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Quantum Electronics, IEEE Journal of

Issue 12 • Date Dec. 2005

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Displaying Results 1 - 25 of 27
  • Table of contents

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

    Page(s): c2
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  • Editorial

    Page(s): 1429
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  • High-power room temperature emission quantum cascade lasers at λ=9 μm

    Page(s): 1430 - 1438
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB) |  | HTML iconHTML  

    We present two different techniques for processing InP-based λ=9 μm quantum cascade lasers which improve the thermal dissipation in the device. The first process is based on hydrogen implantation creating an insulating layer to inject current selectively in one part of the active region. The second process uses a thick electroplated gold layer on the laser ridge to efficiently remove the heat produced in the active region. Each process is designed to improve heat evacuation leading to higher performances of the lasers and will be compared to a standard ridge structure from the same wafer. We give evidence that the process of proton implantation, efficient in GaAs based structures, is not directly applicable to InP based devices and we present a detailed analysis of the thermal properties of devices with an electroplated gold thick layer. With these lasers, an average power of 174 mW at a duty cycle of 40% has been measured at 10°C. View full abstract»

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  • Optical in-well pumping of a semiconductor disk laser with high optical efficiency

    Page(s): 1439 - 1449
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    Optical in-well pumping is shown to lead to highly efficient operation of semiconductor disk-lasers using resonant absorption or using external optics. Pump radiation absorption of 70% at 940 nm is demonstrated for a laser emitting around 980 nm. Laser output power was 1.9 W with slope efficiencies up to 35% based on the incident power. View full abstract»

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  • Tolerance of phase-locked VCSEL arrays to random and systematic parameter deviations among cavities

    Page(s): 1450 - 1460
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    Cavity parameter deviations from their nominal values affect phase-locking in vertical-cavity surface-emitting lasers (VCSEL) arrays. The phase-locking tolerance is studied analytically and numerically for both random as well as systematic parameter variations. Parameter-induced deviations among the cavity eigenfrequencies cause the dominant effect. For small externally imposed variations, self-regulated nonlinear frequency pulling among cavities overcomes original detuning and permits phase-locking. The root mean square (rms) tolerance threshold is derived by solving a quasi-random matrix eigenvalue under simplifying assumptions. Tolerance increases with intercavity coupling strength and decreases with the array size M. Systematic variations, such as thermal drifts, exhibit a lower tolerance decreasing as ∝1/M or faster, compared to random variations ∝1/√M. Theory results qualitatively agree with large size array simulations employing actively coupled rate equations. View full abstract»

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  • Polarization-preserved and polarization-rotated synchronization of chaotic vertical-cavity surface-emitting lasers

    Page(s): 1461 - 1467
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    The synchronization process in a vertical-cavity surface-emitting laser (VCSEL) based master-slave configuration, where the master laser has been destabilised by optical feedback from an external mirror, has been investigated. The dynamics of both VCSEL polarization modes have been modeled and used to study the chaos synchronization mechanism in both polarization preserved, and polarization rotated unidirectionally coupled master and slave configurations. Two types of synchronization have been identified in the polarization rotated case, one of which may afford an opportunity to effect multiplexed message encoding using orthogonal laser modes. View full abstract»

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  • Theoretical investigation of quantum-dot avalanche photodiodes for mid-infrared applications

    Page(s): 1468 - 1473
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    A novel midinfrared sensor, called the quantum-dot avalanche photodiode (QDAP), is proposed which is expected to have improved signal-to-noise ratio (SNR) in the presence of Johnson noise over its quantum-dot (QD) counterpart. In the QDAP, an intersubband QD detector is coupled with a thin, low-noise GaAs avalanche layer through a tunnel barrier. The avalanche layer provides the necessary photocurrent gain required to overcome Johnson noise and nearly achieve the dark-current-limited SNR of the QD detector. In the proposed three-terminal device, the applied biases of the QD-detector and the avalanche-photodiode sections of the QDAP are controlled separately. This feature permits the control of the QDs responsivity and dark current independently of the operating avalanche gain, thereby allowing the optimization of the avalanche multiplication factor to maximize the photocurrent's SNR. Notably, a heterojunction potential-barrier layer can also be utilized to further improve the SNR. For example, when the standard deviation of the Johnson noise is four times greater than the dark current, calculations show that the SNR enhancement offered by an avalanche multiplication factor of 5 results in relaxing the cooling requirement from 20 to 80 K. View full abstract»

