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  • 1
    Electronic Resource
    Electronic Resource
    Valence-band mixing effects on the gain and the refractive index change of quantum-well lasers (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4056-4064 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of valence-band mixing on the gain and on the refractive index change of the quantum-well laser and the effect of an applied electric field perpendicular to the quantum wells for gain switching are studied theoretically. Our calculations are based on the multiband effective-mass theory (k⋅p method) and the density-matrix formalism with the intraband relaxation taken into account. First, we calculate the nonparabolic valence-band structure by the finite difference method after making a unitary transformation of the Luttinger-Kohn Hamiltonian. The calculated gain for our model shows remarkable differences in both spectral shape and peak amplitude as compared with those for the conventional model of the parabolic valence band. The peak gain is reduced considerably and the gain spectrum is more symmetric in our model compared with that for the conventional model. The refractive index change shows a negative increment in the active region for both the TE and TM polarizations resulting in the antiguidance. However, the TM polarization shows more negative change which would result in the suppression of the TM modes as compared with the TE modes. As another example, the perpendicular electric field effects on the quantum-well laser with lateral current injection are also calculated. A red shift and a reduction of the gain spectrum are shown when an electric field is applied. This may have applications as a tunable and high-speed switching quantum-well laser.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341339
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  • 2
    Electronic Resource
    Electronic Resource
    Mode selectivity study of vertical-cavity surface-emitting lasers (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 726-728 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mode selectivity of an air-post index-guided vertical-cavity surface-emitting laser structure operating at 1550 nm is investigated using a full-vector Maxwell-equation solver with a finite-difference time-domain method. The resonance wavelengths, quality factors, and spatial field distributions are calculated for the three lowest-order modes. Transverse-mode competition is quantitatively described as a function of the cavity size and the pillar etch depth. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121981
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  • 3
    Electronic Resource
    Electronic Resource
    Red shifting the intersubband response of quantum-well infrared photodetectors by thermal annealing (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4737-4740 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Selectively red shifting the photoresponse of intersubband GaAs/Al0.25Ga0.75As multiple-quantum-well (MQW) infrared photodetectors (QWIPs) by furnace and rapid thermal annealing is explored. Selective interdiffusion of the MQW is achieved by dielectric encapsulating (SiO2 or Si3N4) the surface. The high dark current of annealed QWIPs is attributed to dopant out-diffusion from the QWs into the barriers. Declining responsivities result from reduced carrier density in the QW and a red shift of the intersubband transition energy. In this work, the intersubband energy is determined by the Fourier synthesis model and compared with experimental results (further confirming the interdiffusion mechanism). Minimal dark current and responsivity degradation is observed for Si3N4-encapsulated QWIPs red shifted by 1 μm © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363456
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  • 4
    Electronic Resource
    Electronic Resource
    Modeling of self-electro-optic-effect devices (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1388-1397 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed comparison is presented between a comprehensive theoretical model, which uses the linewidth as the only fitted parameter, and a consistent set of experimental data for (i) the electro-optical properties of quantum-well (QW) modulators and (ii) the input power versus output power characteristics of interband self-electro-optic-effect devices (SEEDs). The model, which is founded on basic principles, includes excitonic effects and employs the depletion approximation to relate the applied bias to the electric field and to phenomenologically approximate the internal quantum efficiency. It is shown that this model is able to emulate and predict the behavior of QW modulators and SEEDs very well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354897
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  • 5
    Electronic Resource
    Electronic Resource
    Bending loss in optical waveguides for nonplanar laser array applications (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2513-2520 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical transmission loss in dielectric waveguide bends is investigated using the finite-difference time-domain approach. An absorbing boundary condition, applied to reduce the size of the mesh, is proven to work very well for the waveguide structure. The desired modes are excited using the solution of a one-dimensional waveguide structure. The bending loss is then obtained using the methods of overlap integral and least-square fit. The structures of multiple-bend waveguides are analyzed. It is shown that the coupling between neighboring bends leads to direct transmission to the waveguide section on the aligned plane in addition to the transmission through the zigzag path. The bending loss in nonplanar laser arrays is investigated in detail. The possibility of having a shallow groove depth laser array is then discussed. Lateral lasing is prohibited by the radiation loss due to the bend. It is observed that the optical coupling between neighboring emitters is enhanced by the shallow groove depth, implying that phase-locked array modes can be obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351369
