shifted close to the Brillouin pump (BP), which has advantage for suppressing self-lasing cavity modes with low-BP-power injection. In this work, the dependency of the Stokes signals tuning range on the free spectral range (FSR) of TCF coupler is studied. It is also found that the tuning range of MW-BEFL can exceed the FSR of TCF coupler by adopting proper BP power and 980-nm pump power. Up to 40 nm tuning range of MW-BEFL in the absence of self-lasing cavity modes is achieved.

Description: The high-precise star sensor calibration method requires high-accurate turntable, collimator, star point plate or other high-precision devices that are very expensive. We present a simple and available method to calibrate the principal point, focal length, radial distortion, tangential distortion and installation error of star sensor in laboratory, and without having high accurate or expensive devices. The calibration model takes the ordinary camera calibration methods and installation error into account. The installation error is modeled by combination of three typical effects: the installation of pan-tilt-zoom (PTZ) initial status, PTZ and charge-coupled device, which result in six parameters. The proposed procedure consists of a closed-form solution, followed by a nonlinear refining based on maximum likelihood criterion. Our calibration method is validated through simulation and real data that shows the superiority with respect to the traditional methods and has the same level as the state-of-the-art methods. The accuracy of our calibration method is 0.015° in the root of mean square distances between testing points and projected ones.

Description: We report on the development of semiconductor double-chirped mirrors with the group delay dispersion of −3,800 ± 100 fs 2 in the wavelength range between 1,058 ÷ 1,064 nm and reflectivity of 99.1 %. The simplified plane-wave reflection transfer method was used to design the mirror multilayer stack. The mirror contains an epitaxial AlAs/GaAs structure topped with a SiNx antireflective layer.

Description: There is significant need for optical diagnostic techniques to measure instantaneous volumetric vector and scalar distributions in fluid flows and combustion processes. This is especially true for investigations where only limited optical access is available, such as in internal combustion engines, furnaces, flow reactors, etc. While techniques such as tomographic PIV for velocity measurement have emerged and reached a good level of maturity, instantaneous 3D measurements of scalar quantities are not available at the same level. Recently, developments in light field technology have progressed to a degree where implementation into scientific 3D imaging becomes feasible. Others have already demonstrated the utility of light field technology toward imaging high-contrast particles for PIV and for imaging flames when treated as single-surface objects. Here, the applicability and shortcomings of current commercially available light field technology toward volumetric imaging of translucent scalar distributions and flames are investigated. Results are presented from imaging canonical chemiluminescent and laser-induced fluorescent systems. While the current light field technology is able to qualitatively determine the position of surfaces by locating high-contrast features, the correlation-based reconstruction algorithm is unable to fully reconstruct the imaged objects for quantitative diagnostics. Current analysis algorithms are based on high-contrast correlation schemes, and new tools, possibly based on tomographic concepts, will have to be implemented to reconstruct the full 3D structure of translucent objects for quantitative analysis.

Description: We describe laser systems for photoionization, Doppler cooling, and quantum state manipulation of beryllium ions. For photoionization of neutral beryllium, we have developed a continuous-wave 235 nm source obtained by two stages of frequency doubling from a diode laser at 940 nm. The system delivers up to 400 mW at 470 nm and 28 mW at 235 nm. For control of the beryllium ion, three laser wavelengths at 313 nm are produced by sum-frequency generation and second-harmonic generation from four infrared fiber lasers. Up to 7.2 W at 626 nm and 1.9 W at 313 nm are obtained using two pump beams at 1051 and 1551 nm. Intensity drifts of around 0.5 % per hour have been measured over 8 h at a 313 nm power of 1 W. These systems have been used to load beryllium ions into a segmented ion trap.

Description: A novel approach to mass measurements at the 10 −9 level for short-lived nuclides with half-lives well below one second is presented. It is based on the projection of the radial ion motion in a Penning trap onto a position-sensitive detector. Compared with the presently employed time-of-flight ion-cyclotron-resonance technique, the novel approach is 25-times faster and provides a 40-fold gain in resolving power. Moreover, it offers a substantially higher sensitivity since just two ions are sufficient to determine the ion’s cyclotron frequency. Systematic effects specific to the technique that can change the measured cyclotron frequency are considered in detail. It is shown that the main factors that limit the maximal accuracy and resolving power of the technique are collisions of the stored ions with residual gas in the trap, the temporal instability of the trapping voltage, the anharmonicities of the trapping potential and the uncertainty introduced by the conversion of the cyclotron to magnetron motion.

Description: The kinetics of signal formation in collinear photofragmentation and atomic absorption spectroscopy (CPFAAS) are discussed, and theoretical equations describing the relation between the concentration of the target molecule and the detected atomic absorption in case of pure and impure samples are derived. The validity of the equation for pure samples is studied experimentally by comparing measured target molecule concentrations to concentrations determined using two other independent techniques. Our study shows that CPFAAS is capable of measuring target molecule concentrations from parts per billion (ppb) to hundreds of parts per million (ppm) in microsecond timescale. Moreover, the possibility to extend the dynamic range to cover eight orders of magnitude with a proper selection of fragmentation light source is discussed. The maximum deviation between the CPFAAS technique and a reference measurement technique is found to be less than 5 %. In this study, potassium chloride vapor and atomic potassium are used as a target molecule and a probed atom, respectively.

Description: The photorefractive (PR) properties of semi-insulating GaAs/AlGaAs multiple quantum wells (MQWs) operating in the Franz–Keldysh geometry are modelled by solving the material equations including the nonlinear transport of hot electrons. This work studies the PR response of MQWs in a two-wave mixing geometry under a moving grating. Calculations were made under the small intensity modulation approximation, and the simulation results are compared with experimental data available in the literature. A reasonable qualitative agreement regarding most experimental characteristics was found. The results can be treated as a test of the correctness of the commonly used band transport model of PR behaviour in MQWs. Analytic solutions for the stationary and transient regimes under negligible diffusion are given. In addition, the conditions for the occurrence of a strong resonance predicted by the model are noted.

Description: Molecular rotational states of nitrogen and oxygen molecules at room temperature and atmospheric pressure are excited by femtosecond double- and multi-pulses with variable temporal pulse distances, and quartz-enhanced photoacoustic spectroscopy is used for their detection. A simple extrapolation of measured double-pulse data is presented, which predicts form and position of Raman-excited spectral features and thus enables us to distinguish between spectral lines caused by Raman-scattering- and collision-induced absorption both appearing when excitation by pulse trains is used.

Description: An improved method that has the potential to improve the retrieval of aerosol optics properties (backscatter/extinction coefficients) from elastic–Raman lidar data is presented. Aerosol backscatter coefficients can be retrieved by choosing the reference height at near-range rather than conventional far-range when the signal-to-noise ratios are low at the far-range or aloft aerosol layers and clouds appear there. Significant retrieval errors in aerosol backscatter coefficients caused by large uncertainties of the aerosol reference value at far-range can be reduced. To avoid the ill-posed retrievals of aerosol extinction from the conventional Raman method, the new method derives the aerosol extinction and lidar ratio with the constrained Fernald inversions by independent aerosol backscatter coefficients from above proposed method. The numerical simulations demonstrated that the proposed method provides good accuracy and resolution of aerosol profile retrievals. And the method is also applied to elastic–Raman lidar measurements at the Hampton University, Hampton, Virginia.

Description: Tunable diode laser absorption spectroscopy based in situ sensors for CO (2.33 μm), CO 2 (2.02 μm), CH 4 (2.29 μm) and H 2 O (1.35 μm) were deployed in a pilot-scale (1 ton/day), high-pressure (up to 18 atm), entrained flow, oxygen-blown, slagging coal gasifier at the University of Utah. Measurements of species mole fraction with 3-s time resolution were taken at the pre- and post-filtration stages of the gasifier synthesis gas (called here syngas) output flow. Although particulate scattering makes pre-filter measurements more difficult, this location avoids the time delay of flow through the filtration devices. With the measured species and known N 2 concentrations, the H 2 content was obtained via balance. The lower heating value and the Wobbe index of the gas mixture were estimated using the measured gas composition. The sensors demonstrated here show promise for monitoring and control of the gasification process.

Description: Modulation instability can be used to convert a continuous light wave into a train of pulses on a constant background. It is a longstanding discussion whether these pulses can be converted into solitons. We clarify the situation by using a more general mathematical context, invoking the Akhmediev breather, Peregrine soliton and Kuznetsov-Ma soliton solutions of the wave equation, and suggest the use of a Mach–Zehnder interferometer to remove the background. Expressions for the pulse widths and peak powers thus obtained are presented, and their soliton content is determined. It turns out that more than 95 % of each pulse’s energy can be converted to a soliton.

Description: We propose an optodynamical model of interaction of pulsed laser radiation with aggregates of spherical metallic nanoparticles embedded into host media. The model takes into account polydispersity of particles, pair interactions between the particles, dissipation of absorbed energy, heating and melting of the metallic core of particles and of their polymer adsorption layers, and heat exchange between electron and ion components of the particle material as well as heat exchange with the interparticle medium. Temperature dependence of the electron relaxation constant of the particle material and the effect of this dependence on interaction of nanoparticles with laser radiation are first taken into consideration. We study in detail light-induced processes in the simplest resonant domains of multiparticle aggregates consisting of two particles of an arbitrary size in aqueous medium. Optical interparticle forces are realized due to the light-induced dipole interaction. The dipole moment of each particle is calculated by the coupled dipole method (with correction for the effect of higher multipoles). We determined the role of various interrelated factors leading to photomodification of resonant domains and found an essential difference in the photomodification mechanisms between polydisperse and monodisperse nanostructures.

Description: Ferroelectric domains are engineered in lithium niobate crystals by scanning strongly absorbed UV laser light across the crystal surface. Focused UV laser light can not only write, but also erase previously written domains on the non-polar faces of lithium niobate, which allows tailoring of domain patterns. Such domain pattern was generated and afterward investigated by piezoresponse force microscopy and hydrofluoric acid etching. It was found that domains with dimensions down to 2 μm can be engineered, which was ∼30 % of the focus beam diameter (7 μm) used for writing the domains. Additionally, it was found that an unique domain depth profile can be formed, which is inclined to the crystallographic axes and can be described as ‘half-crescent-shaped’.

Description: An eigenvalue method is proposed to study the threshold behaviors of plasmonic nano-lasers. The medium gain and dispersion are taken into consideration based on semi-classical laser dynamics, and therefore the lasing threshold, mode pattern, and lasing frequency can be theoretically predicted. The lasing properties of dielectric, plasmonic core, and plasmonic shell nano-lasers are investigated in details. It is found that the lasing thresholds of nano-lasers can be reduced by two orders of magnitude when introducing localized surface plasmon modes.

Description: We experimentally and theoretically investigate that detection sensitivity in surface plasmon resonance (SPR) biosensors can be significantly enhanced by employing subwavelength dielectric gratings deposited on a gold film. The enhancement originates from an improvement of field-matter interaction: enhanced evanescent field intensity at the binding region and increased surface reaction area. Using a large-area SiO 2 grating array fabricated by nanoimprint lithography, experimental sensor performance measured by parylene film coating shows that the SPR substrates combined with a dielectric grating provide a notable sensitivity improvement compared to a conventional bare gold film. We also demonstrate that plasmon field can be more confined and enhanced at the dielectric gratings with a larger width. The proposed SPR structure could potentially be useful in a variety of plasmonic applications including high-sensitivity biosensors.

