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Quantum Electronics, IEEE Journal of

Issue 3 • Date March 2007

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Displaying Results 1 - 16 of 16
  • [Front cover]

    Page(s): C1
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  • IEEE Journal of Quantum Electronics publication information

    Page(s): C2
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  • Table of contents

    Page(s): 213 - 214
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  • Extension of Coupled Mode Analysis to Periodic Large Arrays of Identical Waveguides for Photonic Crystals Applications

    Page(s): 215 - 224
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1159 KB) |  | HTML iconHTML  

    Coupled-mode theory, developed for several parallel waveguides, is extended to the case of infinite 2-D photonic crystals. Periodic boundary conditions, applied to a system of coupled identical waveguides, are used to compute the photonic band structures. This approach is shown to be more efficient than the usual numerical methods when tested on finite, but large-sized, arrays. Photonic crystals made of single-mode and multimode waveguide arrays are examined View full abstract»

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  • Inside Vertical-Cavity Surface-Emitting Lasers: Extracting the Refractive Index From Spatial-Spectral Mode Images

    Page(s): 225 - 229
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (513 KB) |  | HTML iconHTML  

    We present a method to extract the internal effective refractive index of a vertical-cavity surface-emitting laser (VCSEL) from its transverse mode images. High spatial and spectral resolution mode images of an oxide-guided VCSEL were obtained using an etalon filter and an imaging spectrometer. The refractive index and the oxide radius were extracted from the field intensity distribution and the spectral wavelength of the laser modes. The procedure was repeated at two different currents and both gave a refractive index step of 0.046 plusmn 0.006 with a 14.1-mum oxide diameter. With several degrees of freedom for error available in the refractive index extraction, this method may be extended to ion-implanted, photonic crystal, and noncircular devices View full abstract»

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  • 640 × 512 Pixels Long-Wavelength Infrared (LWIR) Quantum-Dot Infrared Photodetector (QDIP) Imaging Focal Plane Array

    Page(s): 230 - 237
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1637 KB) |  | HTML iconHTML  

    Epitaxially grown self-assembled InAs-InGaAs-GaAs quantum dots (QDs) are exploited for the development of large-format long-wavelength infrared focal plane arrays (FPAs). The dot-in-a-well (DWELL) structures were experimentally shown to absorb both 45deg and normal incident light, therefore, a reflection grating structure was used to enhance the quantum efficiency. The devices exhibit peak responsivity out to 8.1 mum, with peak detectivity reaching ~1times1010 Jones at 77 K. The devices were fabricated into the first long-wavelength 640times512 pixel QD infrared photodetector imaging FPA, which has produced excellent infrared imagery with noise equivalent temperature difference of 40 mK at 60-K operating temperature View full abstract»

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  • Effectiveness of SiGe Buffer Layers in Reducing Dark Currents of Ge-on-Si Photodetectors

    Page(s): 238 - 242
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    The effectiveness of thin SiGe buffer layers in terminating threading dislocations and reducing photodiode dark current for Ge epitaxially grown on Si (001) has been investigated. The structural morphology of the films was studied by atomic force microscopy and transmission electron microscopy. The dark current of Ge on Si photodiodes can be reduced by over an order of magnitude by incorporating two different composition SiGe buffer layers. The origin of dark current and the effectiveness of thermal annealing the SiGe layers were also studied View full abstract»

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  • On the Evolution of Carrier Distribution and Wavelength Switching in Asymmetric Multiple Quantum-Well Lasers

    Page(s): 243 - 248
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (321 KB) |  | HTML iconHTML  

    The evolution of the carrier distribution with current in two different asymmetric multiple quantum laser structures was studied experimentally through measurements of electroluminescence (EL). The EL was measured through the substrates of lasers and provided information about the carrier distributions. The carrier concentration was observed to increase with current both below and above threshold, presumably owing to the change of threshold conditions. The switch of the lasing wavelength from long to short wavelength was explained by inhomogeneous broadening of the gain of the wells and by incomplete clamping of the carrier concentration above threshold, as inferred from the measured EL and gain spectra. The role of thermal effects was investigated by comparing the laser performance under continuous-wave and pulsed operation View full abstract»