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  • Negative and positive luminescence in midwavelength infrared InAs-GaSb superlattice photodiodes

    Page(s): 1474 - 1479
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    The quantum efficiency of negative and positive luminescence in binary type-II InAs-GaSb superlattice photodiodes has been investigated in the midinfrared spectral range around the 5-μm wavelength. The negative luminescence efficiency is nearly independent on temperature in the entire range from 220 to 325 K. For infrared diodes with a 2-μm absorbing layer, processed without anti-reflection coating, a negative luminescence efficiency of 45% is found, indicating very efficient minority carrier extraction. The temperature dependent measurements of the quantum efficiency of the positive luminescence enables for the determination of the capture cross section of the Shockley-Read-Hall centers involved in the competing nonradiative recombination. View full abstract»

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  • Bragg gratings based on long-range surface plasmon-polariton waveguides: comparison of theory and experiment

    Page(s): 1480 - 1491
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    Measured optical spectra are presented for a family of third-order uniform step-in-width Bragg gratings operating in the long-range surface plasmon-polariton mode supported by thin finite-width Au films in a homogeneous dielectric background. The spectra are compared quantitatively with theoretical predictions generated by a model proposed for the gratings. Physical measurements of critical features achieved on-wafer have been made and the results used in the theoretical model. The measured and modeled results are generally in good agreement. The largest reflectance measured among the set of gratings characterized is 47.4%, the bandwidths (full width at half maximum) measured range from 0.2 to 0.4 nm, and the measured Bragg wavelengths coincide to 1544.2 nm for all of the gratings. View full abstract»

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  • Spectral investigation of multimode fiber Bragg grating based external-cavity semiconductor lasers

    Page(s): 1492 - 1501
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    The output spectra of external-cavity semiconductor lasers (ECSLs) formed by using different antireflection (AR) coated laser diodes (LDs) with multimode fiber Bragg gratings (MMFBGs), are studied systematically. It is found that the side mode suppression ratio (SMSR) of the output spectra of ECSL is dependent on the relative position of the Bragg wavelength and the intracavity modes of the LD, and this effect is more apparent when the reflectivity of AR coating of LD is increased. Numerical simulations are provided to explain the experimental observations. Furthermore, the requirements of wavelength locking of ECSLs with MMFBGs are found to be different from those with single-mode fiber Bragg gratings (SMFBGs). The conditions of wavelength locking of the MMFBG-based ECSLs in terms of gain margin between the material gain peak and the gain corresponding to the selected Bragg wavelength, reflectivity of AR coating of LD and reflectivities of the Bragg wavelengths of MMFBG are comprehensively investigated, and compared with the experimental results. View full abstract»

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  • Efficient approximation to calculate time delay and dispersion in linearly chirped periodical microphotonic structures

    Page(s): 1502 - 1509
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB) |  | HTML iconHTML  

    The Bloch mode propagation through the chirped periodical structure is defined by its local dispersion relation. In a slowly varying structure its time delay is the integral of the local inverse group velocity along the propagation direction. The integration can be strongly simplified for linearly chirped structures if the assumption is made that the local dispersion relation is just a scaled and shifted version of the dispersion relation at the input. This assumption leads to exact solutions for the structures with locally uniaxial deformation and provides a good approximation for arbitrary structures with small chirps. The approach is demonstrated for high index contrast chirped Bragg mirrors and complicated photonic crystal waveguide structures, including coupled waveguides and a slow group velocity waveguide. View full abstract»

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  • Ytterbium laser with reduced thermal loading