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  • 6
    Electronic Resource
    Electronic Resource
    Inter-miniband optical absorption in a modulation-doped AlxGa1−xAs/GaAs superlattice (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 6617-6624 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Theoretical calculations of the optical absorption between the conduction subbands in a modulation-doped AlxGa1−xAs-GaAs superlattice are presented. The electronic subband structures, including both the couplings between different quantum wells and the band bending due to screening effects, are calculated self-consistently by solving simultaneously the Schrödinger and the Poisson equation. Linear intersubband absorption in the superlattice is then calculated and the absorption spectra show interesting line shapes which reflect the joint density of states between different subbands. The dependence of the absorption (energy-band width, resonant absorption energy, and magnitude of peak absorption coefficient) on device parameters such as doping concentration, well width, barrier width, and aluminum mole fraction in the barrier, which are useful for the design of infrared detectors, is also investigated. These theoretical results are also compared with experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348875
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  • 7
    Electronic Resource
    Electronic Resource
    Optical transitions in a parabolic quantum well with an applied electric field—analytical solutions (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 2822-2826 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Both interband and intersubband optical transitions in a parabolic quantum well with an applied electric field are investigated. The wave functions for the electrons and holes are those of the displaced harmonic oscillators, which are shifted in opposite directions. The dipole moment matrices, the absorption coefficients, and the changes in the refractive indices are evaluated with the intrasubband relaxations taken into account. Interesting electroabsorption and electro-optic effects are presented analytically and numerically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342719
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  • 8
    Electronic Resource
    Electronic Resource
    Optical gain measurements based on fundamental properties and comparison with many-body theory (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 2945-2952 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present high accuracy measurements of gain, loss, and transparency energy in long-wavelength semiconductors based on a hybrid approach using the fundamental relationship between the gain and the spontaneous emission spectra. Independent measurements of optical gain, transparency energy, and loss show the accuracy and validity of this technique. These results are compared with those obtained by the non-Markovian gain model with many-body effects under the spontaneous emission transformation method. It is found that the hybrid approach for the gain spectrum alleviates many of the problems related to the poor signal to noise ratio in the amplified-spontaneous emission near and below the band edge. The theoretical spectra compare well with the measured spectra for both the transverse electric and transverse magnetic polarizations. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.371153
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  • 9
    Electronic Resource
    Electronic Resource
    Model of the field-effect quantum-well laser with free-carrier screening and valence band mixing (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 6143-6149 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of free-carrier screening and valence band mixing on gain-switching characteristics of the field-effect quantum-well laser are studied theoretically. Our analysis is based on the multiband effective mass theory and the density matrix formalism with the intraband relaxation taken into account. We calculate the electronic structure of the quantum well by solving simultaneously the multiband effective mass equations for the envelope functions with Poisson's equation. It is found that the free-carrier screening affects considerably both electronic properties (band structure and wave functions) and gain-switching characteristics by reducing the electric field and charge separation in the quantum well when the gate field is applied across the quantum well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342118
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  • 10
    Electronic Resource
    Electronic Resource
    A field-effect quantum-well laser with lateral current injection (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 440-442 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polarization-dependent gain switching in a field-effect quantum-well laser with lateral current injection is studied. We use the k⋅p method for the optical dipole matrix and take into account the intraband relaxation. Gain switching is achieved by the field effect from a gate terminal in a lateral current injection quantum-well laser structure. It is shown that the peak gain exhibits a red shift and the peak-gain amplitude decreases with an increasing electric field for the TE mode. The TM mode is less affected by the external field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341214
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