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Quantum Electronics, IEEE Journal of

Issue 2 • Date Feb. 2010

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Displaying Results 1 - 25 of 27
  • [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): 138 - 139
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  • Dynamics of Broad-Area Semiconductor Lasers With Short Optical Feedback

    Page(s): 140 - 149
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    The dynamics of filamentations in broad-area semiconductor lasers with short optical feedback were numerically studied. Regular pulse packages similar to those observed in narrow-stripe edge-emitting semiconductor lasers were found as the feedback reflectivity is increased. However, the regular pulse packages consisted of a periodic envelope of the external cavity frequency and fine pulse trains of periodic filaments, which is different from the regular pulse packages observed in narrow-stripe edge-emitting semiconductor lasers. From the analysis for spatio-temporal near-field patterns, we found periodic undulations of the spatial and temporal filament sizes as the external mirror reflectivity was changed. We also investigated filtered optical feedback, where a part of the emitted beam is fed back into the laser cavity. The time-averaged near-field pattern was found to have a strong dependence on the feedback level in the case of spatial filtered optical feedback. View full abstract»

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  • Investigations of Repetition Rate Stability of a Mode-Locked Quantum Dot Semiconductor Laser in an Auxiliary Optical Fiber Cavity

    Page(s): 150 - 157
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    We have investigated experimentally the pulse train (mode beating) stability of a monolithic mode-locked multi-section quantum-dot laser with an added passive auxiliary optical fiber cavity. Addition of the weakly coupled (¿ -24 dB) cavity reduces the current-induced shift d¿/dI of the principal peak in the RF spectrum (the effective pulse repetition frequency) by more than an order of magnitude, from -39.5 to -2.3 kHz/mA. The rms timing jitter of the pulse train is simultaneously reduced from 1.4 to 0.9 ps. View full abstract»

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  • Analysis of Relaxation Oscillations and Gain Switching of Unidirectional Erbium-Doped Waveguide Ring Lasers

    Page(s): 158 - 163
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    Relaxation oscillations and gain switching of erbium-doped waveguide ring lasers (EDWRLs) are studied using numerical simulations based on time-dependent rate-propagation equations. The counter-directional wave suppression is analyzed for different waveguide ring cavity configurations and pumping schemes. It is shown that the counter-directional wave suppression in unidirectional EDWRLs undergoes relaxation oscillations synchronously with oscillating power. It is also shown that the suppression in the first spike is maximal, so the gain switching technique provides the most favorable conditions for unidirectional lasing. Furthermore, for the one-end-pumped gain-switched EDWRL, highly unidirectional operation is possible with no intracavity elements included. In this case the counter-directional wave suppression considerably exceeds its steady-state value. The gain-switched suppression caused by intracavity elements is close to the steady-state value. View full abstract»

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  • High Conversion Efficiency InP/InGaAs Strained Quantum Well Infrared Photodetector Focal Plane Array With 9.7 \mu m Cut-Off for High-Speed Thermal Imaging

    Page(s): 164 - 168
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    InP/InGaAs material system is an alternative to AlGaAs/GaAs for long wavelength quantum well infrared photodetectors (QWIPs). We demonstrate a large format (640 ?? 512) QWIP focal plane array (FPA) constructed with the strained InP/InGaAs material system. The strain introduced to the structure through utilization of In0.48Ga0.52As (instead of In0.53Ga0.47As ) as the quantum well material shifts the cut-off wavelength from ˜8.5 to 9.7 μm. The FPA fabricated with the 40-well epilayer structure yields a peak quantum efficiency as high as 12% with a broad spectral response (Δλ/p=17%). The peak responsivity of the FPA pixels is 1.4 A/W corresponding to 20% conversion efficiency in the bias region where the detectivity is reasonably high (2.6 ?? 1010 cm Hz1/2/W, f/1.5, 65 K). The FPA providing a background limited performance temperature higher than 65 K (f/1.5) satisfies the requirements of most low integration time/low background applications where AlGaAs/GaAs QWIPs suffer from read-out circuit noise limited sensitivity due to lower conversion efficiencies. Noise equivalent temperature differences of the FPA are as low as 19 and 40 mK with integration times as short as 1.8 ms and 430 μs (f/1.5, 65 K). View full abstract»

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  • Decay Dynamics of Excited Nd ^{+3} Ions in Nd:YVO _{4} Following Weak Excitation