    Page(s): 1510 - 1517
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    We report a novel design for a high-power ytterbium disk laser. This laser utilizes radial diode pumping of a back surface cooled active-mirror geometry. Wing absorption of the pump light at 0.99 μm allows efficient laser operation at 1.05 μm with a low quantum defect. Laser performance and thermal loading were characterized for a wide range of conditions. Optimized operation of the laser yielded 490 W in a quasi-continuous-wave mode. Electrical efficiency of the laser was found to be 9.4%, while heating of the laser disk was only 3.2% of the absorbed optical power. Fluorescence re-absorption is identified as the principal heat generation mechanism in this laser. A simplified extension to the conventional rate model is proposed for lasing in radiation-trapped systems. This model allows power flow calculations in a radiation-trapped laser system using a single parameter determined from fluorescence decay waveforms. The revised model agrees with heat load measurements. View full abstract»

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  • Analysis and suppression of Q-switching instabilities in mode-locked lasers-a control systems approach

    Page(s): 1518 - 1527
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB) |  | HTML iconHTML  

    We investigate the origin of Q-switching instabilities in a mode-locked laser from a control systems viewpoint. The laser is represented as a linear control system, and we consider active laser stabilization either by gain or by loss control as well as passive stabilization via inverse saturable absorption. Gain control stabilization compensates for low-pass filtering in the gain relaxation branch of the system, while control of intracavity losses directly counteracts the destabilizing effect of the saturable absorber. For both stabilization approaches, design rules are derived for controller gain and bandwidth, and their applicability to different laser systems is investigated. Our discussion is concluded with a control systems analysis of passive laser stabilization via inverse saturable absorption. The control systems representation makes the established methods of control theory available to active and passive laser stabilization. View full abstract»

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  • The generation and frequency measurement of short-wavelength far-infrared laser emissions

    Page(s): 1528 - 1532
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    A significantly improved three-laser heterodyne system has been assembled to generate and measure short-wavelength far-infrared (FIR) laser emissions. Over the past several years, this system has been used to discover fifty-five FIR laser emissions, ranging in wavelength from 26.3 to 185.0 μm. These emissions were generated by optically pumping a FIR cavity with a continuous-wave carbon dioxide laser in a X-V geometry when using either hydrazine or a methanol isotopologue as the FIR laser medium. Although heterodyne techniques can be used to measure the frequencies of these FIR laser emissions with fractional uncertainties of ±2×10-7, shortcomings in the previous system limited its effectiveness. Improvements made to the three-laser heterodyne system have resulted in an increase in the spectral range used to search for the beat between the known and unknown laser frequencies (an increase of up to 25 GHz) as well as an increase in the system's sensitivity (by up to a factor of 30), all without requiring the use of an additional microwave frequency source. With this improved system, the FIR laser frequencies for the recently discovered 53.9- and 90.0-μm laser emissions generated by optically pumped CH3OD have been measured. View full abstract»

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  • Serrodyne frequency translation of continuous optical signals using ultrawide-band electrical sawtooth waveforms

    Page(s): 1533 - 1539
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    Serrodyne frequency translation of continuous optical signals by ±1.28 GHz is reported, significantly exceeding the highest previously published serrodyne shifts. To achieve these shifts, an ultrawide-band high-power electrical sawtooth created by spectral modulation of dispersed optical pulses was used. Its amplification involved a novel predistortion technique to compensate for the gain and phase ripple in the amplifier bandwidth. View full abstract»

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  • Multiple quasi-phase-matched device using continuous phase modulation of χ(2) grating and its application to variable wavelength conversion

    Page(s): 1540 - 1547
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    We propose a new multiple quasi-phase-matched wavelength converter based on the continuous phase modulation of a χ(2) grating for use in variable wavelength conversion. A numerical study shows that the proposed device exhibits a high conversion efficiency, flexible design, and robust fabrication tolerance. A waveguide device fabricated by annealed proton exchange agrees well with the numerical design. Fine-tuning the device enabled us to demonstrate variable wavelength conversion between signals on the standard optical frequency grid. Using the device, we also demonstrated fast (<100 ps) wavelength switching of 4-channel 40-Gb/s signals. The obtained results clearly show that the proposed multiple quasi-phase-matched devices will be useful when constructing future flexible photonic networks. View full abstract»