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  • Theory of Optical Gain of Ge-SixGeySn1−x−y Quantum-Well Lasers

    Page(s): 249 - 256
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (370 KB) |  | HTML iconHTML  

    We develop a theoretical model for optical gain of a strained Ge--SixGeySn1-x-y quantum-well (QW) structure. By using a ternary SixGeySn1-x-y material system as the barriers, a tensile strained germanium QW with a direct band gap for the electron and hole confinements can be realized. We show our theoretical model for the strained band structure and the polarization dependent optical gain spectrum of the tensile strained germanium QW laser taking into account the carrier occupations in both the Gamma- and L-valleys of the conduction band. Reasonable material parameters are used to estimate the transition energy, optical gain spectrum, and effects of the carrier leakage in presence of the quantized subbands View full abstract»

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  • CW Laser Operation of KLu0.945Tm0.055(WO4)2ndash;KLu(WO4)2 Epilayers Near 2 μm

    Page(s): 257 - 260
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (261 KB) |  | HTML iconHTML  

    Thin epilayers of monoclinic KLu(WO4)2 doped with thulium are grown by liquid phase epitaxy on undoped KLu(WO4 )2 substrates. The epitaxial composites are optically characterized and implemented in a cavity, longitudinally pumped (normal to the layer) by a Ti:sapphire laser. Tunable (1894-2039 nm) continuous-wave laser operation is achieved with maximum slope efficiency as high as 64% with respect to the absorbed pump power at 802 nm. The output power is limited by the crystal absorption View full abstract»

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  • Bistability in Semiconductor Lasers With Polarization-Rotated Frequency-Dependent Optical Feedback

    Page(s): 261 - 268
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    Bistability in the emission frequency of a semiconductor laser subject to orthogonal-polarization optical feedback was recently observed experimentally by Farias in 2005, Phys. Rev. Lett. 94 173902 (2005). A frequency-sensitive filter (Cs-vapor cell) was placed in the way of the feedback beam to spectrally modulate the feedback power. Two different emission frequencies with the same output power were observed. This observation was understood in terms of a model that took into account the line shape of the filter and the empirical linear relation between the feedback-induced frequency shift and the feedback intensity. The model allowed to calculate steady states but not time-varying solutions. Here we present a rate-equation model that takes into account thermal and gain-saturation effects, and predicts a linear variation of the laser frequency with the feedback strength, together with a small power modulation. This model allows to study time-dependent solutions, and in particular, the transition between the two coexisting states. We show that numerical simulations using this model correctly reproduce the previous observed dynamics, and we present new experimental results in good agreement with our model for the laser response under orthogonal feedback View full abstract»

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  • Analytical Electromagnetic Solution for Bragg Mirrors With Graded Interfaces and Guidelines for Enhanced Reflectivity

    Page(s): 269 - 274
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB) |  | HTML iconHTML  

    Bragg mirrors, the key element of vertical-cavity surface-emitting lasers, always present graded interfaces when current is pumped through them, so as to reduce their series resistance and related heating problems. We present here an analytical solution for the electromagnetic fields in graded Bragg mirrors. It allows to generate reference reflection and transmission coefficients that are compared with those obtained by the staircase approximation method. Graded mirrors are then analyzed in detail and it is shown that, with an optimized design, higher reflectivity than in the abrupt scheme can be achieved View full abstract»

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  • Special issue on optical fiber sensors

    Page(s): 275
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  • Special issue on nanosensors for defense & security

    Page(s): 276
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  • 5th IEEE/LEOS Workshop on Fibres and Optical Passive Components (WFOPC 2007)

    Page(s): 277
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  • IEEE Journal of Quantum Electronics information for authors

    Page(s): 278
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Aims & Scope

The IEEE Journal of Quantum Electronics is dedicated to the publication of manuscripts reporting novel experimental or theoretical results in the broad field of the science and technology of quantum electronics..

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Meet Our Editors

Editor-in-Chief
Aaron R. Hawkins
Brigham Young University