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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of oxygen adsorption, absorption, and desorption on the Cu(111) surface (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 9167-9176 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The interaction of oxygen with the Cu(111) surface in ultrahigh vacuum (UHV) has been studied in the temperature range 400〈T〈800 K using second-harmonic generation (SHG) and x-ray photoelectron spectroscopy (XPS). When the clean surface is exposed to oxygen at pressures between 5×10−8 and 10−5 Torr and for T〈500 K, the SHG intensity decreases monotonically with exposure by more than one order of magnitude to a value which has no measurable temperature dependence. For T(approximately-greater-than)500 K, the SHG intensity passes through a minimum before achieving this constant value. The observation of this minimum is interpreted in terms of an outward relaxation of the Cu(111) surface as oxygen penetrates the subsurface region. When UHV conditions are restored for T(approximately-greater-than)600 K, the SHG intensity reverses its temporal dependence. These observations are consistent with initial incorporation of atomic oxygen into the subsurface region at a rate which is dependent on surface temperature and oxygen pressure and subsequent backdiffusion in UHV, driven by the oxygen concentration gradient near the surface. From experiments performed at different oxygen pressures and sample temperatures we establish rate constants for oxygen incorporation and surface outward relaxation as a function of temperature. The kinetics of oxygen incorporation determined from changes in the SHG intensity are compared with those derived elsewhere from ellipsometry studies. Differences yielded by the two experimental techniques are related to differences in monitored depths. Complementary XPS experiments suggest that sites occupied by the subsurface oxygen are characterized by tetrahedral symmetry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464424
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  • 2
    Electronic Resource
    Electronic Resource
    Nonlinear optical response of As+-ion implanted GaAs studied using time resolved reflectivity (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3287-3289 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transient reflectivity response of GaAs with a 2% excess As concentration (GaAs:As), prepared by As+ ion implantation, has been measured at photon energies near the band gap. Results are compared with similar measurements on implanted GaAs with a 0.01% excess As concentration, and unimplanted GaAs. For GaAs:As, the transient refractive index change Δn, is larger than, but of the opposite sign to that of unimplanted GaAs. The measured carrier lifetime of 1±0.1 ps is identical to that of low-temperature GaAs. The wavelength dependence of Δn indicates the presence of an induced absorption peak at photon energies near the band gap, which is attributed to band-gap renormalization. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116576
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  • 3
    Electronic Resource
    Electronic Resource
    Vertical-viewing electron cyclotron emission diagnostic for the DIII-D tokamak (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1611-1613 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The vertical-viewing electron cyclotron emission diagnostic on DIII-D will be used to assess the nonthermal electron distributions resulting from electron cyclotron heating and electron cyclotron current drive experiments. Electron cyclotron emission along a vertical chord is collected using an ellipsoidal focusing mirror and retroreflector (the latter to minimize wall reflections). The emission is then transported ∼20 m using a quasioptical transport system composed of eight lenses and three mirrors, and detected between the 2nd and the 10th harmonics by a fast-scanning (40-Hz) Michelson interferometer. The entire system has been aligned using a Gaussian beam simulator and absolutely calibrated in situ using a cold liquid-nitrogen bath. Details of the design, installation, and calibration will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140162
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  • 4
    Electronic Resource
    Electronic Resource
    Modification of the second-order optical susceptibility in AlxGa1−xAs by ion-beam induced amorphization (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 216-218 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical second-harmonic (SH) response of GaAs and Al0.6Ga0.4As bombarded with 1.2-MeV energy As+ ions has been measured for doses ranging from 5×1012 to 2×1014 ions cm−2. The measured SH response vanishes at an ion dose of 2×1014 ions cm−2 as a result of ion induced amorphization. Thermal annealing at 600 °C greatly reduced the damage induced optical absorption, for λ=1.06 μm light, but had no effect on the SH susceptibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112677
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  • 5
    Electronic Resource
    Electronic Resource
