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Quantum Electronics, IEEE Journal of

Issue 5 • Date May 2006

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Displaying Results 1 - 15 of 15
  • Theoretical investigation of excitonic gain in ZnO--MgxZn1-xO strained quantum wells

    Page(s): 455 - 463
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    Free-excitonic gain of wurtzite ZnO--MgxZn1-xO quantum wells(QWs) is studied theoretically. The valence band structure of ZnO--MgxZn1-xO QWs with the consideration of biaxial strain and exciton-phonon interaction is calculated based on a 6×6 Hamiltonian. From the available experimental data, the band offset ratio and conduction band deformation potential of ZnO--MgxZn1-xO QWs are found to be 60/40 and -6.8eV, respectively. The influence of biaxial strain on the peak free-excitonic gain of ZnO--MgxZn1-xO QWs for various well-width and mole fraction of Mg is also investigated. View full abstract»

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  • Gain characteristics of asymmetric multiple quantum-well lasers

    Page(s): 464 - 470
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB) |  | HTML iconHTML  

    The spectra and gain characteristics were investigated for an asymmetric multiple quantum-well (AMQW) laser with two wide and two narrow QWs. It is reported that the laser initially lased on a long wavelength corresponding to the lowest energy transition of the wide well then switched to a short wavelength that was red-shifted more than 50 nm off the lowest energy transition of the narrow well. Correspondingly, the gain spectrum is much narrower than predicted by a free carrier gain theory. This large red wavelength shift or narrowing of the gain spectrum could not be explained by the present gain theories, while it could be explained satisfactorily by the measured gain spectra of QW lasers. This indicates that an accurate gain theory is required to predict the performance of AMQW lasers. View full abstract»

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  • High gain effects for solid-state impact-ionization multipliers

    Page(s): 471 - 476
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    We report the demonstration of a current amplification device, built from silicon and based on impact ionization, which can be cascaded to achieve very high gains. Arbitrary current sources including photodiodes can be interfaced with this device. Testing was done by amplifying the output signal from an independent silicon photodiode. Current gains over 600 were measured for initial photocurrents of 10 nA when two amplifying devices were cascaded together. Additionally, the gain saturation phenomenon of the amplifier due to space-charge effects is investigated. The measured gain saturation is observed to match very well with theoretical predictions. We also present guidelines for obtaining high current gain from the cascaded structure while avoiding gain saturation. Because of the low-noise gain mechanism employed, this device is of potential interest to a variety of fields requiring high-sensitivity optical or electronic detection. View full abstract»

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  • Tapping light from waveguides by high-order mode excitation and demultiplexing

    Page(s): 477 - 482
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    A novel high-performance optical tap with low wavelength-dependent loss(WDL), polarization-dependent loss (PDL), and excess loss is described. The tap is based on exciting a high-order mode by an abrupt change in the waveguide profile, and then tapping the optical power in the high-order mode by using a modal-demultiplexer. The tap can be designed to give a tapping ratio in the range of -30 to -10 dB over a wavelength range of 1510-1640 nm. In addition, it is shown that the tapping ratio is tolerant to process variations, repeatable and predictable, enabling the design to be implemented in a single process run, with no need for additional fine-tuning iterations, while achieving a high process yield. We show that measurements are in good agreement with simulated results. In the tap channel we measured 0.3 dB WDL and 0.2-dB PDL over the C- and L- bands, while the signal in the main channel was virtually uncontaminated relative to a plain single-mode reference waveguide. View full abstract»

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  • Edge- and end-pumped slab lasers with both efficient and uniform pumping

    Page(s): 483 - 489
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    In conventional high-power slab lasers, the design is often a compromise between pump absorption efficiency and uniformity. In this paper, both are studied for diode-array-pumped slab lasers. We explore a method with which each can be separately optimized, so it becomes possible to have both high efficiency and uniformity in slab lasers with long optical pump paths. The method is applicable to composite and ceramic crystal slab lasers. View full abstract»

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  • Proton-implanted shallow-ridge quantum-cascade laser

    Page(s): 490 - 493
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1104 KB) |  | HTML iconHTML  

    We demonstrate a shallow-ridge quantum-cascade laser (QCL) with performance comparable or better than that of deep-ridge QCLs fabricated from the same wafer. The shallow-ridge QCL emits at ≈4 μm with a 4.6-4.8 kA/cm2 threshold current density at room temperature which is similar to the deep-ridge QCL. At the same time the shallow-ridge QCL shows a better temperature stability, T0=160 K, than the deep-ridge QCL, with T0=120 K. The increase in the characteristic temperature of the shallow-ridge laser compared to the deep-ridge laser results from the improved heat dissipation out of the laser ridge through the lateral heat flow. Lateral spreading of the injection current-usually a drawback of shallow-ridge lasers-is suppressed by proton implantation into the strain-compensated InGaAs-AlAs active region layers on either side of the ridge. In contrast to the case of In0.53Ga0.47As layers and of In0.53Ga0.47As-In0.52Al0.48As heterostructures lattice matched to InP, the proton implantation of strain-compensated In0.73Ga0.27As-AlAs heterostructure on InP creates deep (180 meV) carrier traps, resulting in this material being electrically insulating even at room temperature. View full abstract»

