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Quantum Electronics, IEEE Journal of

Issue 5 • Date May 2009

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Displaying Results 1 - 24 of 24
  • [Front cover]

    Publication Year: 2009 , Page(s): C1
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  • IEEE Journal of Quantum Electronics publication information

    Publication Year: 2009 , Page(s): C2
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  • Table of contents

    Publication Year: 2009 , Page(s): 429 - 430
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  • Emission Directionality of Semiconductor Ring Lasers: A Traveling-Wave Description

    Publication Year: 2009 , Page(s): 431 - 438
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB) |  | HTML iconHTML  

    We use a traveling-wave model for explaining the experimentally observed changes in the directionality of the emission of semiconductor ring lasers and its different behavior when current is increased or decreased. The modulation of the cavity losses imposed by the light extraction sections together with the thermal shift of the gain spectrum and spatial hole burning in the carrier density play a crucial role in the directionality of the emission and its changes with operation current. The differences as the current is increased or decreased correspond to the different role played by spatial hole burning. View full abstract»

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  • Optimization of Ultrashort Pulse Generation in Passively Mode-Locked Vertical External-Cavity Semiconductor Lasers

    Publication Year: 2009 , Page(s): 439 - 445
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    We present a genetic algorithm based method to optimize the gain medium design of a passively mode-locked vertical external-cavity surface-emitting laser (VECSEL) for ultrashort pulse generation. Beginning with a given standard VECSEL design, we show that a simple modification to the DBR within the active mirror can significantly reduce both the duration and the chirp of the generated pulse. We demonstrate, using realistic numerical simulations, that the full-width at half-maximum of the pulse can be reduced by more than a factor of two. The required design changes come at the cost of increased sensitivity to perturbations in the active chip growth. Methods of counteracting this trend are presented. View full abstract»

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  • Numerical Modeling of Pulsed Raman Fiber Converters at 2 \mu{\hbox {m}}

    Publication Year: 2009 , Page(s): 446 - 453
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (855 KB) |  | HTML iconHTML  

    Theoretical modeling of stimulated Raman scattering (SRS) in fibers is presented for the near-infrared band around 2 mum, where pump and Stokes wave have different absorption. This model takes into account amplified spontaneous emission (ASE), SRS towards Stokes and anti-Stokes waves, absorption of the Raman medium and Rayleigh backscattering in fibers. Depending on the fiber configuration, this model includes the cavity parameters of either external or internal mirrors at the fiber ends. Input parameters are, among others, temporal profiles of the pump radiation, absorption, and gain curve of the Raman medium. The model agrees well with experimental results obtained with a GeO2 doped core fiber pumped by a pulsed and tunable Tm:silica fiber laser emitting around 2 mum. View full abstract»

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  • Reliable Low-Cost Fabrication of Low-Loss \hbox {Al}_{2}\hbox {O} _{3}{:}\hbox {Er}^{3+} Waveguides With 5.4-dB Optical Gain

    Publication Year: 2009 , Page(s): 454 - 461
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (418 KB) |  | HTML iconHTML  

    A reliable and reproducible deposition process for the fabrication of Al2O3 waveguides with losses as low as 0.1 dB/cm has been developed. The thin films are grown at ~ 5 nm/min deposition rate and exhibit excellent thickness uniformity within 1% over 50times50 mm2 area and no detectable OH- incorporation. For applications of the Al2O3 films in compact, integrated optical devices, a high-quality channel waveguide fabrication process is utilized. Planar and channel propagation losses as low as 0.1 and 0.2 dB/cm, respectively, are demonstrated. For the development of active integrated optical functions, the implementation of rare-earth-ion doping is investigated by cosputtering of erbium during the Al2O3 layer growth. Dopant levels between 0.2-5times1020 cm-3 are studied. At Er3+ concentrations of interest for optical amplification, a lifetime of the 4I13/2 level as long as 7 ms is measured. Gain measurements over 6.4-cm propagation length in a 700-nm-thick Al2O3:Er3+ channel waveguide result in net optical gain over a 41-nm-wide wavelength range between 1526-1567 nm with a maximum of 5.4 dB at 1533 nm. View full abstract»

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  • Numerical Study of Dynamical Regimes in a Monolithic Passively Mode-Locked Semiconductor Laser

    Publication Year: 2009 , Page(s): 462 - 468
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (313 KB) |  | HTML iconHTML  