Description: We show that the spin angular momentum (SAM) flux in a space-variant linearly polarized beam can be separated in the focal plane. Such a beam carries only orbital angular momentum (OAM) and develops a net SAM flux upon focusing. The radial splitting of the SAM flux density is mediated by the phase vortex (or OAM) and can be controlled by the topological charge of the phase vortex. Optical trapping experiments verify the separation of the SAM flux density. The proposed approach enriches the manipulation of the angular momentum of light fields and inspires more designs of focus engineering, which would benefit optical micromanipulation of microscopic particles.

Description: The mechanism of optical unidirectional (OUD) transmission in parallel subwavelength dual-metal gratings was investigated. It was found that this kind of OUD phenomenon originates from the coupling of the surface plasmon polaritons (SPPs) between the front grating and a layer of metal film which replaces the rear grating. The higher the intensity of the coupled SPPs at the entrances of the rear grating, the higher the transmittance can be achieved. Basing on this property, an effective OUD example was achieved by exploring the intensity difference at the entrances of the rear gratings between the two incidences of opposite directions. In this kind of OUD, the positive transmittance can exceed 80 % and the difference between the transmittances of the two opposite directions can be as large as 63 %. The detailed design process was also presented.

Description: Self-pulsing of continuous-wave Tm:YAlO 3 lasers limits their use for a variety of important applications. We demonstrate for the first time that the pulsing can be suppressed via feedback to the pump diode laser, a technique that is suitable for both external resonator and monolithic lasers. We also show that the optical transfer function of the laser is that of an unstable relaxation oscillator.

Description: We describe an efficient, low-threshold, continuous-wave (CW) and Q-switched operation of a Ho:YAG laser resonantly, single-pass pumped by a 20 W linearly polarized narrow line width Tm: fiber laser at the wavelength of 1,908 nm. At room temperature for an output coupler of 30 % transmission, a maximum continuous-wave output power of 13.3 W for 18.9 W of absorbed pump power was achieved, corresponding to a slope efficiency of 73 %. In a quasi continuous-wave pumping regime, for several output couplers slope efficiencies of almost 82 % were observed. For a Q-switched operation, a Brewster-cut acousto-optic modulator was used. In a CW pumping regime, the pulse repetition frequency (PRF) was changed from 4 to 15 kHz. Under a Q-switched operation, the maximum output power of 12.25 W in relation to 15 kHz PRF was obtained; however, the maximum peak power of almost 250 kW at the PRF of 4 kHz was demonstrated. In the best case, for 4 kHz PRF, pulse energies of 2.18 mJ with a 8.8 ns FWHM pulse width (one of the shortest pulse durations observed in holmium-doped Q-switched lasers) were achieved. The laser operated at the wavelength of 2,090.23 nm with the FWHM line width of 0.95 nm. The beam quality factor of M 2 was measured to be below 1.42 in both X and Y axis.

Description: Optical, magnetic, and magneto-optical properties have been investigated for the α-Fe 2 O 3 -doped transparent glasses irradiated with an infrared fs laser and subsequently annealed. The values of the saturation magnetization at room temperature for the irradiated glasses were increased compared with the as-prepared samples, which is due to the precipitation of the ferrimagnetic ferrite nanoparticles (NPs). By adding further dopants as precursors of plasmonic metals, Au or Al NPs were space-selectively precipitated together with the ferrite NPs in a confined region after irradiation and thermal annealing. In the case of the glass codoped with Al, magneto-optical Faraday effect was plasmonically enhanced and exhibited a negative distinct peak ascribed to a coupling between the ferrimagnetism of ferrite NPs and the localized surface plasmon resonance of Al NPs, while the glass, in which ferrite and Au NPs were precipitated, showed a positive enhancement of Faraday effect due to a coupling of plasmon resonance with diamagnetism of glass matrix.

Description: ZnO/MgO core–shell nanorod arrays were synthesized successfully by the hydrothermal growth method. Photoluminescence (PL) emission from the nanorods showed remarkable enhancement after the growth of the MgO layer. The ZnO/MgO core–shell nanorods are type-I heterostructures, the electrons and holes of which are both confined in the core of the nanorods, as a result, leading to the increase of the photoluminescence intensity in this system. In addition, another reason for the enhancement of PL emission was the deposition of MgO shell suppression of surface defects. In addition, the activation energy ( E a ) of 63 meV in the ZnO/MgO core–shell nanorods was obtained from temperature-dependent PL.

Description: Cylindrical vector (CV) partially coherent beam was introduced (Dong et al. Opt Express 19:5979–5992, 2011 ) and generated (Wang et al. Appl Phys Lett 100:051108, 2012 ) recently. In this paper, we derive the realizability conditions for a CV partially coherent beam, and we derive the analytical formula for the cross-spectral density matrix of a CV partially coherent beam propagating in turbulent atmosphere based on the extended Huygens-Fresnel formula. The statistical properties, such as the average intensity, the complex degree of coherence and the degree of polarization of a CV partially coherent beam in turbulent atmosphere are studied in detail and compared with those in free space. It is found that the statistical properties of a CV partially coherent beam in turbulent atmosphere are much different from those in free space, and are affected by the initial beam parameters.

Description: The linewidth of an external cavity quantum cascade laser is studied as a function of injection current and laser scan rate. The laser linewidth is inferred to be ca. 2.5 MHz from Lamb-dip spectra on a low pressure sample of NO and its variation with injection current is well modeled using literature values for the intrinsic material properties of the lasing medium. The laser linewidth measurements are corroborated by polarization spectroscopy studies as well as by analysis of hyperfine structure and cross-over resonances.

Description: Difference frequency generation between broadband visible noncollinear optical parametric amplifier (NOPA) pulses and the fundamental pump laser pulses allows the generation of ultrashort infrared pulses with passively stabilized carrier-envelope phase. A simple prism compressor for the visible NOPA pulses is sufficient to generate few-cycle pulses in the infrared and no additional compression is needed. We theoretically investigate the concept, explain the principles, and demonstrate it for high repetition rate, long pulse durations, and various wavelengths by applying it to a Ti:sapphire and an Yb:KYW-based laser systems. For the latter sub-15 fs phase stable pulses around 1.8 μm with an energy of 100 nJ are obtained at 100 kHz repetition rate.

Description: We study the control of quantum resonances in photonic crystals with electromagnetically induced transparency driven by microwave field. In addition to the control laser, the intensity and phase of the maser can alter the transmission and reflection spectra in interesting ways, producing hyperfine resonances through the combined effects of multiple scattering in the superstructure.

Description: In any field theory the interaction of a wave packet with a multilayered potential is of high theoretical and practical relevance. In the present work we show an extension to any number of layers of the classical Fabry–Perot formula that works for any level of absorption, any thickness of the composing layers, any number of layers, any angle of incidence and for evanescent waves as well. More specifically, the ability of dealing with input evanescent waves and complex metal-based structures is of special interest for superlenses analysis and design. Some explicit examples in electromagnetism are also discussed.

Description: We studied the optical scattering noise, measurement artifacts, and their suppression in single-shot measurements of prepulse contrast. The measurement noise due to air scattering and the two kinds of measurement artifacts resulting from multiple reflections of the generated correlation signal and correlation between the pulse under test and the internally reflected sampling pulse were experimentally explored. The scattering noise and measurement artifacts significantly degrade the measurement fidelity. We demonstrate the clean measurement of prepulse contrast in a single-shot cross-correlator by attenuating the main peak of the correlation beam with a dot mirror and designing the correlating process based on a periodically-poled lithium niobate crystal embedded in an unpoled wafer. The standard time-scanning measurements of pulse contrast are also performed to confirm the experimental results of our single-shot measurement.

Description: Anisole is a promising candidate for use as fluorescent tracer for gas-phase imaging diagnostics. Its high-fluorescence quantum yield (FQY) and its large Stokes shift lead to improved signal intensity (up to 100 times stronger) compared with the often used toluene. Fluorescence spectra and effective fluorescence lifetimes of gaseous anisole were investigated after picosecond laser excitation at 266 nm as a function of temperature (296–977 K) and bath gas composition (varying amounts of N 2 and O 2 ) at total pressures in the range of 1–10 bar to provide spectroscopic data and FQY for applications, e.g., in in-cylinder measurements in internal combustion engines. Fluorescence spectra of anisole extend from roughly 270–360 nm with a peak close to 290 nm at 296 K. The spectra show a red-shift with increasing temperature (0.03 nm/K) and O 2 partial pressure (5 nm from N 2 to air). In the investigated temperature range and in pure N 2 at 1 bar total pressure the effective fluorescence lifetime drops with increasing temperature from 13.3 ± 0.5 to 0.05 ± 0.01 ns. Increasing the total pressure of N 2 leads to a small decrease of the lifetime at temperatures above 400 K (e.g., at 525 K from 4.2 ± 0.2 ns at 1 bar to 2.7 ± 0.2 ns at 10 bar). At constant temperature and in the presence of O 2 the lifetimes decrease significantly (e.g., at 296 K from 13.3 ± 0.5 ns in N 2 to 0.40 ± 0.02 ns in air), with this trend diminishing with increasing temperature (e.g., at 675 K from 1.02 ± 0.08 ns in N 2 to 0.25 ± 0.05 ns in air). A phenomenological model that predicts fluorescence lifetimes, i.e., relative quantum yields as a function of temperature, pressure, and O 2 concentration is presented. The photophysics of anisole is discussed in comparison with other aromatics.

Description: The contribution of the propagating and the evanescent waves associated with freely propagating non-paraxial light fields whose transverse component is azimuthally polarized at some plane is investigated. Analytic expressions are derived for describing both the spatial shape and the relative weight of the propagating and the evanescent components integrated over the transverse plane. The analysis is carried out within the framework of the plane-wave angular spectrum approach. These results are used to illustrate the behavior of a kind of donut-like beams with transverse azimuthal polarization at some plane.

Description: A high-efficiency high-power diode-side-pumped quasi-continuous wave (QCW) Nd:YAG ceramic slab laser using zigzag optical path was demonstrated. With an integrating sphere technique, the scattering and absorption coefficient of the ceramic slab were measured to be 0.0024 and 0.0016 cm −1 at 1,064 nm, respectively. Under a pump power of 6.69 kW, an average output power of 2.44 kW at 1,064 nm with a repetition rate of 400 Hz was achieved, corresponding to an optical-to-optical efficiency of 36.5 %. As far as we know, this is the highest conversion efficiency reported for QCW side-pumped single slab Nd:YAG ceramic laser.

Description: We present a carrier–envelope phase (CEP) stabilized sub-two-cycle 5.2 fs pulse source based on soliton-effect self-compression of femtosecond laser pulses in millimetre-long highly nonlinear photonic crystal fibres. We employ a simple and efficient scheme to generate a strong (40–60 dB, configuration dependent) CEP beat signal directly from the pulse source via f- to-2 f interferometry where the second harmonic of the main soliton pulse is mixed with the isolated dispersive blue/green radiation peak that is also generated in the compression process, obviating the need for additional spectral broadening mechanisms.

