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Quantum Electronics, IEEE Journal of

Issue 6 • Date June 2011

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Displaying Results 1 - 25 of 25
  • [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): 754
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  • Improved Performance of an InGaN-Based Light-Emitting Diode With a p-GaN/n-GaN Barrier Junction

    Page(s): 755 - 761
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (649 KB) |  | HTML iconHTML  

    An InGaN-based light-emitting diode with a p-GaN/n-GaN barrier junction is fabricated and investigated. Due to the built-in potential induced by this junction, superior current spreading performance is achieved. In addition, the suppression of the current-crowding phenomenon yields a reduced parasitic effect. Therefore, under an injection current of 20 mA, improved behaviors, including lower turn-on voltage, lower parasitic series resistance, and reduced p-n junction temperature, are achieved. In addition, due to the improved current-spreading ability, longer life-time, driving at medium current injection (60 mA), as well as significantly enhanced electrostatic discharge performance, are obtained. View full abstract»

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  • Dynamics Scenarios of Dual-Beam Optically Injected Semiconductor Lasers

    Page(s): 762 - 769
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (553 KB) |  | HTML iconHTML  

    The nonlinear dynamics of a dual-beam optically injected semiconductor laser are studied. Most of the observed dual-beam injection dynamics can be understood from competitions of single-beam injection dynamics that are associated separately with each injection beam. Three general scenarios are identified and mapped for various combinations of detuning frequencies and injection strengths of the two injection beams. In Scenario A, simultaneous injection of two beams completely suppresses the dynamics due to separate single-beam injection and replaces them with the dynamics resulting from strong nonlinear interactions of the two injection beams. In Scenario B, simultaneous injection of two beams does not suppress the dynamics due to single-beam injection of one of the two beams but modifies such dynamics through nearly degenerate four-wave mixing with the other injection beam associated with the suppressed dynamics. In Scenario C, simultaneous injection of two beams does not suppress the dynamics due to single-beam injection of either of the two beams but allows the two dynamics to coexist and mix nonlinearly. View full abstract»

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  • Analysis of Path Length Sensitivity in Coherent Beam Combining by Spatial Filtering

    Page(s): 770 - 776
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (942 KB) |  | HTML iconHTML  

    The sensitivity to path length changes is analyzed in coherent beam combining architectures based on Fourier plane spatial filtering. Unlike superposition architectures based on 3-dB couplers and Dammann gratings, the supermodes of a two-laser spatially filtered cavity exhibit two distinctly different types of behavior depending on the path length error. When the error is small, the two modes present different cavity loss values and can be differentiated by gain. However, cavities containing path length errors greater than a critical value produce modes with identical losses and different resonant frequencies. Cavities with more than two elements exhibit similar behavior. Alternative filtering techniques are also discussed and compared. It is found that complementary filtering, where absorption spots are placed in the nulls of the intensity pattern in the Fourier plane, results in reduced power loss while preserving the same degree of modal discrimination. View full abstract»

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  • Model of the Self-Q-Switching Instability of Passively Phased Fiber Laser Arrays

    Page(s): 777 - 785
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    We present a simple model for self-pulsation instability in passively phased high power optical fiber amplifier arrays with external feedback. Its key features are, first, the feedback level's sensitivity, and thus that of the cavity Q-value, to small phase changes of the array fields, and, second, the effect of refractive index nonlinearity in the amplifiers. The model's prediction of an instability threshold for arrays of at least two amplifiers is confirmed by a linearized stability analysis of a system in ring-cavity geometry, and the magnitudes of predicted power levels are well within the domain of recent experiments. View full abstract»

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  • Analysis of Output Pulse Characteristics in Q -Switched Yb-Doped Fiber Laser

    Page(s): 786 - 794
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (726 KB) |  | HTML iconHTML  