    Page(s): 169 - 181
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    Decay dynamics of the upper-laser energy level of Nd:YVO4 are re-evaluated. In order to reduce the effects of re-absorption, comparative measurements among crushed samples with different doping concentrations were conducted. The magnitude of re-absorption was estimated experimentally by comparing the relative intensity of the emitted fluorescence spectra at different wavelengths, and estimated theoretically by employing a simplified model. The temporal decay dynamics are found to be non-exponential and the associated rate parameters are presented. The room temperature intrinsic life time value of the 4F3/2 energy level is found to be significantly shorter than the value accepted today. View full abstract»

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  • Absorption, Gain, and Laser Action in Bismuth-Doped Aluminosilicate Optical Fibers

    Page(s): 182 - 190
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    In this study, bismuth-doped fiber lasers operating at the wavelength of 1179 nm with an optical efficiency of up to 28% are realized. The fiber gain upon 1-¿m pumping declines, while the unsaturable absorption increases with increasing the small-signal absorption. We conclude that up-conversion and excited-state absorption are responsible for limiting the efficiency of such lasers. View full abstract»

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  • An Optical Replicator for Single-Shot Measurements at 10 GHz With a Dynamic Range of 1800:1

    Page(s): 191 - 196
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    High-dynamic-range, single-shot pulse shapes were measured by temporally stacking pulses in a passive, fiber-optic network. The 256 replicas were combined to produce optical shapes with a bandwidth of 10 GHz and a dynamic range of 1800:1. The high fidelity of this system enabled the characterization of arbitrary electrical pulses that were used to shape the optical pulse via an electro-optic modulator with a reduced dynamic range of about 60:1. View full abstract»

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  • Polarization Properties of Columnar Quantum Dots: Effects of Aspect Ratio and Compositional Contrast

    Page(s): 197 - 204
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    We report a systematic theoretical and experimental investigation of the polarization properties of columnar quantum dots (CQDs) with extremely large aspect ratio and high compositional contrast. A strong variation of the polarization of the dominant interband transitions as a function of the CQD composition and aspect ratio is predicted by the theory and observed experimentally. In optimized InAs CQDs grown on GaAs, dominant emission and lasing is obtained in the transverse-magnetic polarization, which shows the potential of this approach for polarization-independent amplifiers on GaAs. View full abstract»

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  • Selection of Extreme Events Generated in Raman Fiber Amplifiers Through Spectral Offset Filtering

    Page(s): 205 - 213
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    In this work, we discuss the emergence of rare and intense events in a Raman fiber amplifier. The temporal and spectral evolutions of continuous and pulsed signals are investigated, and approaches based on spectral slicing of the broadened spectra are proposed in order to isolate the rarest events. Numerical simulations are confirmed by experimental results. View full abstract»

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  • Effects of Zn Doped Mesa Sidewall on Gain Enhanced InGaAs/InP Heterobipolar Phototransistor

    Page(s): 214 - 219
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    The excellent detectability of the gain enhanced InGaAs/InP heterobipolar phototransistor (GE-HPT) is demonstrated and attributed to a reduction in the reverse leakage current at the base-collector junction and the enhancement of current gain at the emitter-base junction achieved by using a current blocking structure with a Zn doped mesa sidewall. The common emitter grounded current gain agrees well with the photo-conversion efficiency of several tens of thousands of A/W at incident optical powers in the hundred nanowatt to sub-picowatt range over several orders of magnitude. The deep mesa structure in the GE-HPT is also effective in ensuring superior isolation of better than 25 dB between adjacent arrays. View full abstract»

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  • Dynamics of Optically-Injected Semiconductor Lasers Using the Travelling-Wave Approach

    Page(s): 220 - 227
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    The dynamics of optically-injected semiconductor lasers are of great practical interest for various applications such as chaotic signal transmission. For the first time, a method is presented to obtain a complete picture of the dynamics for optically-injected systems simulated with the travelling-wave model by investigating their trajectories. The method uses the distribution of intersection points of the trajectory on a Poincare plane to distinguish between different dynamical states of the system. It is then applied to obtain stability maps for the reflected and transmitted light of three quarter-wave-shifted distributed-feedback lasers with different Bragg coupling coefficients and it is shown that, firstly, the dynamics are different for the reflected and transmitted light and, secondly, the locking bandwidth for the case with lower Bragg coupling coefficient is significantly increased. Both findings are in agreement with published results obtained by a different analysis. The obtained stability maps are then applied to find three points inside each locking region for which the longitudinal power and carrier distributions along the cavity are displayed. These distributions are compared with the solitary laser and the relation between the Bragg coupling coefficient and its influence on the shape of the power and carrier distributions is shown. View full abstract»

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  • Design of a GaN White Light-Emitting Diode Through Envelope Function Analysis