Description: The laser behavior and spectral changes occurring in cholesteric liquid crystals with varying dye-doped concentrations were investigated when pumped at 532 nm. It was found that the long-wavelength band edge and the laser line exhibit a blue shift over 21 nm with increasing dye concentration. The circularly polarized fluorescence spectra were examined, and the location of the sense reversion of circular polarization was determined to coincide well with the discrete lasing lines. The blue shift can be ascribed to the decrease in average refractive index and pitch of the dye-doped cholesteric liquid crystals. The dependence of the slope efficiency and threshold energy on the dye concentration can be attributed to the shift in photonic stopband and the change in penetration depth of excitation. The temperature and incident angle of pumping beam also have a significant impact on the lasing properties. The optimal dye concentration is found to be 0.5 wt% at 30.5 °C with an incident angle of 10°. The laser emission located at 601.4 nm with slope efficiency of 4 % was achieved above the threshold energy of 14.3 μJ.

Description: The possibility is studied to develop a straightforward analytical approach to the determination of the optical properties of liquid turbid media having forward-peaked scattering indicatrices. The approach is based on investigating the in-depth behavior of the radius and the axial intensity of a laser radiation beam propagating through the turbid medium. Based on the small-angle approximation, the detected forward-propagating light power spatial distribution, at relatively small or large optical depths along the beam axis, is obtained asymptotically in analytical form allowing one to derive relatively simple expressions of the extinction, reduced-scattering and absorption coefficients and the anisotropy factor of the medium through the characteristics of the propagating light beam. Preliminary experiments have also been performed, using Intralipid dilutions of different relatively low concentrations and measuring the cross-sectional radial distribution of the detected light power at different depths along the beam axis. The corresponding on-axis detected light power profiles have been measured independently as well. The experimental results are consistent with the analytical expressions obtained that allow one to estimate the optical coefficients and the anisotropy factor of the investigated media on the basis of the measured beam characteristics. The values obtained are near those predicted by other researchers.

Description: We propose a scheme to generate stationary quadripartite entanglement in two-mode optical Fabry-Perot cavity, which consisted of the same two fixed mirrors and the same two perfectly reflective movable mirrors. We treat the whole two-cavity fields-two movable mirrors system as intrinsically quadripartite and investigate quadripartite continuous-variable (CV) entanglement among them. Using the criterion proposed by Loock and Furrsawa, we demonstrate that genuine quadripartite CV entanglement can be generated in this system. This system will provide a way to create genuine quadripartite entanglement in a macroscopic level and will hold good prospects for quantum information and quantum networks.

Description: Most photoacoustic (PA) work assumes a point-like detection of generated pressure waves; this assumption results in important differences between predicted and experimental signals, as shown in this paper. We used the geometry of a real sensor in the theoretical signal generation through the discretization of the sensing surface, considering each element as a point-like sensor. We modeled the interaction between the wavefront and the real sensor, starting from a well-known PA pressure relation for a point-like source and punctual detection. We obtained the electrical response of the real sensor experimentally and modeled it as a summation of Gaussian functions. The impulse response was convolved with the total PA pressure to obtain the theoretical PA signal. We analyzed the dependence of the source-sensor distance on the discretization size. Then the predicted signal and experimental data were compared for two different frequency response transducers. We found differences in shape and temporal width of simulated PA signals for point-like-source/punctual-detection model and for point-like-source/finite-sensor model.

Description: The multi-photon ultraviolet upconversion emission properties and synergistic effect are investigated in BaSr 2 Y 6 O 12 :Er 3+ phosphor. The deep-ultraviolet emissions centered at 274, 297 and 324-nm are observed under the 1,540-nm excitation, which results from a seven-, six- and six-photon upconversion process, respectively. A synergistic effect is found, which shows that the red emission intensity under 351- and 1,540-nm dual excitation is 4.7 % time stronger than the sum of red emission intensities under the 351 and 1,540-nm single excitation. This phenomenon is attributed to the 4 I 13/2 and 4 I 11/2 levels of Er 3+ from non-radiative transition process under the 351-nm excitation are excited again to 4 F 9/2 level by absorbing 1,540-nm photon in the 351- and 1,540-nm dual-excitation process.

Description: We present a novel and highly sensitive method to determine the residual angular dispersion of high-power laser pulses after stretching, amplification, and re-compression of the pulses in a chirped-pulse amplification laser system. This method is based on the intentional deflection of a part of the the spectrum within the compressor and aligning the centers of gravity of the two resulting and separated foci with largest possible spectral separation in the far field. Using this technique, we were able to reduce the residual angular dispersion on pulses to less than 0.05 μrad/nm in the vertical plane and less than 0.03 μrad/nm in the horizontal plane, respectively. With this method, it is possible to minimize the deviation of the actual peak intensity for the focused laser pulses to less than 2 % of its theoretical limit.

Description: A novel multipath Mach–Zehnder interferometer (m-MZI) is proposed and experimentally demonstrated, which is fabricated by fusion splicing a segment of all-solid multi-core fiber (MCF) between two sections of single mode fiber-28 with a well-controlled lateral offset at the splice points. Beam propagation method-based simulation results demonstrated light passing throw MCF from multiple paths. Experiments with different lengths of MCF were implemented to investigate our proposed m-MZI’s response to temperature and strain. Compared with previously reported optical fiber modal interferometers, higher phase sensitivity can be obtained in our scheme due to the multipath interference configuration embedded in one fiber. A very high temperature sensitivity of 130.6 pm/°C has been achieved, and the maximum strain sensitivity is less than 0.284 pm/με in all experiments. A record low strain-to-temperature cross-sensitivity of 6.2 × 10 −4  °C/με has been realized, and it shows great significance of this in-fiber integrated multipath Mach–Zehnder interferometer in practical temperature sensing applications.

Description: We propose an experimental scheme to show that the nonlinear magnetic solitary excitations can be achieved in an atomic spinor Bose–Einstein condensate confined in a blue-detuned optical lattice. Through exact theoretical calculations, we find that the magnetic solitons can be generated by the static magnetic dipole–dipole interaction (MDDI), of which the interaction range can be well controlled. We derive the existence conditions of the magnetic solitons under the nearest-neighboring, the next-nearest-neighboring approximations as well as the long-range consideration. It is shown that the long-range feature of the MDDI plays an important role in determining the existence of magnetic solitons in this system. In addition, to facilitate the experimental observation, we apply an external laser field to drive the lattice, and the existence regions for the magnetic soliton induced by the anisotropic light-induced dipole–dipole interaction are also investigated.

Description: Frequently, a certain solution of a nonlinear wave equation is of interest, but no analytic form is known, and one must work with approximations. We introduce a search strategy to find solutions of the propagation of soliton molecules in a dispersion-managed optical fiber and to determine their shape with some precision. The strategy compares shapes before and after propagation and invokes an optimization routine to minimize the difference. The scheme is designed to be implemented in an experiment so that all fiber parameters are taken into account. Here, we present a full numerical study and a verification of convergence; we validate the method with cases of known solutions. We also compare the performance of two optimization procedures, the Nelder–Mead simplex method and a genetic algorithm.

Description: In this work, organic vertical-cavity surface-emitting lasers (VCSELs) with single-mode laser output in the long-wavelength region (~700 nm) of the visible were reported based on the energy transfer between dye pairs consisting of pyrromethene 597 (PM597) and rhodamine 700 (LD700). By co-doping PM597 into the polymeric hosts, the fluorescence intensity of LD700 was enhanced by 30-fold and the photophysical parameters of the donor–acceptor pairs were investigated, indicating the involvement of non-radiative resonance energy transfer processes between PM597 and LD700. Active distributed Bragg reflectors (DBR) were made by alternately spin-coating dye-doped polyvinylcarbazole and cellulose acetate thin films as the high and low refractive index layers, respectively. By sandwiching the active layer with 2 DBR mirrors, VCSEL emission at 698.9 nm in the biological first window (650–950 nm) was observed under the 532-nm laser pulses. The laser slope efficiency and threshold were also measured.

Description: A passively Q-switched Ho:LuAG laser resonantly pumped by a 1.91-μm laser was presented. A comparison analysis of laser performances with two different output couplers was carried out. Using Cr 2+ :ZnS as the saturable absorber, the maximum average output power of 1.14 W was obtained at 2,076.56 nm. The pulse duration was kept constant while increasing the pump power. Meanwhile, the pulse energy is linearly dependent on pump power. The shortest pulse duration of ~36 ns and highest pulse energy of 1.54 mJ were obtained at output coupler transmittance of 25 and 30 %, corresponding to the pulse repetition rate of 554 and 790 Hz, respectively. The beam quality factor of M 2 was 1.05, which is the near diffraction limited.

Description: A high-energy all-solid-state sodium beacon laser at 589 nm with a repetition rate of 50 Hz is introduced, which is based on sum frequency mixing between a 1,064 nm laser and a 1,319 nm laser. The 1,064 nm laser, which features an external modulated CW seed laser and several stages of amplifiers, can provide pulse energy of 740 mJ with ultra-narrow line width (~17 kHz) and superior stability. The 1,319 nm laser can deliver pulse energy of 580 mJ with a narrow line width of 0.6 GHz. By sum frequency mixing in a LBO crystal, pulse energy of 380 mJ is achieved at 589 nm with a conversion efficiency of 29 %. By controlling the center wavelength of 1,064 nm laser, the target beam’s central wavelength is locked to be 589.1592 nm with a line width of 0.6 GHz, which is dominated mainly by the 1,319 nm laser. The beam quality factor is measured to be M 2  = 1.6. The pulse duration is measured to be 140 μs in full-width at half-maximum (FWHM). To the best of our knowledge, this represents the highest pulse energy for all-solid-state sodium beacon laser ever reported.

Description: The performance of an optical sensor that employs an unbuffered polydimethylsiloxane (PDMS)-cladding fiber optic is demonstrated for the sensitive detection of CO 2 gas in the near-infrared region for around 1.57 µm using the apodized 2f/1f wavelength modulation spectroscopy method. The permeability and diffusion characteristics of the PDMS fiber have been theoretically examined and numerically simulated. The results of the simulation are verified by an experimental setup containing a DFB laser source and 5-m-coiled unbuffered PDMS fiber placed in a pre-vacuumed cell filled with about 980 ± 10 Torr of pure CO 2 gas. A minimum detectable absorption of ~0.9 × 10 −4 is measured, corresponding to a detection sensitivity of ~4.5 × 10 −11   \({\text{cm}}^{ - 1} /{\text{Hz}}^{1/2}\) . The effect of the scaling k -factor on the apodized signal is subsequently studied, showing close agreement between the simulation and experimental results.