    Multilayer, nonlinear antiresonant waveguides for surface emitted optical mixing (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 118-120 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A multilayered core nonlinear antiresonant reflecting optical waveguide (NARROW) was used to generate surface emitted frequency doubled light. High efficiencies were obtained with the NARROW while simultaneously keeping optimum antiresonant conditions at the fundamental wavelength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109343
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  • 6
    Electronic Resource
    Electronic Resource
    Second harmonic generation in InGaAsP waveguides at 1.3 μm wavelength (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2090-2092 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the first surface emission of red light from an InGaAs waveguide, generated by the nonlinear mixing of two counterpropagating guided waves at wavelengths around 1.3 μm. A nine layer InGaAsP/InP heterostructure was grown by low pressure MOCVD on 〈100〉 InP substrate. All layers were n-doped with silicon to a level of 1.0×1017 cm−3. The structures functioned in both planar as well as ridge waveguide configurations. Measurements were performed with both a YAG laser and a semiconductor laser in the pulsed as well as the cw regime and were compared with theoretical calculations, used in the design of the structure. Red light was detected even in a single slab InGaAsP waveguide with a cw semiconductor laser diode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108316
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  • 7
    Electronic Resource
    Electronic Resource
    Patterning the second-order optical nonlinearity of asymmetric quantum wells by ion implantation enhanced intermixing (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 3097-3099 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The change in the second-order nonlinear susceptibility of an asymmetric quantum well (AQW) superlattice induced by ion beam-enhanced intermixing has been measured. The surface-emitted second-harmonic intensities radiated from implanted and masked areas of an AQW waveguide were measured and compared for incident wavelengths between λ=1480 and 1600 nm. Intermixing resulted in a 60 meV blueshift of the AQW band edge and a uniform suppression of the AQW second-order susceptibility, while the masked AQWs were unchanged. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121558
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  • 8
    Electronic Resource
    Electronic Resource
    Quasiphase matched surface emitting second harmonic generation in periodically reversed asymmetric GaAs/AlGaAs quantum well waveguide (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 2655-2657 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We experimentally demonstrate surface-emitting second harmonic generation in a waveguide containing asymmetric coupled GaAs/AlGaAs quantum wells. The nonlinear conversion efficiency is enhanced by reversing the asymmetric well orientation every coherence length, in order to quasiphase match the vertical second harmonic generation process. The measured spectrum of the asymmetric quantum well susceptibility is dominated by an excitonic peak at a pump frequency corresponding to half of the first electron-heavy hole transition energy. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118987
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  • 9
    Electronic Resource
    Electronic Resource
    Phonon-resolved photoluminescence at λ=1.55 μm from undulating Si0.5Ge0.5 epitaxial layers (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2430-2432 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Si0.5Ge0.5/Si multiquantum well structures are grown using a production-compatible ultrahigh vacuum chemical vapor deposition system. The structures are designed in order to obtain dislocation-free undulating strained layers. A photoluminescence emission corresponding to the direct "no phonon" transition is measured at energies systematically smaller than calculated for planar layers, implying that any increase in band gap due to elastic relaxation of the lattice strain at the undulation crests is compensated for by a confinement energy decrease together with a Ge accumulation at the undulation crests. The photoluminescence "no phonon" emission peaks at a wavelength that increases with nominal well thickness up to 1.55 μm. This opens the possibility of using dislocation-free silicon–germanium undulating layers as an absorber for photodetector applications at the telecommunication wavelengths of λ=1.3–1.55 μm. © 1998 American Institute of Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121395
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  • 10
    Electronic Resource
    Electronic Resource
    Low threshold optical bistable switching in an asymmetric λ/4-shifted distributed-feedback heterostructure (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1051-1053 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nonlinear optical response of an asymmetric λ/4-shifted distributed-feedback GaAs/AlAs heterostructure is investigated using numerical methods, and also demonstrated experimentally. This structure exhibited both optical switching and bistability at incident wavelengths near λ=884 nm. The observed bistability threshold of less than 1 kW cm−2 is more than an order of magnitude smaller than that of any previously measured distributed-feedback heterostructures. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114461
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