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Quantum Electronics, IEEE Journal of

Issue 10 • Date Oct. 2005

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Displaying Results 1 - 22 of 22
  • Table of contents

    Page(s): c1 - c4
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  • IEEE Journal of Quantum Electronics publication information

    Page(s): c2
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  • Spatial nonuniformity of 4H-SiC avalanche photodiodes at high gain

    Page(s): 1213 - 1216
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB) |  | HTML iconHTML  

    We report spatial nonuniformity of responsivity of 4H-SiC avalanche photodiodes at high gain (M > 1000) that results from variation in the doping density. Two-dimensional raster scans show a steady decline laterally across the device. The direction in which the spatial response decreases is the same as that of increasing breakdown voltage on the wafer. View full abstract»

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  • Microscopic evaluation of spontaneous emission- and Auger-processes in semiconductor lasers

    Page(s): 1217 - 1226
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    A fully microscopic approach is used to compute the losses in semiconductor lasers due to spontaneous emission and Auger recombination. The model is based on the semiconductor-Bloch equations and generalized quantum-Boltzmann type scattering equations in the second Born-Markov approximation. As input the theory only needs the structural layout and fundamental bulk-bandstructure parameters. It is demonstrated that such a comprehensive model that calculates gain/absorption, spontaneous emission and Auger processes on the same microscopic level can reliably predict these usually dominant loss processes. Examples of the results are compared to measurements on lasers in the 1.3-1.5 μm range demonstrating very good agreement without empirical fitting. View full abstract»

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  • Electromagnetically induced distributed feedback intersubband lasers

    Page(s): 1227 - 1234
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    We propose a method to coherently generate uniform and phase-shifted complex-coupled (CC) semiconductor distributed feedback (DFB) lasers based on intersubband transitions in n-doped quantum-well structures. This is done by utilizing infrared-induced coherent optical processes in these structures including resonant enhancement of refractive index of the conduction intersubband transitions and generation of laser-induced transparency and gain without inversion. We show that these coherent phenomena can generate electromagnetically induced gratings where the index and gain/loss perturbations and their relative phases can be manipulated using an infrared laser beam. This allows us to coherently control optical feedback in a waveguide structure, switching from a case where there is no feedback in the absence of the infrared laser to the case where different types of CC optical feedbacks are generated as this field is properly adjusted. These include generation of gain and index perturbations (partly gain-coupled DFB laser), pure index corrugation (index-coupled DFB laser), and loss and index perturbations (loss-coupled DFB laser). We study these feedback mechanisms in the cases where the optically induced gratings are uniform along the cavity or have a π/2 phase shift. We discuss mode characteristics of such electromagnetically induced DFB intersubband lasers and find out how here the gain- and index-coupled DFB lasers are associated, respectively, with gain without inversion and laser-induced transparency in the conduction intersubband transitions of quantum-well structures. View full abstract»

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  • Measurement of the working parameters of an air-post vertical-cavity surface-emitting laser

    Page(s): 1235 - 1243
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    We present a complete experimental evaluation of the effective parameters necessary to describe the dynamical behavior of an air-post vertical-cavity surface-emitting lasers, on the basis of theoretical equations which are also derived in this paper. The experimental investigation is composed of several steps, including power versus current measurement, noise spectrum analysis, linewidth evaluation. The complete set of parameters derived, in particular the linewidth-enhancement factor and the spontaneous emission factor, is particularly important for accurate comparisons of theoretical models on the laser dynamics with experiments. View full abstract»

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  • Modeling ultrashort field dynamics in surface emitting lasers by using finite-difference time-domain method

    Page(s): 1244 - 1252
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    An approach based on the finite-difference time-domain (FDTD) method is developed for simulating the dynamics of vertical-cavity surface-emitting lasers (VCSELs). The material response is incorporated in our FDTD algorithm by the effective semiconductor Bloch equations, and its effects are accounted for through a resonant polarization term in the Maxwell's equations. Moreover, nonlinear gain saturation is incorporated through a gain suppression factor in the equation governing the dynamics of the resonant polarization. This approach is verified by modeling a λ-cavity VCSEL, with a multiple quantum-well (MQW) gain region; the corresponding continuous-wave operation is obtained at the expected wavelength. The dynamics of ultrashort pulses generated by a monolithic passively mode-locked one-dimensional VCSEL with a MQW gain region and a single QW saturable absorber are studied and it is demonstrated that a stable mode-locked pulse train can be generated. It is also demonstrated that with our FDTD approach subcycle temporal precision can be achieved. The need for this fine temporal resolution is established by investigating pulse propagation through the semiconductor saturable absorber. Fine features of the spatial profile of the mode-locked pulses are also examined within this approach. This knowledge of the fine spatial features is then used for lowering the current threshold through gain structure optimization. Various approaches for the reduction of the total simulation time are also discussed. View full abstract»