Description: The mechanism of atomic indium generation for laser-induced fluorescence (LIF) of indium from laser ablation seeding was investigated in a hydrogen/nitrogen non-premixed flame. The morphology and particle size distributions of the ablation products were examined with scanning electron microscopy and transmission electron microscopy. These investigations show that the ablation products comprise complex agglomerates of nano-sized primary particles of indium compounds and micron-sized spherical indium beads. Images of the atomic indium LIF, Mie scattering of ablation products and natural fluorescence emission of indium in the flame were recorded to investigate the mechanism of fluorescence signal generation. The relative contribution of natural fluorescence emission of indium towards the total indium fluorescence signal was assessed by comparing these images. These images also reveal the evolution of ablation products through the flame structure and the correlation between LIF signal and ablation products. It is found that the LIF signal generation is associated with the vapourisation of indium nanoparticles into the gas phase by thermal decomposition in the flame. A further mechanism for thermal decomposition of the nanoparticles was also identified, that of heating the ablation products by in situ laser ablation. This was assessed by means of a second laser, introduced prior to the excitation laser, to reveal that the LIF signal can be enhanced by in situ laser ablation, particularly in the upstream regions of the flame. These findings supersede the mechanism deduced previously by the authors that neutral atomic indium can survive a convection time of the order of tens of seconds and be directly seeded into reacting or non-reacting flows. The possible influences of laser ablation seeding on the nonlinear two-line atomic fluorescence thermometry technique were also assessed.

Description: In this paper, we report on measurements of bremsstrahlung in laser ion acceleration experiments from ultra-thin, polymer-based target foils. The influence of laser polarization on the generated \(\gamma\) radiation, the maximum achievable proton energy and the total proton number is investigated. A clear benefit in terms of \(\gamma\) radiation reduction by the use of circular polarized light can be observed. At the same time, the total number of accelerated protons was increased.

Description: Wavelength modulation spectroscopy combined with signal–reference beam method is used for trace gas detection. The developed technique combines the advantages of common-mode noise suppression and signal-to-noise ratio improvement. The performance of the resulting water vapor sensor is markedly improved because of scanning baseline suppression, effective suppression of the target gas content in the components and resistance to external factors such as temperature and humidity. Trace water vapor detection experiments verify that the measurement accuracy of the system can reach 1 ppmv for an optical path length of 10 cm.

Description: In this paper, we numerically and theoretically investigate the propagation of surface plasmon polaritons in a graphene-based resonator-coupled waveguide system, consisting of a monolayer graphene ribbon coupling to two graphene sheets. The resonance wavelength of this system can be easily tuned by adjusting the chemical potential and the width of the graphene ribbon. Both resonance bandwidth and spectral transmission characteristics of the structure strongly depend on the coupling distance and overlap length between the graphene ribbon and graphene sheets. The structural symmetry is found to be another essential parameter. The presented results may pave the way toward the dynamic control of light propagation in graphene-based structures and the realization of tunable graphene-based optoelectronic devices.

