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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2866-2872 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The carrier recombination rates in GaAs and strained InGaAs–GaAs single-quantum-well lasers of varying well width and potential depth, respectively, have been measured at 300, 195, and 77 K. For the InGaAs quantum wells (QWs), the carrier lifetime saturates at high inversion, with both the Shockley–Read (SR) lifetime and the saturation lifetime showing substantial reductions with decreasing temperature. The large reduction in the SR lifetime may be attributed to the increased effectiveness of acceptor ions as trap sites, due to the reduced carrier momentum at lower temperature. In a similar vein, the saturation lifetime is also reduced, due to the enhanced carrier confinement in the QW, brought about by the decrease in the carrier thermalization. For the GaAs QWs at 300 K, the saturation lifetime decreases as the well width is increased. The recombination rate law of bulk material is inadequate to predict the recombination rates in these QWs. Consequently, a local recombination model has been developed which accurately predicts the observed lifetime saturation behavior as a function of well width, potential depth, and temperature. Further, T0 of 95 and 162 K are calculated for the shallow and deep QW lasers, respectively. This calculation suggests that it is the temperature dependence of the differential gain that is the dominant factor in setting the temperature sensitivity of the InGaAs QW lasers.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 1420-1429 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Many mid-infrared semiconductor laser sources are now being developed with superlattice active regions. Calculations of gain, index of refraction, and intervalence subband absorption for these laser materials require accurate subband energies, wave functions, and radiative matrix elements. We have recently begun using a solution method based on the empirical pseudopotential method (EPM). This method shows particular strength in analyzing structures with short periods or thin layers, for which the standard method, based on k⋅p perturbation theory and the envelope function approximation, may be problematical. We will describe the EPM applied to bulk solids and then demonstrate our direct generalization of the method for applications to superlattice structures. Calculations for recently developed mid-infrared semiconductor lasers using type-II superlattice active regions will be used to illustrate the method. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2921-2925 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have linearized the equations for propagation of the beam of light in a semiconductor optical amplifier about an operating point and have derived the rate of growth of small sinusoidal perturbations of the phase and modulus of the complex field amplitude. The perturbations grow if the spatial frequency is below a critical value that depends on the intensity of the field at the operating point. For spatial frequencies above the critical value, the perturbations die out. The critical spatial frequency decreases as the intensity increases above a certain value. In other words, the tendency to filament becomes weaker as the intensity increases above a certain value. Computer-generated solutions of the propagation and gain equations are included to illustrate the growth of filaments as the plane-wave intensity changes in an amplifier.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 84-88 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present linewidth measurements on AlGaAs double heterostructure lasers as a function of temperature and power. The data, which plot observed linewidth as a function of reciprocal power, reveal decreasing slopes and increasing vertical axis intercepts, or power independent linewidths, with falling temperature, consistent with previous experimental observation [D. Welford and A. Mooradian, Appl. Phys. Lett. 40, 560 (1982)]. To explain the power independent linewidth broadening observed in these continuous wave single frequency lasers, we propose that carrier heating processes create a thermal nonequilibrium between electrons and the semiconductor lattice, and that this leads to a power dependent linewidth enhancement factor. From a carrier thermal model we find that the power independent linewidth is mediated by the longitudinal optical (LO)-phonon lifetime (τLO); as τLO is increased (for example, by decreasing the lattice temperature), the noneqilibrium condition is enhanced, and, consequently, the power independent linewidth increases. © 1997 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 836-838 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This letter presents a technique for determining carrier lifetimes, which does not require a fast detector or rely on an experimentally complex implementation. The technique is based both on a measurement and a parallel calculation: (1) A Hakki–Paoli [J. Appl. Phys. 44, 4113 (1973)] measurement of modal gain versus current density, g(J), and (2) A theoretical determination of the modal gain versus carrier sheet density, g(N). Once the gain relationships have been determined, the carrier sheet density N can be functionally related to the current density J and the lifetime determined. We demonstrate this method on two InGaAs single quantum well lasers. This method may prove particularly useful for carrier lifetime estimations in long-wavelength semiconductor lasers. © 1998 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 937-939 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We observe modification of the spontaneous emission spectrum emitted through the substrate of a quantum well semiconductor laser. The effect is driven by the proximity of the quantum well active region to the p-side electrical contact of the device, representing an excellent example of cavity quantum electrodynamics. Modification of the spontaneous emission rate and spectrum can be substantial; it must be accounted for in order to infer modal gain or carrier heating phenomena in the device correctly. © 1997 American Institute of Physics.
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  • 7
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a novel high power semiconductor laser that employs a shaped unstable resonator waveguide to maintain fundamental spatial mode operation at high power levels. We call this device the SHUR (shaped unstable resonator) laser. By photoetching and regrowth we locate a secondary, nonplanar antiguide, beneath the main part of the waveguide. The lasing mode couples to this secondary guide and experiences lateral antiguiding, which is the basis of the unstable resonator action. Prototype versions of the SHUR laser show a maximum pulsed output power of 770 mW per facet. The focused beam is dominated by a single lobe that contains 47% of the output power. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2730-2732 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The carrier recombination rate in strained InGaAs–GaAs single quantum well lasers of varying potential depth, as determined by the well/barrier band offsets, is investigated both theoretically and experimentally. At higher current densities (J≥300 A cm−2), the carrier lifetime saturates. The saturation lifetime in the shallow well is considerably longer (τsat∼4.2 ns) than in the deep quantum wells (QWs) (τsat∼0.9 ns). The recombination rate law of bulk material is inadequate to predict the recombination rates in the InGaAs QWs. Consequently, a local recombination model has been developed which accurately predicts the lifetime saturation behavior observed in the QWs. Overall, it appears that an adequate model of carrier recombination is dependent both on material composition factors (i.e., accurate recombination coefficients) and on the detailed electron-hole densities which are influenced by structural factors such as QW potential depth and QW width. © 1995 American Institute of Physics.
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  • 9
    Publication Date: 1997-02-24
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 10
    Publication Date: 1996-09-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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