    Page(s): 228 - 237
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    In this paper, we present an envelope function analysis technique for the design of the emission spectra of a white quantum-well light-emitting diode (QWLED). The nanometric heterostructure that we are dealing with is a multiple QW, consisting of periods of three single QWs with various well thicknesses. With the aid of 6 × 6 Luttinger Hamiltonian, we employ the combination of two methods, k·p perturbation and the transfer matrix method, to acquire the electron and hole wave functions numerically. The envelope function approximation was considered to obtain these wave functions for a special basis set. While adjacent valence sub-bands have been determined approximately, the conduction bands are approximated as parabolic. The effect of Stokes shift has also been taken into account. The dipole moment matrix elements for interband atomic transitions are evaluated via the correlation between the electron and hole envelope functions, for both orthogonal polarizations, thus simplifying the calculation of the photoluminescence intensity. Spatial variations in the hole/electron wave functions have been examined with the introduction of piezoelectric and spontaneous polarization internal fields. We theoretically establish the possibility of a highly efficient InGaN red emitter, resulting in a uniform luminescence in red, green, and blue emissions from a white light emitting diode by adjusting the material composition, internal field, and well thickness. View full abstract»

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  • Design Strategies for InGaN-Based Green Lasers

    Page(s): 238 - 245
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    A design parameter subspace is explored to suggest epitaxial layer structures which maximize gain spectral density at a target wavelength for green In¿Ga1-¿N-based single quantum well active regions. The dependence of the fundamental optical transition energy on the thickness and composition of barriers and wells is discussed, and the sensitivity of gain spectral density to design parameters, including the choice of buffer layer material, is investigated. View full abstract»

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  • Characteristics of an AlGaInP-Based Light Emitting Diode With an Indium-Tin-Oxide (ITO) Direct Ohmic Contact Structure

    Page(s): 246 - 252
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    An AlGaInP multi-quantum-well (MQW) light-emitting diode (LED) with a direct Ohmic contact structure, formed by an indium-tin-oxide (ITO) transparent film and AuBe diffused thin layer, is fabricated and studied. By the deposition of an AuBe metallic thin layer on the surface of Mg-doped GaP window layer, followed by a thermal activation process, a direct Ohmic contact between ITO and p-GaP layers can be obtained. Experimentally, under an injection current of 20 mA, a dynamic resistance of 5.7 ¿ and a forward voltage of 1.91 V, are obtained. In addition, a higher external quantum efficiency of 9.7% and a larger maximum light output power of 26.6 mW are found for the studied LED. As compared with the conventional LED without this structure, the external quantum efficiency of the studied device is increased by 26% under the injection current of 100 mA. This is mainly attributed to the reduced series resistance resulted from the relatively uniform distribution of AuBe atoms near the GaP layer surface and the effective current spreading ability by the use of ITO film. Moreover, the life behavior is not degraded by using this AuBe diffused layer for the studied LED under a 20 mA operation condition. View full abstract»

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  • Optimised Message Extraction in Laser Diode Based Optical Chaos Communications

    Page(s): 253 - 257
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    Synchronization quality and message extraction using chaotic laser diode as transmitter-receiver pairs has been experimentally studied. The experimental results demonstrate that the conditions for maximum signal to noise ratio (SNR) of the extracted message are not identical to those for achieving maximum chaos synchronization quality. It is also shown that synchronization quality and message extraction not only depend on having well-matched lasers as transmitter and receiver, but also depend on the roles of the laser diodes. View full abstract»

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  • Private Message Transmission by Common Driving of Two Chaotic Lasers

    Page(s): 258 - 264
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    In this paper, we numerically demonstrate private data transmission using twin semiconductor lasers in which chaotic dynamics and synchronization are achieved by optical injection into the laser pair of a common, chaotic driving-signal, generated by a third laser subject to delayed optical feedback. This laser is selected with different parameters with respect to the twin pair, so that the emissions of the synchronized, matched lasers are highly correlated, whereas their correlation with the driver is low. The digital message modulates the emission of the transmitter, as in a standard CM scheme. Message recovery is then obtained by subtracting, from the transmitted chaos-masked message, the chaos, locally generated by the synchronized receiver laser. Simulations have been performed with the Lang-Kobayashi model, keeping into account both laser and photodetector noise. Private transmission has been demonstrated by investigating the effect of the parameter mismatch, between transmitter and receiver, on synchronization and message recovery. View full abstract»

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  • UV Electroluminescence and Structure of n-ZnO/p-GaN Heterojunction LEDs Grown by Atomic Layer Deposition