Description:    High-sensitive multi-species detection around 1550 nm using a modulated grating Y-branch, MG-Y, diode laser tunable between 1529 nm and 1565 nm is presented. The MG-Y diode laser is based on the Vernier effect of two modulated gratings, and exhibits quasi-continuous tuning over 36 nm. Multi-species detection is achieved by fast sequential scanning of single absorption lines of CH 4 , CO, C 2 H 2 , and CO 2 distributed over the tuning range of the diode laser. The laser wavelength is scanned about 10 GHz around each absorption line for 5 ms and this is followed by a discrete large jump in operating wavelength to the next line. The MG-Y diode laser has a good repeatability in output frequency between sequential scan segments (〈10 MHz) enabling averaging of the scans. The setup employs digital wavelength modulation spectroscopy, dWMS, with Fourier-based WMS retrieval, applicable through the use of data acquisition cards and coherent sampling. Absorbance sensitivity using 2 f -WMS signals of 7×10 −7 in 30 s (all precisions in this paper are at the 1 σ level) is demonstrated for sensing of four gases and 2×10 −7 when only one gas is detected. Corresponding numbers for 0.5 s of averaging are 4×10 −6 and 1×10 −6 . Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-011-4587-z Authors M. Lewander, National Center for Atmospheric Research, Earth Observing Laboratory, 3450 Mitchell Lane, Boulder, CO 80301, USA A. Fried, National Center for Atmospheric Research, Earth Observing Laboratory, 3450 Mitchell Lane, Boulder, CO 80301, USA P. Weibring, National Center for Atmospheric Research, Earth Observing Laboratory, 3450 Mitchell Lane, Boulder, CO 80301, USA D. Richter, National Center for Atmospheric Research, Earth Observing Laboratory, 3450 Mitchell Lane, Boulder, CO 80301, USA S. Spuler, National Center for Atmospheric Research, Earth Observing Laboratory, 3450 Mitchell Lane, Boulder, CO 80301, USA L. Rippe, National Center for Atmospheric Research, Earth Observing Laboratory, 3450 Mitchell Lane, Boulder, CO 80301, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Using the photonic crystal fiber (PCF) with zero dispersion wavelengths of the fundamental mode and the second-order mode at 985 nm and 885 nm designed and fabricated in our lab, the anti-Stokes signals from 586.5 to 558 nm are efficiently generated in the second-order mode. When the pump working wavelength λ 0 increases from 830 to 880 nm and the input average power P in reduces from 43 to 25 mW, the output power of anti-Stokes signal increases 1.76 times, the power ratio of anti-Stokes signal at 558 nm to the residual pump component at 880 nm is estimated as 5:1, and the maximal conversion efficiency P as / P p 0 can be up to 36%. The possible reasons for the difference from theoretical results are discussed. The combined effects of the interval between the pump working wavelength and zero dispersion wavelength and the input power on the signal conversion process are analyzed. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-011-4581-5 Authors J.-H. Yuan, State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), P.O. Box 163, #, BUPT, 100876 Beijing, China X.-Z. Sang, State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), P.O. Box 163, #, BUPT, 100876 Beijing, China C.-X. Yu, State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), P.O. Box 163, #, BUPT, 100876 Beijing, China X.-J. Xin, State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), P.O. Box 163, #, BUPT, 100876 Beijing, China G.-Y. Zhou, Institute of Infrared Optical Fibers and Sensors, Physics Department, Yanshan University, 066004 Qinhuangdao, China S.-G. Li, Institute of Infrared Optical Fibers and Sensors, Physics Department, Yanshan University, 066004 Qinhuangdao, China L.-T. Hou, Institute of Infrared Optical Fibers and Sensors, Physics Department, Yanshan University, 066004 Qinhuangdao, China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Presently, large efforts are conducted toward the development of highly brilliant γ beams via Compton back scattering of photons from a high-brilliance electron beam, either on the basis of a normal-conducting electron linac or a (super-conducting) Energy Recovery Linac (ERL). Particularly, ERLs provide an extremely brilliant electron beam, thus enabling the generation of highest-quality γ beams. A 2.5 MeV γ beam with an envisaged intensity of 10 15  photons s −1 , as ultimately envisaged for an ERL-based γ -beam facility, narrow band width (10 −3 ), and extremely low emittance (10 −4  mm 2  mrad 2 ) offers the possibility to produce a high-intensity bright polarized positron beam. Pair production in a face-on irradiated W converter foil (200 μm thick, 10 mm long) would lead to the emission of 2×10 13 (fast) positrons per second, which is four orders of magnitude higher compared to strong radioactive 22 Na sources conventionally used in the laboratory. Using a stack of converter foils and subsequent positron moderation, a high-intensity low-energy beam of moderated positrons can be produced. Two different source setups are presented: a high-brightness positron beam with a diameter as low as 0.2 mm, and a high-intensity beam of 3×10 11 moderated positrons per second. Hence, profiting from an improved moderation efficiency, the envisaged positron intensity would exceed that of present high-intensity positron sources by a factor of 100. Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-011-4594-0 Authors C. Hugenschmidt, FRM II and Physik Department E21, Technische Universität München, 85747 Garching, Germany K. Schreckenbach, FRM II and Physik Department E21, Technische Universität München, 85747 Garching, Germany D. Habs, Fakultät für Physik, Ludwig-Maximilians Universität, 85748 Garching, Germany P. G. Thirolf, Fakultät für Physik, Ludwig-Maximilians Universität, 85748 Garching, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The photoluminescence (PL) of LiTb(PO 3 ) 4 , LiGd 0.97 Sm 0.03 (PO 3 ) 4 , and LiTb 0.97 Sm 0.03 (PO 3 ) 4 under vacuum ultraviolet (VUV)/ultraviolet (UV) excitation were studied. We observed the VUV–UV sensitization of Sm 3+ emission (561 nm, 601 nm, 649 nm, and 710 nm) by Tb 3+ in LiTb(PO 3 ) 4 :Sm 3+ , which leads to the yellow light emission (486 nm, 546 nm, 561 nm, 587 nm, 601 nm, 621 nm, 649 nm, and 710 nm) of LiTb(PO 3 ) 4 :Sm 3+ phosphor under UV and VUV excitation. The emission is a result of partial energy transfer from Tb 3+ to Sm 3+ , which is discussed in detail in terms of the excitation and emission spectra and decay curves. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-011-4580-6 Authors B. Han, KLGHEI of Environment and Energy Chemistry, MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China H. Liang, KLGHEI of Environment and Energy Chemistry, MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China Y. Huang, Beijing Synchrotron Radiation Facilities, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100039 People’s Republic of China Y. Tao, Beijing Synchrotron Radiation Facilities, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100039 People’s Republic of China Q. Su, KLGHEI of Environment and Energy Chemistry, MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Tricalcium aluminate doped with Eu 3+ was prepared at furnace temperatures as low as 500°C by using the convenient combustion route and examined using powder X-ray diffraction, scanning electron microscope and photoluminescence techniques. A room-temperature photoluminescence study showed that the phosphors can be efficiently excited by UV/Visible region, emitting a red light with a peak wavelength of 616 nm corresponding to the 5 D 0 – 7 F 2 transition of Eu 3+ ions. The phosphor exhibits three thermoluminescence (TL) peaks at 195°C, 325°C and 390°C. Electron Spin Resonance (ESR) studies were carried out to study the defect centres induced in the phosphor by gamma irradiation and also to identify the defect centres responsible for the TL process. Room-temperature ESR spectrum of irradiated phosphor appears to be a superposition of three distinct centres. One of the centres (centre I) with principal g-value 2.0130 is identified as O − ion while centre II with an axially symmetric principal values g ∥ =2.0030 and g ⊥ =2.0072 is assigned to an F + centre (singly ionized oxygen vacancy). O − ion (hole centre) correlates with the TL peak at 195°C and the F + centre (electron centre), which acts as a recombination centre, is also correlated to the 195°C TL peak. F + centre further appears to be related to the high temperature peak at 390°C. Centre III is also assigned to an F + centre and seems to be the recombination centre for the TL peak at 325°C. Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-011-4589-x Authors V. Singh, Department of Chemistry, Kyungpook National University, Daegu, 702701 Republic of Korea S. Watanabe, Institute of Physics, University of Sao Paulo, 05508-090 Sao Paulo, SP, Brazil T. K. Gundu Rao, Institute of Physics, University of Sao Paulo, 05508-090 Sao Paulo, SP, Brazil I.-J. Lee, Department of Chemistry, Dongguk University, 707 Suckjang-dong, Gyeongju-Si, Gyeongbuk, 780-714 Korea Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Nonlinear electron emission processes induced by surface plasmon oscillations have been studied both experimentally and theoretically. The measured above-threshold electron spectra extend up to high energies whose appearance cannot be explained solely by standard non-perturbative methods, which predict photon energy separated discrete energy line spectra with the known fast fall–plateau–cutoff envelope shape, even when taking the large field enhancement into account. The theoretical analysis of our data, based on the concept of plasmon-induced surface near-field effects, gives a reasonably good explanation and qualitative agreement in the whole intensity range. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-011-4582-4 Authors S. Varró, Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, 1525 Budapest, Hungary N. Kroó, Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, 1525 Budapest, Hungary Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    In this study, optical bistability accompanied by spatial hysteresis was demonstrated in an Nd:GdVO 4 laser with an intracavity twisted-nematic liquid crystal. The low branch of power hysteresis mainly has the spatial distribution of the fundamental mode as the pump power increases, whereas a four-mode and varying transverse pattern exist in the high branch of power hysteresis as the pump power decreases. The result revealed that the power and spatial hysteresis is controlled by the director axis reorientation and the order parameter modification in twisted-nematic liquid crystals, which is determined by the non-uniform transverse distribution of the intracavity laser intensity. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-011-4590-4 Authors M.-D. Wei, Department of Electro-Optical Engineering, National Cheng Kung University, No. 1, University Road, Tainan City, 701 Taiwan, R.O.C. D.-Y. Huang, Department of Photonics, Feng Chia University, 100 Wenhwa Rd., Seatwen, Taichung, 407 Taiwan, R.O.C. C.-C. Hsu, Department of Electro-Optical Engineering, National Cheng Kung University, No. 1, University Road, Tainan City, 701 Taiwan, R.O.C. A.-K. Chang, Department of Photonics, Feng Chia University, 100 Wenhwa Rd., Seatwen, Taichung, 407 Taiwan, R.O.C. J.-H. Lin, Department of Electro-Optical Engineering & In Institute of Electro-Optical Engineering, National Taipei University of Technology, Taipei, 10608 Taiwan, R.O.C. Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A novel technique is represented that allows one to measure vibrations from a distant object with micron and sub-micron amplitudes in real time. The method is based on the speckle interference phenomena and speckle pattern analysis. The scheme allows us to use a single photodiode as a photo-detector and to obtain information from an analog signal without any additional post-processing, which significantly simplifies the device realization compared with the available today laser vibrometers based both on interferometric and on speckle pattern analysis principles. The scheme investigated was implemented as a device and several studies of the practical applications were carried out. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-011-4585-1 Authors A. A. Veber, General Physics Institute, GSP-1, Vavilov str., 38, Moscow, 119991 Russia A. Lyashedko, General Physics Institute, GSP-1, Vavilov str., 38, Moscow, 119991 Russia E. Sholokhov, General Physics Institute, GSP-1, Vavilov str., 38, Moscow, 119991 Russia A. Trikshev, General Physics Institute, GSP-1, Vavilov str., 38, Moscow, 119991 Russia A. Kurkov, General Physics Institute, GSP-1, Vavilov str., 38, Moscow, 119991 Russia Y. Pyrkov, General Physics Institute, GSP-1, Vavilov str., 38, Moscow, 119991 Russia A. E. Veber, General Physics Institute, GSP-1, Vavilov str., 38, Moscow, 119991 Russia V. Seregin, General Physics Institute, GSP-1, Vavilov str., 38, Moscow, 119991 Russia V. Tsvetkov, General Physics Institute, GSP-1, Vavilov str., 38, Moscow, 119991 Russia Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    An ultrahigh contrast laser pulse of over 10 11 for 6 ps before the main pulse was achieved by employing a double plasma mirror installed at the end of a 100 TW Ti:sapphire laser system. Spatial beam qualities such as focusability and stability were found to be extremely sensitive in the range of 14–360 J/cm 2 on the double plasma mirror, while ultrahigh contrast was maintained. At the fluence of 90 J/cm 2 the focusability of the ultrahigh contrast laser was not degraded, and the stability was very close to that obtained without the double plasma mirror when the 2-dimensional normalized standard deviation and the correlation function for several laser beam profiles were analyzed. These results are requisites for carrying out relativistic laser-plasma interactions with ultrahigh contrast laser pulses, enabling the use of ultrathin solid targets. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-011-4584-2 Authors IJ. Kim, Center for Femto-Atto Science and Technology, Advanced Photonics Research Institute, GIST, Gwangju, 500-712 Korea I. W. Choi, Center for Femto-Atto Science and Technology, Advanced Photonics Research Institute, GIST, Gwangju, 500-712 Korea S. K. Lee, Center for Femto-Atto Science and Technology, Advanced Photonics Research Institute, GIST, Gwangju, 500-712 Korea K. A. Janulewicz, Center for Femto-Atto Science and Technology, Advanced Photonics Research Institute, GIST, Gwangju, 500-712 Korea J. H. Sung, Center for Femto-Atto Science and Technology, Advanced Photonics Research Institute, GIST, Gwangju, 500-712 Korea T. J. Yu, Center for Femto-Atto Science and Technology, Advanced Photonics Research Institute, GIST, Gwangju, 500-712 Korea H. T. Kim, Center for Femto-Atto Science and Technology, Advanced Photonics Research Institute, GIST, Gwangju, 500-712 Korea H. Yun, Department of Physics, KAIST, Yuseong-gu, Daejeon, 305-701 Korea T. M. Jeong, Center for Femto-Atto Science and Technology, Advanced Photonics Research Institute, GIST, Gwangju, 500-712 Korea J. Lee, Center for Femto-Atto Science and Technology, Advanced Photonics Research Institute, GIST, Gwangju, 500-712 Korea Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We describe a high-energy, frequency chirped laser system designed for optical Stark deceleration of cold molecules. This system produces two, pulse amplified beams of up to 700 mJ with flat-top temporal profiles, whose frequency and intensity can be well controlled for durations from 20 ns–10 μs. The two beams are created by amplifying a single, rapidly tunable Nd:YVO 4 microchip type laser at 1064 nm, which can be frequency chirped by up to 1 GHz over the duration of the pulse. Intensity modulation induced by relaxation oscillations in the microchip laser during the frequency chirp are virtually eliminated by injection locking a free running semiconductor diode laser before pulsed amplification. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-011-4599-8 Authors N. Coppendale, University College London, Gower Street, London, WC1E 6BT UK L. Wang, University College London, Gower Street, London, WC1E 6BT UK P. Douglas, University College London, Gower Street, London, WC1E 6BT UK P. F. Barker, University College London, Gower Street, London, WC1E 6BT UK Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The Li-rich vapor transport equilibration (VTE) effect on surface refractive index of MgO (5 mol%)-doped LiNbO 3 crystal is studied at the wavelengths of 473, 632.8 and 1536 nm. The results show that in the early stage of VTE the ordinary index n o decreases substantially with the VTE duration t , then recovers slightly, and tends to a constant for t 〉80 h. The extraordinary index n e shows a similar VTE effect but reveals a relatively weak dependence on the VTE duration. Secondary ion mass spectrometry analysis shows that the VTE induces Mg diffusion within the crystal and hence an inhomogeneous Mg depth profile, depending on the VTE duration. As the VTE is prolonged the Mg homogeneity is improved. The surface Mg concentration, determined from the measured surface n o and energy dispersive X-ray analysis, shows a substantial VTE duration dependence, which is responsible for the substantial VTE effect on surface index. Neutron activation analysis shows that the VTE hardly induces the MgO loss from the crystal. It appears that the Mg ions counter diffuse to the crystal surface in the early stage of VTE and then diffuse slowly back into the bulk of the crystal toward equilibrium as Li concentration tends to equilibrium. Gravimetric measurement shows that the Li 2 O content in the crystal increases with the VTE duration in the early stage of VTE and saturates for t 〉60 h, and the Li 2 O content increase in the saturation regime is about 2.25 mol%. Content Type Journal Article Pages 1-10 DOI 10.1007/s00340-011-4601-5 Authors D.