    Characteristics of the output pulses of a high-peak-power Q-switched Yb-doped fiber laser are presented. A Q-switched fiber laser with 1.3 kW peak power and with typical pulse duration of 240 ns at 20 kHz modulation frequency was realized, variations of pulse duration, average power, peak power, and pulse energy with variation in the modulation frequency were studied. The effect of the modulation duty cycle (DC) on the Q-switched pulse characteristics was analyzed both theoretically and experimentally. It is shown that, for a particular pump power and repetition rate, the DC of modulation needs to be optimized to achieve high-peak-power single-pulse output. If the DC of modulation is long, satellite pulses of low peak power are also observed along with the main peak, when the DC is made short enough, the satellite pulses disappear and single peak pulses appear in the output. Theoretical analysis and simulation to predict the pulse build-up time, output pulse shape, and effect of modulation window time on the output pulse characteristic were carried out. Simulation results show good agreement with experimental results. This paper reported here will be useful in the development of high-peak-power Q -switched fiber lasers. View full abstract»

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  • Influence of Molecular Gases on the Lasing on the Self-Terminating He~\left(2^{1}P_{1}^{0}-2^{1}S_{0}\right) Transition

    Page(s): 795 - 802
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    Excitation with single and dual electron-beam pulses was used to investigate into the lasing on the self-terminating He (21P10-21S0) transition in mixtures of helium with various molecules. In pure helium the maximum lasing duration was found to be equal to 50 ns, this time being fairly well coincident with the calculated lasing duration. Restoration of lasing in the second pulse was observed following a time Δtmin >; 1.25 μs. Foreign molecular species admixed to helium enhance the relaxation rate of the metastable He(21S0) state, thus making the time Δtmin shorter until the pulses finally merge together. In the mixtures of helium with NH3 and H2O excited with 650-ns electron-beam pulses, the lasing duration of 600 ns was observed. Such duration indicates realization of a collisional quasi-continuous lasing mode. View full abstract»

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  • AlGaInP-Based LEDs With a {\rm p}^{+} -GaP Window Layer and a Thermally Annealed ITO Contact

    Page(s): 803 - 809
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    In this paper, indium-tin-oxide (ITO) films were deposited on p-type GaP films with a AuBe-diffused metal layer to form ohmic contacts. Without the AuBe diffused into p-GaP films, the ITO deposited on p-GaP showed a non-ohmic characteristic. After the AuBe diffused, the ITO deposited on p-GaP displayed a linear current-voltage characteristic and the specific contact resistance showed 2.63 × 10-4 ω-cm2. Furthermore, the specific contact resistance could be improved to 1.57 × 10-4 ω-cm2 when the sample post-ITO-deposition annealed at 400°C. The transmittance of ITO film almost was kept at 90% in the wavelength range of 400-700 nm after thermal annealing. These results revealed that the ITO films can be a suitable transparent current spreading layer for the fabrication of AlGalnP-based light-emitting diodes with an AuBe-diffused metal layer. It was also found that the 20 mA forward voltages measured from LEDs with Device A, Device B, Device C and Device D were 1.97, 1.96, 1.95 and 2.66 V and the light output powers were 4.2, 5.7, 6.0 and 6.3 mW, respectively. View full abstract»

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  • Frequency-Varying Spectral Shear Interferometry for Characterization of Extremely Short Attosecond Pulses

    Page(s): 810 - 818
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (697 KB) |  | HTML iconHTML  

    We theoretically investigate the complete amplitude and phase characterization of the isolated attosecond extreme ultraviolet (XUV) electric field by the spectral phase interferometry technique. Spectral shear needed for reconstruction of the spectral phase of the XUV pulse is prepared by modulating the driving optical pulse into two with different central wavelengths. We find that the spectral shear between the XUV pulses is almost linearly variable with the frequency, thus the phase reconstruction algorithm is modified by a non-uniformly sampled step concatenation. Numerical simulation using the harmonic spectrum and phase obtained from the saddle point analysis based on the widely used Lewenstein model indicates that this novel method is capable of measuring extremely short attosecond XUV pulses with several advantages owing to the all-optical apparatus: high efficiency and high time resolution, possibility of single-shot measurement, which provides a beneficial improvement to the current complicated photoelectron spectroscopic technique. We suggest that such a method is easy to implement, and propose a feasible experimental arrangement. View full abstract»

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  • Optimized Quantum–Well Semiconductor Optical Amplifier for RZ-DPSK Signal Regeneration

    Page(s): 819 - 826
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (940 KB) |  | HTML iconHTML  