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  • Non-Markovian gain and luminescence of an InGaN-AlInGaN quantum-well with many-body effects

    Page(s): 1253 - 1259
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    The optical gain and the luminescence of an InGaN quantum well with quaternary AlInGaN barriers is studied theoretically. We calculated the non-Markovian optical gain and the luminescence for the strained-layer wurtzite quantum well taking into account of many-body effects. It is predicted that both optical gain and luminescence are enhanced significantly when aluminum and indium are introduced into the quaternary barrier composition. Adding the aluminum to the barrier will increase of the confinement potentials for electrons and holes, while the indium will reduce the biaxial strain, which in turn reduces the internal field caused by spontaneous polarization and piezoelectric effects. View full abstract»

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  • Two-wave competition in ultralong semiconductor optical amplifiers

    Page(s): 1260 - 1267
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    The copropagation of two waves in an ultralong semiconductor optical amplifier (SOA) is considered in theory and experiment. One wave is a modulated signal, whereas the other one is unmodulated (continuous wave). The theory bases on a comprehensive traveling-wave model and predicts an exponential improvement of the signal extinction ratio (ER) of the modulated signal, caused by the presence of the unmodulated signal. Conditions for achieving this two-wave competition (TWC) effect are as follows. The SOA is operated under saturation, both waves are copolarized, they have comparable gain and their spectral correlation is between certain limits. The TWC effect is due to nondegenerate four-wave mixing (FWM) in the saturated part of a long SOA and is expected to have a high-speed potential. In order to check the theoretical predictions, 4-mm-long SOAs are developed and experimentally investigated under the given conditions. The measured ER improves by 1.3 dB for a 5-GHz sinusoidal signal, which compares well with the 2 dB theoretically predicted for this configuration. FWM is identified also experimentally as the basic mechanism. Variation of wavelength detuning, pump current, modulation frequency and ER of the injected signal are used to determine optimum conditions for the given device. View full abstract»

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  • Acceleration of gain recovery and dynamics of electrons in QD-SOA

    Page(s): 1268 - 1273
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    We propose a new method for reducing the patterning effect in quantum-dot semiconductor optical amplifier (QD-SOA) by using an additional light beam. A detailed theoretical analysis of the carrier dynamics in QD-SOA is presented. It is shown that the increase of the bias current only partially improves the QD-SOA temporal behavior. The additional light beam drastically reduces the patterning effect. View full abstract»

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  • 300-W cryogenically cooled Yb:YAG laser

    Page(s): 1274 - 1277
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    Thermooptic effects often limit the power and beam quality of bulk-solid-state lasers. Cryogenically cooled (∼100 K) Yb:YAG lasers have been previously demonstrated to have relatively low thermooptic effects and high efficiency due to improved material properties at low temperatures. In this work, >300-W average power with M2∼1.2 and 64% optical-optical efficiency has been demonstrated from an end-pumped-rod geometry power oscillator. To our knowledge, this is the highest average power to date from a cryogenically cooled Yb:YAG laser. View full abstract»

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  • Q-switched rate equations for diode side-pumped slab and zigzag slab lasers including Gaussian beam shapes

    Page(s): 1278 - 1284
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    A set of rate equations accounting for the transverse spatial distributions of both the laser mode and inversion density is developed for side-pumped Q-switched oscillators. The equations can be reduced to a simple form by assuming a Gaussian laser mode, a one-dimensional Gaussian pump beam and a few additional basic assumptions, allowing for rapid numerical solution. The derived spatial rate equations are then used to model an experimentally well-characterized Nd+3:YAG zigzag slab laser to demonstrate their simplicity and accuracy in predicting oscillator performance. View full abstract»

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  • Repetition-rate-multiplication in actively mode-locking fiber laser by using phase modulated fiber loop mirror

    Page(s): 1285 - 1292
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB) |  | HTML iconHTML  