-L. Zhang, Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin, 300072 China B. Chen, Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin, 300072 China L. Qi, Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin, 300072 China P.-R. Hua, Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin, 300072 China Y.-M. Cui, Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin, 300072 China D.-Y. Yu, Department of Opto-electronics and Information Engineering, School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin, 300072 China E. Y.-B. Pun, Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A planar five-layer waveguide with a metal-insulator (with the low permittivity)-metal structure embedded in a high-permittivity dielectric is theoretically studied. A long-range surface mode draws special attention because of its superior properties of low attenuation and a large field localized inside the nanoscale middle gap provided with permittivity-contrast. Effects of the surrounding permittivity and the metal film thickness are investigated, and the electric field amplitude in the gap can be dozens of times higher than that at the outer interfaces. This plasmonic structure may have potential applications in integrated photonic devices. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-011-4604-2 Authors L. Wang, State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing, 100871 China Y. Gu, State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing, 100871 China X. Hu, State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing, 100871 China Q. Gong, State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing, 100871 China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A novel sol-gel/laser-induced technique (SGLIT) has been developed to form nanocrystalline titanium dioxide (TiO 2 ) based thin films with an improved antibacterial performance. TiO 2 precursor films loaded with W +6 and Ag +2 ions (W–TiO 2 , Ag–TiO 2 ) were prepared separately by sol-gel method and spin-coated on microscopic glass slides. As-dried films were subjected to KrF excimer laser pulses at optimized parameters to generate mesoporous anatase and rutile phases at room temperature. The anatase phase was obtained after irradiation with 10 laser pulses only at 75–85 mJ/cm 2 fluence in W–TiO 2 films. However, higher number of laser pulses and higher W +6 content favored the formation of rutile. Whereas Ag–TiO 2 films exhibited anatase up to 200 laser pulses at the same fluence. The films were characterized by using XRD, FEG-SEM, TEM and UV-Vis spectrophotometer to investigate the crystallographic structure, phase transformation, surface morphology, film thickness and the optical properties. A crystallite size of approximately 20 nm was achieved from the anatase prepared by SGLIT. The films exhibited an enhanced antibacterial function against E-Coli cells under the UV excitation. Content Type Journal Article Pages 1-12 DOI 10.1007/s00340-011-4600-6 Authors Y. F. Joya, Corrosion and Protection Centre, The Mill, School of Materials, The University of Manchester, Manchester, M13 9PL UK Z. Liu, Corrosion and Protection Centre, The Mill, School of Materials, The University of Manchester, Manchester, M13 9PL UK T. Wang, School of Biomedicine, Faculty of Medical and Human Sciences, The 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:    Iron oxide films were deposited on 〈100〉 Si substrates by reactive pulsed laser deposition (RPLD) using a KrF laser (248 nm). These films were deposited too by laser (light) chemical vapor deposition (LCVD) using continuous ultraviolet photodiode radiation (360 nm). The deposited films demonstrated semiconducting properties. These films had large thermo-electromotive force (e.m.f.) coefficient ( S ) and high photosensitivity ( F ). For films deposited by RPLD the S coefficient varied in the range 0.8–1.65 mV/K at 205–322 K. This coefficient depended on the band gap ( E g ) of the semiconductor films, which varied in the range 0.43–0.93 eV. The largest F value found was 44 V c /W for white light at power density I ≅0.006 W/cm 2 . Using LCVD, iron oxide films were deposited from iron carbonyl vapor. For these films, the S coefficient varied in the range −0.5 to 1.5 mV/K at 110–330 K. The S coefficient depended on E g of the semiconductor films, which varied in the range 0.44–0.51 eV. The largest F value of these films was about 40 V c /W at the same I ≅0.006 W/cm 2 . Our results showed that RPLD and LCVD can be used to synthesize iron oxide thin films with variable stoichiometry and, consequently, with different values of E g . These films have large S coefficient and high photosensitivity F and therefore can be used as multi-parameter sensors: thermo–photo sensors. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-011-4598-9 Authors S. A. Mulenko, Institute for Metal Physics, NAS of Ukraine, 36, Academician Vernadsky Blvd., 03142 Kiev 142, Ukraine N. T. Gorbachuk, Kiev State University of Technology and Design, 03011 Kiev 11, Ukraine Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A special technique is developed to measure the 13 CO 2 / 12 CO 2 isotope ratio in human breath at atmospheric pressure with a 2 μm tunable diode laser. The procedure used to process the pressure-broadened spectra obtained and calculating the isotope ratio is based on a multidimensional linear regression of the spectra using simulated 13 CO 2 , 12 CO 2 , and H 2 O spectra. This technique allows the measurement of the δ -value for isotopic ratios with a precision of 0.07‰ within a data acquisition time of 3 min and a long-term reproducibility of 0.2‰. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-011-4602-4 Authors S. N. Andreev, P.N. Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prosp. 53, Moscow, 119991 Russia E. S. Mironchuk, P.N. Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prosp. 53, Moscow, 119991 Russia I. V. Nikolaev, P.N. Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prosp. 53, Moscow, 119991 Russia V. N. Ochkin, P.N. Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prosp. 53, Moscow, 119991 Russia M. V. Spiridonov, P.N. Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prosp. 53, Moscow, 119991 Russia S. N. Tskhai, P.N. Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prosp. 53, Moscow, 119991 Russia Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The transition between the two Zeeman sublevels of 2 S 1/2 in a single trapped 40 Ca + ion is directly excited by a radio-frequency magnetic field. A coherence time of 29.4±2.5 ms is measured by Ramsey interferometry. The ratio of the maximum Rabi frequency of the Zeeman transition (∼250 kHz) to the inverse of the coherence time is 7.3×10 3 , which is considered to be a figure of merit for Zeeman states when they are used as a quantum bit. Several applications of the Zeeman qubit to quantum information processing are also discussed. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-011-4603-3 Authors S. Haze, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan T. Ohno, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan K. Toyoda, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan S. Urabe, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We describe a novel method to improve the temporal intensity contrast (TIC) between the main pulse and prepulses in a high-power chirped-pulse amplification (CPA) laser system. Pre- and post-pulses originating from the limited extinction ratio of the polarization gating equipment are suppressed by carefully adjusting the round-trip times of the regenerative amplifiers (RAs) with respect to the oscillator. As a result, leaking pulses from earlier or later round-trips in the RAs are hidden below the temporal shape of the main pulse. The synchronization can easily be controlled by a contrast measurement on a picosecond time scale using a third-order cross-correlator that enables a sub-mm precise adjustment of the cavity lengths. Finally, a method based on spectral interference is introduced that can be used for a fine-adjustment of the cavity lengths for the daily operation, making this new method easy to implement into existing laser systems. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-011-4633-x Authors S. Keppler, Institute of Optics and Quantum Electronics, FSU Jena, Max-Wien-Platz 1, 07743 Jena, Germany R. Bödefeld, Institute of Optics and Quantum Electronics, FSU Jena, Max-Wien-Platz 1, 07743 Jena, Germany M. Hornung, Institute of Optics and Quantum Electronics, FSU Jena, Max-Wien-Platz 1, 07743 Jena, Germany A. Sävert, Institute of Optics and Quantum Electronics, FSU Jena, Max-Wien-Platz 1, 07743 Jena, Germany J. Hein, Institute of Optics and Quantum Electronics, FSU Jena, Max-Wien-Platz 1, 07743 Jena, Germany M. C. Kaluza, Institute of Optics and Quantum Electronics, FSU Jena, Max-Wien-Platz 1, 07743 Jena, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We fabricated a highly efficient, broadband light emitting diode driven by an optical near field generated at the inhomogeneous domain boundary of a dopant in a homojunction bulk Si crystal and evaluated its performance. To fabricate this device, a forward current was made to flow through a Si p–n junction to anneal it. During this process, the device was irradiated with near-infrared light, producing stimulated-emission light using a two-step phonon-assisted process triggered by the optical near field, and the annealing rate was controlled in a self-organized manner. The device emitted light in a wide photon energy region of 0.73–1.24 eV (wavelength 1.00–1.70 μm). The total power of the emitted light with 11 W of electrical input power was as high as 1.1 W. The external power conversion efficiency of the emitted light was 1.3%, the differential external power conversion efficiency was 5.0%, the external quantum efficiency was 15%, and the differential external quantum efficiency was 40%. The dependency of the emitted light power density on the injected current density clearly showed a characteristic reflecting the two-step phonon-assisted transition process. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-011-4596-y Authors T. Kawazoe, Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan M. A. Mueed, Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan M. Ohtsu, Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We describe an algorithm for using a confocal microscope for tracking single fluorescent particles diffusing in three dimensions. The algorithm uses a standard confocal setup and directly translates each fluorescence measurement into an actuator command. Through physical simulations, we illustrate 3-D tracking in both stage scanning and beam scanning confocal systems. The simulated stage scanning system achieved tracking of particles diffusing in 3-D with coefficients up to 0.2 μm 2 /s when the average fluorescence intensities was less than 1.84 counts per measurement cycle (corresponding to less than 18,400 counts per second) in the presence of background fluorescence with a rate of 5,000 counts per second. Increasing the fluorescence intensity to approximately 193 counts per measurement cycle (1,930,000 counts per second) allowed the system to track up to particles diffusing with coefficients as large as 0.7 μm 2 /s. The beam steering system allowed for faster motion of the focal volume of the microscope and successfully tracked particles diffusing with coefficients up to 0.7 μm 2 /s with fluorescence measurement intensities of approximately 0.189 counts per measurement cycle (37,570 counts per second) and with coefficients up to 90 μm 2 /s when the fluorescence intensity was increased to 19 counts per measurement cycle (3,807,500 counts/sec). Content Type Journal Article Pages 1-13 DOI 10.1007/s00340-011-4514-3 Authors S. B. Andersson, Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Propagation of a linearly polarized partially coherent dark hollow beam (DHB) through a high numerical aperture (NA) thin lens is formulated. The tight focusing properties, such as the degree of polarization, the intensity distribution, and the degree of coherence, of a partially coherent DHB are investigated in detail. It is found that the focusing properties of a partially coherent DHB are closely determined by the initial coherence, beam order, and the NA of the thin lens. Content Type Journal Article Pages 1-10 DOI 10.1007/s00340-011-4517-0 Authors Y. Dong, Department of Physics, Shaoxing University, Shaoxing, 312000 China Y. Cai, School of Physical Science and Technology, Soochow University, Suzhou, 215006 China C. Zhao, 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:    The results of a novel technique for the quantification of oxygen in an isothermal turbulent free jet using toluene laser induced fluorescence (LIF) are presented. This method relies on the red-shift of the toluene LIF emission spectrum with increasing oxygen concentration. Evaluating the LIF signal ratio from two different wavelength regions simultaneously produces results that depend only on the local oxygen concentration. From calibration data, obtained from repeated tests, the oxygen sensitivity of the two-color LIF technique is best for oxygen partial pressures in the current setup. Quantified images of oxygen distribution are presented for 40.4, 60.5, 80.5, and 103 mbar in the toluene-seeded jet flow that is shielded by a toluene-seeded nitrogen co-flow at atmospheric pressure and temperature. Based on the average oxygen concentration images (obtained from 100 instantaneous oxygen images), the error in accuracy of measuring the oxygen concentration was 0.8, 3.0, 7.7, and 7.3% with a precision of ± 8.6, 5.5, 13.3, and 11.6% for the jet cases, respectively. The main jet flow characteristics have been captured by the technique as determined from the measured oxygen distribution images. Centerline profiles of average oxygen concentration, normalized to the value at the nozzle exit, demonstrate self-similar behavior from 5 mm above the nozzle exit. Radial oxygen concentration profiles exhibit a Gaussian-type distribution that broadens with distance above the nozzle exit, in agreement with literature. Content Type Journal Article Pages 1-9 DOI 10.1007/s00340-011-4564-6 Authors K. Mohri, IVG, University of Duisburg-Essen, Duisburg, Germany M. Luong, IVG, University of Duisburg-Essen, Duisburg, Germany G. Vanhove, PC2A, UMR 8522 CNRS Universite de Lille 1, Villeneuve d’Ascq, France T. Dreier, IVG, University of Duisburg-Essen, Duisburg, Germany C. Schulz, IVG, University of Duisburg-Essen, Duisburg, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We report a prototype CO 2 gas sensor based on a simple blackbody infrared source and a spectrally narrow quantum cascade detector (QCD). The detector absorption spectrum is centered at 2260 cm −1 (4.4 μm) and has a full width at half maximum of 200 cm −1 (25 meV). It covers strong absorption bands of two spectrally overlapping CO 2 isotopomers, namely the P-branch of 12 CO 2 and the R-branch of 13 CO 2 . Acquisition of the spectral information and data treatment were performed in a Fourier transform infrared (FTIR) spectrometer. By flushing its sample compartment either with nitrogen, dry fresh air, ambient air, or human breath, we were able to determine CO 2 concentrations corresponding to the different gas mixtures. A detection limit of 500 ppb was obtained in these experiments. Content Type Journal Article Pages 1-4 DOI 10.1007/s00340-011-4532-1 Authors D. Hofstetter, Institute of Physics, University of Neuchâtel, 51 Avenue de Bellevaux, 2009 Neuchâtel, Switzerland J. Di Francesco, Institute of Physics, University of Neuchâtel, 51 Avenue de Bellevaux, 2009 Neuchâtel, Switzerland L. Hvozdara, Optics and Photonics Technology Laboratory, Institute of Microtechnology, EPFL, A.-L. Breguet 2, 2000 Neuchâtel, Switzerland H.-P. Herzig, Optics and Photonics Technology Laboratory, Institute of Microtechnology, EPFL, A.-L. Breguet 2, 2000 Neuchâtel, Switzerland M. Beck, Quantum Optoelectronics Group, Institute of Quantum Electronics, ETHZ, Wolfgang-Pauli-Strasse 16, 8093 Zurich, Switzerland Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A high-energy Q-switched Er:YAG laser in-band pumped by an Er,Yb co-doped fiber laser is reported. A simple two-mirror multi-mode resonator incorporating an electro-optic Q-switch and a multi-Brewster-plate polarizer was employed, together with a simple compensation scheme to reduce the depolarization loss due to thermally induced stress birefringence in the Er:YAG crystal at high pump powers. The laser yielded Q-switched pulses at 1617 nm with 30.5-mJ pulse energy and 〈20-ns pulse duration (FWHM) at 20-Hz repetition rate, corresponding to a peak power of 〉1.5 MW for 55 W of pump power at 1532 nm. The prospects for further improvement in Q-switched performance are discussed. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-011-4542-z Authors J. W. Kim, Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ UK J. K. Sahu, Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ UK W. A. Clarkson, Optoelectronics Research Centre, University of Southampton, Southampton, SO17 1BJ UK Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description: In this paper, we present a modified version of the Mach–Zehnder interferometer. An arrangement of two linear polarizers and a wave rotator has been inserted in the light’s path. Using this new arrangement, we are able to obtain a double image of a birefringent fibre. This double image records the shifts of the Mach–Zehnder’s fringes for the light vibrating parallel and perpendicular to the fibre’s axis in the same image. Moreover, by controlling the beam splitters, we are able to get an overlap between two images of the fibre and to directly observe an image describing the birefringence of the investigated fibre. This new arrangement has been applied to three polypropylene fibres and a graded-index FOS optical fibre in order to demonstrate its validity and powerful ability for monitoring the direct birefringence. A set of images of the investigated samples is presented and compared with images obtained using the classical Mach–Zehnder interferometer.