    Bifurcation mechanisms of the development and break up of different operation regimes in a passively mode-locked monolithic semiconductor laser are studied by solving numerically partial differential equations for amplitudes of two counterpropagating waves and carrier densities in gain and absorber sections. It is shown that mode-locking regimes with different repetition rates can be multistable for a wide range of laser parameters and that the harmonic mode-locking regime with two counterpropagating pulses in the cavity can exhibit a period-doubling bifurcation leading to different amplitudes and separations of the pulses. The effect of linewidth enhancement factors in gain and absorber sections on the laser dynamics is discussed. View full abstract»

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  • Coherently Controlled Multifunctional Active Optical Filters

    Publication Year: 2009 , Page(s): 469 - 475
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (502 KB) |  | HTML iconHTML  

    In this paper, we propose multifunctional active optical filters using coherent nonlinear effects and quantum interference in quantum-well structures. Based on the application demand, in the absence of a control laser field, these filters can be either completely opaque or transparent. However, in the presence of such a control laser, the filter structure is activated, allowing transmission of a single frequency. We show that the amplitude and linewidth of these filters can be optically controlled, demonstrating various functionalities and performances including attenuation, amplification, and switching processes. We also show that, with proper design of such active filters, one can tune the wavelength of the filtered signal by varying the intensity of the control field. View full abstract»

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  • Polarization-, Wavelength-, and Filter-Free All-Optical Clock Recovery in a Passively Mode-Locked Laser Diode With Orthogonally Pumped Polarization-Diversity Configuration

    Publication Year: 2009 , Page(s): 476 - 487
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1732 KB) |  | HTML iconHTML  

    We proposed and demonstrated all-optical clock recovery system using a monolithic mode-locked laser diode (MLLD) that operated with less sensitivity to the polarization and the wavelength of the input data signals also with no bandpass filter to eliminate the input signal-components. The keys to this new technique are the MLLD integrated with a tensile-strained quantum-well saturable absorber and a new polarization-diversity setup by signal input orthogonally polarized to the lasing polarization of the MLLD. This approach was experimentally validated in the 40 Gbps clock recovery experiments. The results exhibited excellent performance of the clock recovery with low timing jitters (<0.3 ps) remaining small dependence on the wavelength and the polarization of the input data signals and input-signal suppression less than -30 dB with no use of the bandpass filter. We also succeeded in the stable clock recovery for the input of polarization-scrambled data signals. View full abstract»

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  • Performance and Spectral Tuning of Optically Overtone Pumped Molecular Lasers

    Publication Year: 2009 , Page(s): 488 - 498
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (295 KB) |  | HTML iconHTML  

    A laser model was developed to predict the performance of optically pumped higher overtone molecular lasers under pulsed and continuous wave (CW) excitations. This model takes into account up to 30 rotational levels in each of the eight vibrational states considered. Collision-induced relaxation among rotational levels, vibrational levels, energy transfer to translational degrees of freedom, and interactions with buffer gas, and the temperature dependence of these processes are included. Using parameters for a second overtone pulse pumped HBr laser, a complete lasing cascade can be expected at a certain pump pulse fluence resulting in maximum achievable efficiencies approaching 80%. Optimum operational pressure and temperature conditions are determined by the gas kinetic rates and line broadening effects. Frequency tuning and spectral narrowing of the laser output is possible with the insertion of intracavity filters without sacrificing laser output power owing to efficient energy redistribution between rotational levels mediated by appropriate buffer gases. CW lasing using waveguide (WG) like geometries is possible with efficiencies approaching 92% for first overtone pumped lasers. Heat conduction through the active gas enhanced by buffer gases and subsequent heat dissipation through the cooled WG walls are expected to handle the thermal load up to kW output power levels. View full abstract»

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  • Static Gain, Optical Modulation Response, and Nonlinear Phase Noise in Saturated Quantum-Dot Semiconductor Optical Amplifiers

    Publication Year: 2009 , Page(s): 499 - 505
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (526 KB) |  | HTML iconHTML  

    A rate equation model preserving charge neutrality for quantum-dot semiconductor optical amplifiers (QD-SOAs) is established to investigate the nonlinear gain dynamics in the saturation regime. The static gain of QD-SOA is calculated assuming overall charge neutrality and compared with that without overall charge neutrality. Optical modulation response and nonlinear phase fluctuation through saturated QD-SOAs are calculated numerically based on a small-signal analysis. The gain dynamics of QD-SOAs are strongly dependent on the current injection level. The carrier reservoir in the wetting layer and continuum state is necessary for QD-SOAs to operate with high gain, high saturation power, and ultrafast gain recovery. View full abstract»

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  • Polarization Maintaining Air-Core Bandgap Fibers for Terahertz Wave Guiding