    We demonstrate a simple scheme to multiply the repetition rate in an actively mode-locking fiber laser by using a phase modulated optical fiber loop mirror (PMOLM). The PMOLM can convert phase modulation to amplitude modulation at double the modulation frequency. In principle, it is easy to double the repetition rate. However, the PMOLM also induces residual chirp which can disable this method in some cases. Numerical simulation shows that the best results can be obtained when the intracavity dispersion is negative and the modulation frequency is an odd harmonic of half of the cavity fundamental frequency. This agrees with the experimental results, in which an 80-GHz 1.74-ps transform limited pulse was obtained. By using rational harmonic modulation which requires detuning the modulation frequency and adjusting the modulation index, the repetition rate can be increased by three or four times. View full abstract»

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  • Form birefringence phase matching in multilayer semiconductor waveguides: tuning and tolerances

    Page(s): 1293 - 1302
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    GaAs-Alox waveguide structures for parametric processes are analyzed in detail. The geometric tolerances of the structure are numerically calculated with reference to its parametric tuning. Finally, the tunability of GaAs-Alox based parametric devices versus temperature is investigated. View full abstract»

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  • Low switching threshold using nonlinearities in stopband-tapered waveguide Bragg gratings

    Page(s): 1303 - 1308
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    We numerically study the nonlinear switching characteristics in a waveguide grating with a linearly tapered stopband. This type of design shows promising results in decreasing the threshold switching power, while simultaneously preserving a significant extinction ratio. We find that the switching threshold changes linearly with the tapering coefficient. The physical explanation for these phenomena is discussed. Potential applications for this type of device include all-optical switches and isolators. View full abstract»

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  • Studies of CW laser oscillation on the 1315-nm transition of atomic iodine pumped by O2(a1Δ) produced in an electric discharge

    Page(s): 1309 - 1318
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    In this paper, we report on studies of a continuous-wave laser at 1315 nm on the I(2P12/)→I(2P32/) transition of atomic iodine where the O2(a1Δ) used to pump the iodine was produced by a radio frequency excited electric discharge. The electric discharge was sustained in He-O2 and Ar-O2 gas mixtures upstream of a supersonic cavity which is employed to lower the temperature of the continuous gas flow and shift the equilibrium of atomic iodine in favor of the I(2P12/) state. The results of experimental studies for several different flow conditions, discharge arrangements, and mirror sets are presented. The highest laser output power obtained in these experiments was 520 mW in a stable cavity composed of two 99.995% reflective mirrors. View full abstract»

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  • Measurement of thermooptic coefficients dnE/dT and dnO/dT of AgGaS2 at 308 and 97 K

    Page(s): 1319 - 1322
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    Thermooptic coefficients (dnE/dT and dnO/dT) of AgGaS2 have been measured at temperatures of ∼308 and 97 K, using temperature-induced shift in the frequency of the interference fringes in the Fourier transform infrared (FTIR) transmittance spectrum of a 2-mm-thick etalon. Values of dnE/dT and dnO/dT are reported for the spectral regime from 12.4 μm to 1.06 μm; the subscripts E and O refer to extraordinary and ordinary rays, respectively. Our values of dnE/dT and dnO/dT at 308 K are significantly lower (∼1/3) than those reported previously. View full abstract»

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  • Energy transfer through laterally confined Bragg mirrors and its impact on pillar microcavities

    Page(s): 1323 - 1329
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    It has been recently reported that the electromagnetic properties of pillar microcavities present an intricate and unexpected behavior for diameters smaller than the resonant wavelength. For instance, the micropillar quality factors can reach values well in excess of the quality factor of the reference planar cavity. In this work, we explain the reason for this behavior and provide an in-depth analysis of the energy-transfer mechanism through distributed Bragg mirror with finite lengths. We show that, in addition to a classical backscattering via the evanescent fundamental Bloch mode, the reflection is also mediated by another Bloch mode, which propagates in the mirror without leakage. This Bloch mode plays a central role in the electromagnetic properties of pillar microcavities and has to be taken into account for the optimization of the micropillar parameters. View full abstract»

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  • IEEE/OSA Journal of Display Technology

    Page(s): 1330
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  • The 18th Annual Meeting of the IEEE Lasers and Electro-Optics Society

    Page(s): 1331
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  • The 4th IEEE Conference on Sensors

    Page(s): 1332
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    Freely Available from IEEE
  • IEEE Journal of Quantum Electronics information for authors

    Page(s): c3
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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