Description: We report on simultaneous efficiency and divergence measurements for harmonics from solid targets generated by the relativistic oscillating mirror mechanism. For a value of the normalized vector potential of \(a_{\mathrm{L}}\simeq 1.5\) , we demonstrate the generation of 30 μJ high-harmonic radiation in a \(17\pm 3\) mrad divergence cone. This corresponds to a conversion efficiency of \(\gtrsim\) 10 −4 in the 17–80 nm range into a well-confined beam. Presuming phase-locked harmonics, our results predict unprecedented levels of average power for a single attosecond pulse in the generated pulse train. Results of PIC simulations raise the prospect of attaining efficiencies of a few percent at higher laser intensities.

Description: A wineglass has been used as an acoustic resonator to enhance the photoacoustic signal generated by laser excitation of absorbing dyes in solution. The amplitude of the acoustic signal was recorded using a fiber-optic transducer based on a Fabry–Pérot cavity attached to the rim of the wineglass. The optical and acoustic properties of the setup were characterized, and it was used to quantify the concentration of phosphomolybdenum blue and methyl red solutions. Detection limits of 1.2 ppm and 8 μM were obtained, respectively.

Description: In this manuscript, we present the first quantitative multi-scalar measurements by time-domain-based supercontinuum absorption spectroscopy in a flame. Temperature and \(\hbox {H}_{2}\hbox {O}\) mole fraction are determined simultaneously from broadband \(\hbox {H}_{2}\hbox {O}\) spectra ranging from 1,340 to 1,485 nm by a multi-peak least square fit between experiments and simulated spectra. To this end, a combination of the most comprehensive databases, namely the Barber–Tennyson database (BT2) and HITRAN2012, is used. Line strength values listed in BT2 are combined with averaged broadening coefficients and temperature exponents based on the upper rotational quantum number J from the latest HITRAN database to precisely model the line shape function for each transition. The height-dependent temperature and \(\hbox {H}_{2}\hbox {O}\) mole fraction profiles of a premixed one-dimensional flame of a McKenna type burner are reconstructed by direct comparison of experimental spectra with theory. For verification, the temperature data obtained are compared with a profile determined by coherent anti-Stokes Raman scattering.