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  • Optical Design of InAlGaAs Low-Loss Tunnel-Junction Apertures for Long-Wavelength Vertical-Cavity Lasers

    Page(s): 494 - 499
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB)  

    We report on the optical design of thin selectively etched InAlGaAs tunnel-junction apertures for the realization of optically efficient long-wavelength vertical-cavity surface-emitting lasers (VCSELs). These apertures were designed to introduce minimal optical loss to the structure, facilitate single-mode operation, and yield optical mode diameters that better match the injected current density profile. We then demonstrate InP-based VCSELs emitting at 1304 nm utilizing these low-loss InAlGaAs apertures, resulting in optically efficient low-loss devices with differential quantum efficiencies of up to 60%. View full abstract»

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  • Optimization of doubly Q-switched lasers with both an acoustic-optic Modulator and a Cr4+-doped saturable absorber

    Page(s): 500 - 508
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB) |  | HTML iconHTML  

    By considering the Gaussian spatial distributions of the intracavity photon density and the initial population-inversion density as well as the influence of the acoustic-optic (AO) Q-switch, we provide the coupled rate equations for a doubly Q-switched laser with both an AO modulator and a Cr 4+ -doped saturable absorber (SA). These coupled rate equations are solved numerically. The key parameters of an optimally coupled doubly Q-switched laser are determined,and a group of general curves are generated for the first time. These key parameters include the optimal normalized coupling parameter, the optimal normalized SA parameters and the normalized parameters of the AO Q-switch, which can maximize the output energy. Meanwhile, the corresponding normalized energy, the normalized peak power and the normalized pulsewidth are given. The curves clearly show the dependence of the optimal key parameters on the parameters of the gain medium, the SA, the AO Q-switch,the resonator and the spatial distributions of the intracavity photon density. Sample calculations for a diode-pumped Nd3+:YVO4 laser with both an AO modulator and a Cr4+ :YAG SA are presented to demonstrate the use of the curves and the related formulas. View full abstract»

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  • Fast all-optical flip-flop memory exploiting the electric field nonlinearity of coherent laser amplifiers

    Page(s): 509 - 516
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1032 KB) |  | HTML iconHTML  

    The coherent nonlinear feedback in an integrated optical flip-flop is studied in order to demonstrate device applications of laser amplifiers operated above the laser threshold. The nonlinear feedback is provided by the stabilizing fields of the laser amplifiers, interfering with coherent optical reference fields. In both stable states of the flip-flop, the nonlinear feedback allows the laser amplifiers to maintain an ever present photon population in the laser modes and to have an approximately constant carrier population. This enables faster response (switching times below 25 ps are reached in this work)than in conventional active optical flip-flop structures. The operation of the flip-flop is studied using a rate equation model accounting for the carrier densities and the complex electric fields in the different cavity modes of the laser amplifiers. View full abstract»

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  • Characterization of diode-pumped laser operation of a novel Yb:GSO Crystal

    Page(s): 517 - 521
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (960 KB) |  | HTML iconHTML  

    We report what is believed to be the first demonstration of the laser action of Yb3+-doped Gd2SiO5 (Yb:GSO)crystal pumped by a 940-nm laser diode at room temperature. The threshold of laser generation is only 0.85 kW/cm2, which is smaller than the theoretic threshold of Yb:YAG (1.54 kW/cm2). The laser wavelength is 1090 nm. With a 2.5% output coupler, the maximum output power is 415 mW under a pump power of 5W. By using the SESAM, the Q-switched modelocking and CW mode-locked operations are demonstrated. View full abstract»

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  • Table of contents

    Page(s): 522
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    Freely Available from IEEE
  • [Front cover]

    Page(s): 523
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    Freely Available from IEEE
  • IEEE Journal of Quantum Electronics publication information

    Page(s): 524
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    Freely Available from IEEE
  • Special issue on optical code in optical communications and networks

    Page(s): 525
    Save to Project icon | Request Permissions | PDF file iconPDF (119 KB)  
    Freely Available from IEEE
  • IEEE Journal of Quantum Electronics information for authors

    Page(s): 526
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    Freely Available from IEEE

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