    In this paper, we present an optimized quantum-well (QW)-semiconductor optical amplifier (SOA) which is capable of regenerating phase-modulated signals, such as return-to-zero differential-phase-shift keying (RZ-DPSK) signal. Based on the optimized QW SOA, the amplitude fluctuations are suppressed while the phase information is preserved. The essential mechanism of the optimized QW SOA is the low linewidth enhancement factor (α-factor), which can be obtained by means of structural optimization. Based on the numerical model, the power fluctuations can be suppressed from 4.26 mW (33% of input peak power) to 1.59 mW (13% of output peak power) at 40 Gb/s. The average phase noise induced by SOA is as small as 50. Furthermore, the DPSK signal regeneration scheme based on a single QW SOA is quite simple and stable. View full abstract»

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  • Modeling the Dynamic Response of an Optically-Injected Nanostructure Diode Laser

    Page(s): 827 - 833
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (917 KB) |  | HTML iconHTML  

    We reformulate a dimensionless approach to evaluate the operational dynamics of an optically injected nanostructure laser as a function of the injection strength and the detuning frequency to account for the large nonlinear gain component associated with nanostructure lasers through the nonlinear carrier relaxation rate and gain compression coefficient. The large nonlinear carrier relaxation rate and gain compression coefficient are shown to impact the level of stability numerically predicted in the optically injected laser at low injected power levels. The numerical model is verified experimentally by optically injecting a quantum-dash Fabry-Perot laser with an operating wavelength of approximately 1550 nm. The quantum-dash laser's large damping rate, gain compression coefficient, and sufficiently small linewidth enhancement factor are observed to inhibit period-doubling and chaotic operation under zero frequency-detuning conditions. The inclusion of the nonlinear carrier relaxation rate in the simulation is shown to greatly enhance the agreement between the numerical predictions and the experimentally observed dynamics. View full abstract»

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  • Difference Frequency Generation by Quasi-Phase Matching in Periodically Intermixed Semiconductor Superlattice Waveguides

    Page(s): 834 - 840
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    Wavelength conversion by difference frequency generation is demonstrated in domain-disordered quasi-phase-matched waveguides. The waveguide structure consisted of a GaAs/AlGaAs superlattice core that was periodically intermixed by ion implantation. For quasi-phase-matching periods of 3.0-3.8 μm, degeneracy pump wavelengths were found by second-harmonic generation experiments for fundamental wavelengths between 1520 and 1620 nm in both type-I and type-II configurations. In the difference frequency generation experiments, output powers up to 8.7 nW were generated for the type-I phase matching interaction and 1.9 nW for the type-II interaction. The conversion bandwidth was measured to be over 100 nm covering the C, L, and U optical communications bands, which agrees with predictions. View full abstract»

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  • Single Photon Detectors for Ultra Low Voltage Time-Resolved Emission Measurements

    Page(s): 841 - 848
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    Using time-resolved emission to measure electrical signals inside very-large-scale integration complementary metal-oxide-semiconductor circuits in a non-invasive fashion is a very powerful technique. However, node scaling and the related supply voltage reduction have created significant challenges. In this paper, we investigate the limits of established and prototype single photon detectors for future low voltage applications. In particular the performance of a state of the art InGaAs single photon avalanche photodiode and a superconducting single photon detector are reported and compared for low voltage applications using test vehicles fabricated in IBM 65 nm silicon on insulator technologies. View full abstract»

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  • Modeling the Effects of Interface Traps on the Static and Dynamic Characteristics of Ge/Si Avalanche Photodiodes

    Page(s): 849 - 857
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    The influence of interface donor and acceptor traps on the static and dynamic behavior of Ge/Si separate absorption, charge, and multiplication avalanche photodiodes (APDs) is modeled. The effects of different trap types, densities, and carrier capture cross sections on the dark current level, breakdown voltage, dc gain, and electric field profile, as well as on the frequency response and gain-bandwidth product of the device, are investigated for the first time. Our results show that the interface traps significantly increase the dark current and reduce the gain from 290 to less than 10. We also show that the acceptor traps reduce the APD bandwidth considerably to 0.5 GHz whereas the donor traps increase the bandwidth to around 10 GHz. View full abstract»