Description:    New transverse orthogonal axes associated with the beam shape are introduced on the basis of the irradiance-moment formalism that describes the overall spatial structure of partially coherent paraxial beams. We refer to them as the intrinsic axes of the beam. The angle between these axes and the laboratory reference coordinates can be determined from the measurements of the second-order spatial moments of the beam, even although the field amplitude is not analytically known. It has been found that the intrinsic axes remain invariant upon propagation through rotationally symmetric first-order optical systems. Two additional analytical quantities have also been introduced. One of them provides a measure of the beam symmetry, and the other one contains information about the beam rotation under propagation. When the field is referred to the intrinsic axes, these two quantities are shown to reach their extreme values. The results are illustrated by means of an example. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-011-4661-6 Authors R. Martínez-Herrero, Departamento de Óptica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain P. M. Mejías, Departamento de Óptica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain M. Larraona-Puy, Departamento de Óptica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain A. Manjavacas, Instituto de Óptica, CSIC, Serrano 121, 28006 Madrid, Spain Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description: Selected papers in nonlinear dynamics in dissipative and discrete optical systems Content Type Journal Article Pages 1-2 DOI 10.1007/s00340-011-4677-y Authors F. Lederer, Institute of Condensed Matter Theory and Solid State Optics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany S. Nolte, Institute of Applied Physics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany A. Tünnermann, Institute of Applied Physics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Mixture fraction measurements in a jet-in-cross flow configuration at high pressures (15 bar) and temperatures (above 1000 K) were performed using planar laser induced fluorescence of nitric oxide (NO-PLIF) as trace species. The goal was the evaluation of this tracer LIF technique for the characterization of the mixing of fuel and hot exhaust gas in the mixing channel. The fuel (natural gas (NG) or H 2 /N 2 /NG mixture) along with the tracer were injected into the crossflow of the exhaust gas and PLIF measurements were performed in different planes. In order to relate the measured NO-LIF signal to fuel concentration and mixture fraction, effects of pressure, temperature and species concentration were taken into account. Numerical calculations and spectroscopic simulations that mimic the experimental conditions were performed to identify excitation schemes that give optimum correlations between the NO-LIF signal and the mixture fraction. The measured NO-PLIF images were transformed into mixture fraction plots using the computed correlations. The paper reports on the experimental challenges encountered during the measurements and the steps taken to overcome those difficulties. Examples of mixture fraction distributions are presented and discussed. The paper concludes with a detailed analysis on the accuracy of the measured mixture fraction values. Content Type Journal Article Pages 1-12 DOI 10.1007/s00340-011-4655-4 Authors R. Sadanandan, Institut für Verbrennungstechnik, Deutsches Zentrum für Luft- und Raumfahrt e.V., Pfaffenwaldring 38-40, 70569 Stuttgart, Germany J. Fleck, Institut für Verbrennungstechnik, Deutsches Zentrum für Luft- und Raumfahrt e.V., Pfaffenwaldring 38-40, 70569 Stuttgart, Germany W. Meier, Institut für Verbrennungstechnik, Deutsches Zentrum für Luft- und Raumfahrt e.V., Pfaffenwaldring 38-40, 70569 Stuttgart, Germany P. Griebel, Institut für Verbrennungstechnik, Deutsches Zentrum für Luft- und Raumfahrt e.V., Pfaffenwaldring 38-40, 70569 Stuttgart, Germany C. Naumann, Institut für Verbrennungstechnik, Deutsches Zentrum für Luft- und Raumfahrt e.V., Pfaffenwaldring 38-40, 70569 Stuttgart, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We present the setup and test of a transportable clock laser at 698 nm for a strontium lattice clock. A master-slave diode laser system is stabilized to a rigidly mounted optical reference cavity. The setup was transported by truck over 400 km from Braunschweig to Düsseldorf, where the cavity-stabilized laser was compared to a stationary clock laser for the interrogation of ytterbium (578 nm). Only minor realignments were necessary after the transport. The lasers were compared using a Ti:Sapphire frequency comb as a transfer oscillator. The generated virtual beat showed a combined linewidth below 1 Hz (at 1156 nm). The transport back to Braunschweig did not degrade the laser performance, as was shown by interrogating the strontium clock transition. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-011-4652-7 Authors S. Vogt, Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany C. Lisdat, Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany T. Legero, Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany U. Sterr, Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany I. Ernsting, Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany A. Nevsky, Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany S. Schiller, Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We extend the concept of cross-spectral purity from the spectral density to the polarization properties of electromagnetic fields by considering the polarization Stokes parameters. We show that purity conditions similar to those in the case of electromagnetic cross-spectral purity can be derived for all the Stokes parameters. Furthermore, we introduce a situation of strict cross-spectral purity which leads to the equality of the degrees of coherence for electromagnetic fields in the space–time and space–frequency domains. Content Type Journal Article Pages 1-4 DOI 10.1007/s00340-011-4668-z Authors T. Hassinen, Department of Physics and Mathematics, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland J. Tervo, Department of Physics and Mathematics, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland A. T. Friberg, Department of Physics and Mathematics, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    A new method for efficient, broadband sum and difference frequency generation of ultrafast pulses is demonstrated. The principles of the method follow from an analogy between frequency conversion and coherent optical excitation of a two-level system. For conversion of ultrafast pulses, the concepts of adiabatic conversion are developed further in order to account for dispersion and group velocity mismatch. The scheme was implemented using aperiodically poled nonlinear crystals and a single step nonlinear mixing process, leading to conversion of near-IR (∼790 nm) ultrafast pulses into the blue (∼450 nm) and mid-IR (∼3.15 μm) spectral regions. Conversion bandwidths up to 15 THz FWHM and efficiencies up to 50% are reported. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-011-4591-3 Authors H. Suchowski, Deptartment of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, 76100 Israel B. D. Bruner, Deptartment of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, 76100 Israel A. Ganany-Padowicz, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978 Israel I. Juwiler, Dept. of Electrical and Electronics Engineering, Sami Shamoon College of Engineering, Ashdod, 77245 Israel A. Arie, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978 Israel Y. Silberberg, Deptartment of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, 76100 Israel Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We present that a focus of terahertz radiation can be tailored based on coherent scattering of surface plasmon polaritons (SPPs) from a partially defected metal corrugation based on numerical simulations. The introduction of teeth defects in the corrugation allows coupling of the guided SPPs with the radiation and the far-field behavior is tailored by the spatial arrangement of such defects. The proposed structures serve as a kind of planar lenses which are quite thin and inexpensive. Promising applications include interfacing lens antennas between terahertz plasmonic integrated circuits and the external free space, which make terahertz systems very compact and low-cost. Content Type Journal Article Pages 1-5 DOI 10.1007/s00340-011-4583-3 Authors Y. Monnai, Department of Information Physics and Computing, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku Tokyo, 113-8656 Japan H. Shinoda, Department of Information Physics and Computing, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku Tokyo, 113-8656 Japan H. Hillmer, Institute of Nanostructure Technologies and Analytics, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    It is shown that the resonance features analogous to the well known optic Wood-type anomalies can be observed in the THz region for diffraction at periodically profiled semiconductor surfaces. The analytical theory of such resonance processes caused by excitation of surface plasmon polaritons (SPPs) is developed. It is shown that strong resonance effects such as total suppression of the specular reflection (TSSR) can be achieved for rather small inclinations of harmonic gratings. The analytical theory predictions are confirmed by strict numerical simulations. The analytical approach presented allows one to find parameters of the gratings so that the resonance diffraction results in specific redistributions of the reflected energy between different diffraction channels. As an example we demonstrate parameters of the InSb biharmonic grating responsible for the TSSR accompanied by 50% reflection in the minus first diffraction order when the SPP is excited in the plus first diffraction order. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-011-4575-3 Authors I. S. Spevak, A.Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, 12 Acad. Proskury Av., Kharkiv, 61085 Ukraine M. A. Timchenko, A.Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, 12 Acad. Proskury Av., Kharkiv, 61085 Ukraine V. K. Gavrikov, Institute of Radio Astronomy, National Academy of Sciences of Ukraine, 4 Krasnoznamennaya Str., Kharkiv, 61002 Ukraine V. M. Shulga, Institute of Radio Astronomy, National Academy of Sciences of Ukraine, 4 Krasnoznamennaya Str., Kharkiv, 61002 Ukraine J. Feng, Jilin University, 2699 Qianjin Str., Changchun, 130012 China H. B. Sun, Jilin University, 2699 Qianjin Str., Changchun, 130012 China A. V. Kats, A.Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, 12 Acad. Proskury Av., Kharkiv, 61085 Ukraine Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The method of manufacturing and spectroscopic evaluation of the Er 3+ ions doped and Er 3+ –Yb 3+ co-doped SiO 2 –Al 2 O 3 –Na 2 CO 3 –CaO–PbO–PbF 2 oxyfluoride glass fibers is presented in the paper. Both optically active elements erbium and ytterbium were introduced into the batch in the form of fluorides. The X-ray diffraction (XRD) technique was applied at each stage of fibers manufacturing in order to control an amorphous structure of the preforms and fibers. Optical studies of glass preforms and fibers (reflection/transmission, absorption, emission, and excited state absorption (ESA)) were directed to examine their suitability as fiber amplifiers at 1.55 μm band. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-011-4578-0 Authors E. Augustyn, Department of Materials Science, Silesian University of Technology, Krasińskiego 8, 40-019 Katowice, Poland P. Stremplewski, Institute of Physics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland M. Rozanski, Institute of Physics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland C. Koepke, Institute of Physics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland G. Dominiak-Dzik, Polish Academy of Sciences, Institute for Low Temperatures and Structural Researches, Okólna 2a, Wrocław, Poland M. Kępińska, Department of Materials Science, Silesian University of Technology, Krasińskiego 8, 40-019 Katowice, Poland M. Żelechower, Department of Materials Science, Silesian University of Technology, Krasińskiego 8, 40-019 Katowice, Poland Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    Using the photonic crystal fiber (PCF) with the zero dispersion wavelength of 848 nm for the fundamental mode, the efficient anti-Stokes signal generations from 645 to 543 nm are realized by pumping in the normal dispersion region. When the pump average power increases from 200 to 500 mW, the output power of the anti-Stokes signal increases 8.46 times, the power ratio of the anti-Stokes signal at 543 nm to the residual pump is calculated as 22.6:1, and the conversion efficiency η in the experiment can be up to 46%. Moreover, good optical beam quality of the anti-Stokes signal can be achieved. Content Type Journal Article Category Rapid Communication Pages 1-4 DOI 10.1007/s00340-011-4760-4 Authors J.-H. Yuan, State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, P.O. Box 163#, BUPT, 100876 Beijing, China X.-Z. Sang, State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, P.O. Box 163#, BUPT, 100876 Beijing, China C.-X. Yu, State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, P.O. Box 163#, BUPT, 100876 Beijing, China L. Rao, State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, P.O. Box 163#, BUPT, 100876 Beijing, China Y. Han, Institute of Infrared Optical Fibers and Sensors, Physics Department, Yanshan University, 066004 Qinhuangdao, China G.-Y. Zhou, Institute of Infrared Optical Fibers and Sensors, Physics Department, Yanshan University, 066004 Qinhuangdao, China S.-G. Li, Institute of Infrared Optical Fibers and Sensors, Physics Department, Yanshan University, 066004 Qinhuangdao, China L.-T. Hou, Institute of Infrared Optical Fibers and Sensors, Physics Department, Yanshan University, 066004 Qinhuangdao, China Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    The optimal regimes for uniform texturing of a multicrystalline silicon (mc-Si) surface by pulsed laser radiation have been determined. The morphology and reflectance spectra of the texturized mc-Si have been studied. The laser-texturized mc-Si samples with reflectance of 2–3% over a wide spectral region have been produced. The influence of subsequent chemical etching on the reflective properties of the texturized surface has been analyzed. Content Type Journal Article Pages 1-6 DOI 10.1007/s00340-011-4625-x Authors D. A. Zuev, Institute on Laser and Information Technologies, Russian Academy of Sciences (ILIT RAS), 1 Svyatoozerskaya St., 140700 Shatura, Moscow Region, Russia O. A. Novodvorsky, Institute on Laser and Information Technologies, Russian Academy of Sciences (ILIT RAS), 1 Svyatoozerskaya St., 140700 Shatura, Moscow Region, Russia E. V. Khaydukov, Institute on Laser and Information Technologies, Russian Academy of Sciences (ILIT RAS), 1 Svyatoozerskaya St., 140700 Shatura, Moscow Region, Russia O. D. Khramova, Institute on Laser and Information Technologies, Russian Academy of Sciences (ILIT RAS), 1 Svyatoozerskaya St., 140700 Shatura, Moscow Region, Russia A. A. Lotin, Institute on Laser and Information Technologies, Russian Academy of Sciences (ILIT RAS), 1 Svyatoozerskaya St., 140700 Shatura, Moscow Region, Russia L. S. Parshina, Institute on Laser and Information Technologies, Russian Academy of Sciences (ILIT RAS), 1 Svyatoozerskaya St., 140700 Shatura, Moscow Region, Russia V. V. Rocheva, Institute on Laser and Information Technologies, Russian Academy of Sciences (ILIT RAS), 1 Svyatoozerskaya St., 140700 Shatura, Moscow Region, Russia V. Y. Panchenko, Institute on Laser and Information Technologies, Russian Academy of Sciences (ILIT RAS), 1 Svyatoozerskaya St., 140700 Shatura, Moscow Region, Russia V. V. Dvorkin, Skobeltsyn Institute of Nuclear Physics (MSU SINP), Lomonosov Moscow State University, 1(2), Leninskie gory, GSP-1, Moscow, 119991 Russia A. Y. Poroykov, Skobeltsyn Institute of Nuclear Physics (MSU SINP), Lomonosov Moscow State University, 1(2), Leninskie gory, GSP-1, Moscow, 119991 Russia G. G. Untila, Skobeltsyn Institute of Nuclear Physics (MSU SINP), Lomonosov Moscow State University, 1(2), Leninskie gory, GSP-1, Moscow, 119991 Russia A. B. Chebotareva, Skobeltsyn Institute of Nuclear Physics (MSU SINP), Lomonosov Moscow State University, 1(2), Leninskie gory, GSP-1, Moscow, 119991 Russia T. N. Kost, Skobeltsyn Institute of Nuclear Physics (MSU SINP), Lomonosov Moscow State University, 1(2), Leninskie gory, GSP-1, Moscow, 119991 Russia M. A. Timofeyev, Skobeltsyn Institute of Nuclear Physics (MSU SINP), Lomonosov Moscow State University, 1(2), Leninskie gory, GSP-1, Moscow, 119991 Russia Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We present an all-solid-state narrow-linewidth laser source emitting 670 mW output power at 671 nm delivered in a diffraction-limited beam. The source is based on a frequency-doubled diode-end-pumped ring laser operating on the 4 F 3/2 → 4 I 13/2 transition in Nd:YVO 4 . By using periodically poled potassium titanyl phosphate (ppKTP) in an external buildup cavity, doubling efficiencies of up to 86% are obtained. Tunability of the source over 100 GHz is accomplished. We demonstrate the suitability of this robust frequency-stabilized light source for laser cooling of lithium atoms. Finally, a simplified design based on intra-cavity doubling is described and first results are presented. Content Type Journal Article Pages 1-12 DOI 10.1007/s00340-011-4693-y Authors U. Eismann, Laboratoire Kastler Brussel, ENS, UPMC, CNRS UMR 8552, 24 rue Lhomond, 75231 Paris, France F. Gerbier, Laboratoire Kastler Brussel, ENS, UPMC, CNRS UMR 8552, 24 rue Lhomond, 75231 Paris, France C. Canalias, Department of Applied Physics, Royal Institute of Technology, AlbaNova Universitetscentrum, 10691 Stockholm, Sweden A. Zukauskas, Department of Applied Physics, Royal Institute of Technology, AlbaNova Universitetscentrum, 10691 Stockholm, Sweden G. Trénec, Laboratoire Collisions Agrégats Réactivité, Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes, LCAR, Université de Toulouse, Université Paul Sabatier and CNRS UMR 5589, 31062 Toulouse, France J. Vigué, Laboratoire Collisions Agrégats Réactivité, Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes, LCAR, Université de Toulouse, Université Paul Sabatier and CNRS UMR 5589, 31062 Toulouse, France F. Chevy, Laboratoire Kastler Brussel, ENS, UPMC, CNRS UMR 8552, 24 rue Lhomond, 75231 Paris, France C. Salomon, Laboratoire Kastler Brussel, ENS, UPMC, CNRS UMR 8552, 24 rue Lhomond, 75231 Paris, France Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We report a comparative study of carrier dynamics in semiconductor saturable absorber mirrors (SESAMs) containing InGaAs quantum wells and InGaAsN quantum wells (QWs). The static and dynamic reflectivity spectra were measured with a Fourier-transform-infrared-spectrometer and a pump-probe setup, respectively. The influence of rapid thermal annealing (RTA) on carrier dynamics was studied. Due to the reduction of defect states by RTA we observed an increase of the static reflectivity and an increase of the electron–hole recombination time. We demonstrate that nitrogen incorporation causes a decrease of the static reflectivity of the SESAMs, an increase of the modulation depth, and a reduction of the carriers’ recombination time. We also investigated the mode-locking behavior of the SESAMs in an Yb:YAG thin-disk laser oscillator. The highest pulse energies directly obtained from a laser oscillator under stable operation conditions were achieved when using a SESAM with InGaAsN quantum wells. Content Type Journal Article Pages 1-8 DOI 10.1007/s00340-011-4697-7 Authors F. Schättiger, Center for Applied Photonics and Department of Physics, University Konstanz, Box M700, 78457 Konstanz, Germany D. Bauer, Center for Applied Photonics and Department of Physics, University Konstanz, Box M700, 78457 Konstanz, Germany J. Demsar, Center for Applied Photonics and Department of Physics, University Konstanz, Box M700, 78457 Konstanz, Germany T. Dekorsy, Center for Applied Photonics and Department of Physics, University Konstanz, Box M700, 78457 Konstanz, Germany J. Kleinbauer, TRUMPF Laser GmbH & Co. KG, 78713 Schramberg, Germany D. H. Sutter, TRUMPF Laser GmbH & Co. KG, 78713 Schramberg, Germany J. Puustinen, Tampere University of Technology, Korkeakoulunkatu 3, 33720 Tampere, Finland M. Guina, Tampere University of Technology, Korkeakoulunkatu 3, 33720 Tampere, Finland Journal Applied Physics B: Lasers and Optics Online ISSN 1432-0649 Print ISSN 0946-2171

Description:    We present a theoretical and experimental study of a target-in-the-loop (TIL) high-power adaptive phase-locked fiber laser array. The system configuration of the TIL adaptive phase-locked fiber laser array is introduced, and the fundamental theory for TIL based on the single-dithering technique is deduced for the first time. Two 10-W-level high-power fiber amplifiers are set up and adaptive phase locking of the two fiber amplifiers is accomplished successfully by implementing a single-dithering algorithm on a signal processor. The experimental results demonstrate that the optical phase noise for each beam channel can be effectively compensated by the TIL adaptive optics system under high-power applications and the fringe contrast on a remotely located extended target is advanced from 12% to 74% for the two 10-W-level fiber amplifiers. Content Type Journal Article Pages 1-7 DOI 10.1007/s00340-011-4692-z Authors R. Tao, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China Y. Ma, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China L. Si, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China X. Dong, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China P. Zhou, College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, 410073 China Z. 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:    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