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  • 1
    Electronic Resource
    Electronic Resource
    Formation dynamics of layer-by-layer self-assembled films probed by second harmonic generation (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 3956-3960 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We investigate the formation dynamics of self-assembled polyelectrolyte multilayers on glass substrates by in situ and ex situ second harmonic generation (SHG) measurements and atomic force microscopy (AFM). The time dependence of the SHG signal during the adsorption process is attributed to a time dependent surface potential of the polyelectrolyte film. The dynamics can be quantitatively understood using a random sequential adsorption (RSA) model for the buildup of a film consisting of polyelectrolyte disks with polydisperse sizes. Differences between wet and dry films are also investigated. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1495839
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  • 2
    Electronic Resource
    Electronic Resource
    Carrier capture into InAs/GaAs quantum dots via multiple optical phonon emission (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 1180-1183 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed nondegenerate optical pump–probe experiments with subpicosecond laser pulses to investigate the dynamics of carrier capture into self-assembled InAs/GaAs quantum dots. For low excitation intensities the capture rate depends only slightly on excitation density, whereas a clear dependence on crystal temperature is observed. This temperature dependence can be explained by assuming that the emission of four longitudinal optical (LO) phonons and one longitudinal acoustic phonon is the dominant capture process for electrons. This assumption is consistent with the finding that, for electrons in the conduction band, the energetic separation between the single quantized quantum dot state and the onset of the two-dimensional states of the InAs wetting layer is slightly more than the energy of four LO phonons. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1333718
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  • 3
    Electronic Resource
    Electronic Resource
    Capture and thermal re-emission of carriers in long-wavelength InGaAs/GaAs quantum dots (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3968-3970 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate the ultrafast carrier dynamics in metalorganic chemical vapor deposition-grown InGaAs/GaAs quantum dots emitting at 1.3 μm. Time-resolved photoluminescence upconversion measurements show that the carriers photoexcited in the barriers relax to the quantum-dot ground state within a few picoseconds. At low temperatures and high carrier densities, the relaxation dynamics is dominated by carrier–carrier scattering. In contrast, at room temperature, the dominant relaxation process for electrons is scattering between quantum-dot levels via multiple longitudinal optical (LO)-phonon emission. The reverse process, i.e., multiple LO-phonon absorption, governs the thermal re-emission of electrons from the quantum-dot ground state. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1421235
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  • 4
    Electronic Resource
    Electronic Resource
    Dynamics of amplified spontaneous emission in InAs/GaAs quantum dots (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 3507-3509 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate the dynamics of amplified spontaneous emission (ASE) in self-assembled InAs/GaAs quantum dots, using pulsed optical excitation of an edge-emitting sample at room temperature. A material gain of 1.5×104 cm−1 is determined for 800 nm excitation with 1.5 μJ/cm2 pulses. Using photoluminescence up-conversion, we show that increases in both electron–hole pair density and photon density in the excited stripe cause a significant decrease in the decay time from 2.2 ns, corresponding to spontaneous emission, to about 0.9 ns, corresponding to stimulated emission or ASE. A carrier capture time of 10 ps limits the onset of the ASE process for short stripe lengths. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126689
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  • 5
    Electronic Resource
    Electronic Resource
    Spectroscopy of single metallic nanoparticles using total internal reflection microscopy (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2949-2951 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have developed a simple, fast, and flexible technique to measure optical scattering spectra of individual metallic nanoparticles. The particles are placed in an evanescent field produced by total internal reflection of light from a halogen lamp in a glass prism. The light scattered by individual particles is collected using a conventional microscope and is spectrally analyzed by a nitrogen-cooled charge-coupled-device array coupled to a spectrometer. This technique is employed to measure the effect of particle diameter on the dephasing time of the particle plasmon resonance in gold nanoparticles. We also demonstrate the use of this technique for measurements in liquids, which is important for the potential application of particle plasmons in chemical or biological nanosensors. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1323553
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  • 6
    Electronic Resource
    Electronic Resource
    A nearly diffraction limited surface emitting conjugated polymer laser utilizing a two-dimensional photonic band structure (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2310-2312 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated a mechanically flexible conjugated polymer laser utilizing distributed feedback due to a two-dimensional photonic band structure. An ultraviolet-embossing process is used for nanopatterning a plastic substrate. On top we spin-coat a ladder-type poly(p-phenylene) as the active laser medium. Upon optical pumping, we observe a low threshold and nearly diffraction limited monomode laser emission perpendicular to the surface. Our results are explained within a Laue formulation for the feedback mechanism in the two-dimensional organic photonic crystal. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1310207
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  • 7
    Electronic Resource
    Electronic Resource
    Electrically controlled light scattering with single metal nanoparticles (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 171-173 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A concept to electrically control the scattering of light is introduced. The idea is to embed noble metal nanoparticles in an electro-optical material such as a liquid crystal in order to induce a spectral shift of the particle plasmon resonance by applying an electric field. Light scattering experiments on single gold nanoparticles show that spherically shaped nanoparticles become optically spheroidal when covered by an anisotropic liquid crystal. The two particle plasmon resonances of the optically spheroidal gold nanoparticles can be spectrally shifted by up to 50 meV when electric fields of more than 10 kV/cm are applied. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1491003
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  • 8
    Electronic Resource
    Electronic Resource
    An optically controllable terahertz filter (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2821-2823 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using a mixed type-I/type-II GaAs/AlAs multiple-quantum-well sample, we have demonstrated an optically controllable and tunable terahertz (THz) filter. Long-lived electron–hole pairs in the quantum wells allow for efficient THz attenuation over a large THz spot size (2 mm) for extremely low optical cw power. This sample can also be used as an optically tunable THz phase shifter. The optically induced change of the GaAs quantum wells from a dielectric to a conducting material leads to the observed attenuation and the shifting of the THz wave forms. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126484
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  • 9
    Electronic Resource
    Electronic Resource
    Launching surface plasmons into nanoholes in metal films (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 140-142 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate optical transmission through individual nanometer-sized holes in opaque metal films using scanning near-field optical microscopy. We show unambiguously that excitation and lateral propagation of surface plasmons support the light transmission through these nanoholes. The direction of the surface plasmon propagation is given by the light polarization, thus controlled addressing of individual holes is possible. In addition, we find characteristic interference effects due to scattering of surface plasmons off holes. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125682
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrafast switch-off of an electrically pumped quantum-dot laser (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 1177-1179 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the subpicosecond switch-off of the emission of an electrically pumped quantum-dot (QD) laser with perturbation by a 100 fs optical pulse. The observed effect is in contrast to known ones for quantum-well laser diodes. This is explained by unique properties of the QDs, namely by the fast modal gain saturation and localization-enhanced intraband absorption. The QD laser response can be described in terms of hot carrier absorption in the barrier states via intraband optical transitions leading to the transient suppression of the laser mode and, hence, to the switch-off. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1500431
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