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  • Avalanche Multiplication and Excess Noise in InAs Electron Avalanche Photodiodes at 77 K

    Page(s): 858 - 864
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    The findings of a study of impact ionization, avalanche multiplication and excess noise in InAs avalanche photodiodes at 77 K are reported. It is shown that hole impact ionization is negligible in practical devices which continue to operate as electron avalanche photodiodes, as they do at room temperature. A new electron ionization coefficient capable of modeling multiplication at 77 K is presented and it is shown that significant multiplication can be achieved in practical devices without excessive tunneling currents. The characteristic changes observed between room temperature and 77 K are discussed. This paper helps to demonstrate the potential for practical InAs electron avalanche photodiodes, operating cooled. View full abstract»

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  • Passively Modelocked Laser With Tunable Pulse Repetition Frequency in a Semiconductor Optical Amplifier

    Page(s): 865 - 869
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (339 KB) |  | HTML iconHTML  

    We present the experimental demonstration of a pulse repetition frequency tunable passively mode-locked laser using semiconductor optical amplifier as the gain medium. The laser is designed for the 1550-nm telecommunication applications. The mode-locking mechanism is explained in terms of normal mode splitting of the continuous-wave spontaneous emission signal from the semiconductor optical amplifier. The splitting arises from the coupling between a quantum cavity, represented by the semiconductor gain medium, and an optical cavity comprised of a high-birefringence fiber in line with a Faraday mirror. Experimental results are presented for pulse repetition frequency tunability ranging between 93 and 1400 MHz, as well as for the pulse width which is measured to be 343 ps. These results are shown to compare favorably with theoretical calculations. View full abstract»

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  • Optical Gain in GaInNAs and GaInNAsSb Quantum Wells

    Page(s): 870 - 877
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    We have measured the absorption, gain and spontaneous emission spectra of GalnNAsSb (3.3%N), GalnNAs (0.5%N) and GalnAs quantum well structures to compare their merits as laser gain media. The parameters describing the relations between peak gain and current provide only limited insight. From the analysis of absorption spectra we have determined the intrinsic properties of the structures, represented by the product [reduced density of states × matrix element × overlap integral], taking account of differences in operating wavelength, well width and confinement. We find only a small variation in this product across the samples. The GalnNAsSb structure has a low radiative recombination current due in part to its low photon energy and also to differences in conduction and valence band densities of states and less inhomogeneous broadening relative to GalnNAs. We speculate that Sb brings benefits as a surfactant producing more homogeneous wells so Sb may also be beneficial in structures at shorter wavelength. However, there is a large non radiative current in GalnNAsSb and achieving further reductions in the non-radiative current is the major challenge in taking advantage of the good gain potential of this system. View full abstract»

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  • Modeling of Mid-Infrared Quantum Cascade Laser by Means of Nonequilibrium Green's Functions

    Page(s): 878 - 885
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB) |  | HTML iconHTML  

    Nonequilibrium Green's function (NEGF) calculations of mid-infrared quantum cascade laser (QCL) that preserve real-space basis have been performed. The approach developed in this paper relies on two improvements introduced to nonequilibrium Green's functions/Poisson computational scheme. First, the boundaries of single laser stage were carefully designed as to maintain its periodicity with the whole quantum cascade structure. Second, the NEGF/Poisson solver was equipped with several controlling features that enable the restoration of convergence of the method for quite complex structures with many resonances and boundary conditions for Poisson equation set inside the structure. With this simulation tool, calculations for an anticrossed diagonal design of mid-infrared QCL have been performed. Results agree with experimental data (threshold current of ~4.2 kA/cm2 at material gain of ~70/cm) and the current understanding of carrier transport in such devices. View full abstract»

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  • Special issue of the IEEE Journal of Quantum Electronics on Optoelectronic Device Integration

    Page(s): 886
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  • Special Issue of the IEEE Journal of Quantum Electronics on Plasma Photonics: Laser, Displays and Electronic Devices

    Page(s): 887
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  • IEEE Foundation [advertisement]

    Page(s): 888
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  • IEEE Journal of Quantum Electronics information for authors

    Page(s): C3
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  • Blank page [back cover]

    Page(s): C4
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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