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  • Novel approach to design high-performance large-port-count switches in low-index-contrast materials based on cascaded multimode interference couplers

    Page(s): 1548 - 1551
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    Using a novel design approach, high-performance large-port-count switches based on cascaded multimode interference (MMI) couplers are shown to be feasible in low-index-contrast materials. This approach combines the transfer matrix method, optimization of the MMI dimensions, and mode propagation analysis (MPA) for calculation of phase shifts. 1×4, 1×8, 1×16, and 1×32 switches are designed, with insertion losses of 1 dB and crosstalk as low as -31.7 dB. Also, it is shown that this approach can balance the losses for different switch states. View full abstract»

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  • Prism-based pulse shaper for octave spanning spectra

    Page(s): 1552 - 1557
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB) |  | HTML iconHTML  

    We demonstrate a prism-based pulse shaping setup that enables the shaping of ultrashort pulses with octave-spanning spectra. In contrast to gratings prisms allow for a high throughput and large bandwidths. The second-order dispersion of the prism material is precompensated by a fused silica prism sequence while higher dispersion orders are compensated by the pulse shaper. This flexible tool for dispersion compensation enables us to generate the shortest pulses ever achieved directly from an oscillator. The resulting pulse is almost transform-limited and shows a clean temporal profile with very low background. We assess the performance and limitations of the setup both experimentally and by theoretical analysis. View full abstract»

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  • Form-induced birefringence in elliptical hollow photonic crystal fiber with large mode area

    Page(s): 1558 - 1564
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    We propose a novel type of photonic crystal fiber (PCF), including an elliptical hole in its solid core. We prove the feasibility of such a fiber and investigate both experimentally and theoretically the dependence of its group birefringence on the geometric hole parameters. We show, for the first time, that form-induced birefringence can be achieved in single mode PCFs with large mode area and suggest it as a possible route for the development of polarization maintaining PCF-based LMA fiber devices. View full abstract»

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  • Neodymium-doped tantalum pentoxide waveguide lasers

    Page(s): 1565 - 1573
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    The fabrication, spectroscopic properties, and laser performance of Nd3+-doped Ta2O5 channel waveguide lasers are described. Lasing is obtained at both 1.066 and 1.375 μm with threshold pump powers as low as 2.7 mW. The rib waveguides are reactive-ion-etched into Nd:Ta2O5 layers formed by reactive magnetron sputtering. These high-index low-loss rare-earth-doped waveguides are fabricated on silicon substrates and offer the potential for integration with photonic crystal structures for compact optical circuits. View full abstract»

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  • Numerical modeling of Tm-doped double-clad fluoride fiber amplifiers

    Page(s): 1574 - 1581
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    Theoretical modeling of Watt-level average power Tm-doped fluoride glass fiber amplifiers operating at 1.87 μm is presented. To characterize and optimize these devices a computer model has been developed taking into account the full spectral information of the laser transition as well as all important ionic levels, their decay schemes and important cross-relaxation rates, being capable of modeling steady-state and especially transient characteristics of an optically pumped fiber as is needed for the amplification of short pulses. As a result, optimum fiber lengths and core sizes for maximum output power can be determined. It is shown that the influence of amplified spontaneous emission (ASE) onto amplifier efficiency and gain strongly depends on the fiber length for a given amplifier geometry, thus realistic modeling of the ASE background and its wavelength shift with respect to the fiber length is a key issue for the layout of amplifier fibers. The model is compared with experimental results obtained by amplification of 20-30-ns pulses at repetition rates in the range of 5-60 kHz. A good agreement between experiment and numerical results was reached without a substantial adjustment on the input parameters concerning amplification as well as continuous-wave ASE output power of an unseeded fiber. View full abstract»

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  • IEEE/OSA Journal of Display Technology

    Page(s): 1583
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    Freely Available from IEEE
  • IEEE order form for reprints

    Page(s): 1584
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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