    Page(s): 265 - 271
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    Atomic layer deposition technique and subsequent rapid thermal annealing (RTA) were implemented to grow high-quality ZnO epilayers for the fabrication of n-ZnO/p-GaN heterojunction LEDs. The X-ray diffraction measurement reveals that the ZnO epilayer has high crystallinity with c axis orientation. Transmission electron microscopy images present that the ZnO layer is a single crystal, including only a few survivals of threading dislocations, which were generated in the GaN layer deposited by metal-organic chemical vapor deposition on the c-Al2O3 substrate and most of which were eliminated at the n-ZnO/p-GaN interface. An interfacial layer 4-5 nm thick caused by the RTA treatment was observed between the n-ZnO and p-GaN layers. Room temperature UV electroluminescence (EL) at 391 nm from ZnO was achieved at a low injection current about 10 mA. It is concluded that the competition between the ELs from the n-ZnO and p-GaN (around 425 nm) may be ascribed to the ZnO/GaN interface states coupled with the differences between the n-ZnO and p-GaN in carrier concentration and light emission efficiency. View full abstract»

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  • The Performance of Acoustic-Optical Q -switched Mode-Locking 1.34 \mu m Nd:GdVO _{4} Laser

    Page(s): 272 - 276
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    A diode-end-pumped Q -switched mode-locking Nd:GdVO4 laser operating at 1.34 μm with an acousto-optical (AO) Q-switch in a compact V-type cavity was realized in our experiment for the first time. When the AO Q-switch repetition rate was 10 kHz, the maximum average output power of 750 mW and the pulse energy of 75 μ were obtained at the maximum incident pump power of 9 W. The mode-locking modulation depth of about 100% was obtained at certain pump power over the threshold. The mode-locked pulse inside in the Q-switched pulse had a repetition rate of 341 MHz, and its average pulsewidth was estimated to be about 350 ps. A developed rate equation model for the Q -switched and mode-locked lasers with an AO Q-switch were proposed by using the hyperbolic secant functional methods. The results of numerical calculations of the rate equations were in good agreement with the experimental results. View full abstract»

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  • High Peak Power, Passively Q -switched Microlaser for Ignition of Engines

    Page(s): 277 - 284
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    The compact (electric spark plug size), diode-pumped, passively Q-switched Nd:YAG/Cr4+:YAG microlaser was developed for ignition of engines. Output energy of 2.7 mJ per pulse and 11.7 mJ per four-pulse train with a pulsewidth of 600 ps and an M 2 value of 1.2 were obtained at a pump duration of 500 ¿s. The optical-to-optical conversion efficiency was 19%. Brightness of the microlaser was calculated as 0.3 PW/ sr-cm2 and optical power intensity was calculated as 5 TW/cm2 at the focal point of ignition. The enhanced combustion by the microlaser ignition was successfully demonstrated in a constant-volume chamber at room temperature and atmospheric pressure. The cross section area of a flame kernel generated by laser ignition is 3 times larger than that by a conventional spark plug at 6 ms after ignition in a stoichiometric mixture (A/F 15.2) of C 3H 8/air, even though ignition energy of the laser is 1/3 of that of the spark plug. Hundred percent ignition was successfully demonstrated in a lean mixture of A/F 17.2 by laser ignition, where electric spark plug ignition failed. View full abstract»

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  • Demonstration of Megapixel Dual-Band QWIP Focal Plane Array

    Page(s): 285 - 293
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    Quantum well infrared photodetectors (QWIPs) are well known for their stability, high pixel-pixel uniformity and high pixel operability which are quintessential parameters for large area imaging arrays. In this paper we report the first demonstration of the megapixel-simultaneously-readable and pixel-co-registered dual-band QWIP focal plane array (FPA). The dual-band QWIP device was developed by stacking two multi-quantum-well stacks tuned to absorb two different infrared wavelengths. The full width at half maximum (FWHM) of the midwave infrared (MWIR) band extends from 4.4-5.1 ¿m and FWHM of the long-wave infrared (LWIR) band extends from 7.8-8.8 ¿m. Dual-band QWIP detector arrays were hybridized with direct injection 30 ¿m pixel pitch megapixel dual-band simultaneously readable CMOS read out integrated circuits using the indium bump hybridization technique. The initial dual-band megapixel QWIP FPAs were cooled to 68 K operating temperature. The preliminary data taken from the first megapixel QWIP FPA has shown system NE¿T of 27 and 40 mK for MWIR and LWIR bands, respectively. View full abstract»

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  • Special issue on Green Photonics: Energy Efficiency in Quantum Electronics

    Page(s): 294
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  • Special issue on nanowires

    Page(s): 295
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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..

Full Aims & Scope

Meet Our Editors

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