    Publication Year: 2009 , Page(s): 506 - 513
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1765 KB) |  | HTML iconHTML  

    A polarization-maintaining air-core bandgap polymer fiber is proposed for low-loss terahertz (THz) wave guiding. The polarized guided modes are confined in an asymmetric core by a bandgap of periodic arrangement of square holes with round corners in the cladding. The guiding properties, including transmission bandwidth, numerical aperture, phase-index birefringence, modal absorption loss, and bend loss, are systematically investigated. The influence of background polymers on guiding properties is demonstrated in detail. Numerical simulations reveal that, while maintaining a relatively high phase-index birefringence (of the order of 10-3 ), the THz fiber shows a significant suppression of absorption loss of the background polymers (by a factor of more than 25) due to the bandgap effect that repels the modal power from the absorbent polymers. The proposed THz fiber has potential for guiding intense THz waves for polarization-sensitive applications. View full abstract»

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  • Study on Frequency Coherence Properties of Light Beams

    Publication Year: 2009 , Page(s): 514 - 522
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1585 KB) |  | HTML iconHTML  

    This paper presents a new concept of frequency coherence in the frequency-time domain to describe the field correlations between two lightwaves with different frequencies. The coherence properties of the modulated beams from lightwave sources with different spectral widths and the modes of Fabry-Perot (FP) laser are investigated. It is shown that the lightwave and its corresponding sidebands produced by the optical intensity modulation are perfectly coherent. The measured linewidth of the beat signal is narrow and almost identical no matter how wide the spectral width of the beam is. The frequency spacing of the adjacent FP modes is beyond the operation frequency range of the measurement instruments. In our experiment, optical heterodyne technique is used to investigate the frequency coherence of the modes of FP laser by means of the frequency shift induced by the optical intensity modulation. Experiments show that the FP modes are partially coherent and the mode spacing is relatively fixed even when the wavelength changes with ambient temperature, bias current and other factors. Therefore, it is possible to generate stable and narrow-linewidth signals at frequencies corresponding to several mode intervals of the laser. View full abstract»

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  • Effects of Two-Photon Absorption on Pump-Induced Refractive-Index Change in AlAsSb–InGaAs–AlAs Optical Waveguides

    Publication Year: 2009 , Page(s): 523 - 530
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (902 KB) |  | HTML iconHTML  

    Injection of transverse-magnetic polarized 1.55- mum pump light pulses having an excessively high intensity into heavily-doped AlAsSb-InGaAs-AlAs coupled-double-quantum-well optical waveguides causes a large amount of electrons in the ground state of the subbands in the conduction band to transit to the excited state and results in bandgap shrinkage as well as a large amount of vacant sites in the ground state. Consequently, the simultaneously injected continuous-wave transverse-electric polarized 1.54- mum probe light is absorbed by the valence-band electrons through two-photon absorption (TPA) and transit to the vacant sites in the ground state of the subbands in the conduction band. As a result, the probe power is reduced instantaneously but recovers at a time constant in the order of 10-10s. A theoretical evaluation of the effect of the above intersubband-pump-assisted TPA of the probe light shows that the pump-induced net refractive-index change in these devices is reduced by 50% when intersubband absorption and ISB-pump-assisted TPA of the probe light are of equal strength. Characterization of the TPA in these devices indicates that these devices have a TPA coefficient of 25 cm/GW. View full abstract»

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  • Single-Shot, High-Speed, Thermal-Interface Characterization of Semiconductor Laser Arrays

    Publication Year: 2009 , Page(s): 531 - 541
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (798 KB) |  | HTML iconHTML  

    Through a detailed characterization of thermally induced output power degradation it is possible to use junction heating as a tool to resolve thermal interfaces on mus timescales using a single-shot characterization technique. In this work, the deleterious effect junction heating has on the optical output power of a laser array is characterized and then used to infer the time-dependent junction temperature in response to current pulses of varying widths. The extracted parameters are also used numerically to model the laser as a temperature-dependent heat source for thermal simulations. This treatment allows realistic packaging and emitter-placement studies to be parametrically performed by incorporating the relationship between temperature and output power/efficiency for each emitter. In this respect, once the temperature behavior of a single emitter is quantified, the operating temperature and output power performance can be accurately predicted for any realistic physical arrangement of laser array and packaging. The experimental method presented in this work is also compared to other techniques and numerical simulations using the nonlinear heat source; this demonstrates the utility of this approach and the convenience of using easily measured parameters in thermal simulations. View full abstract»

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  • The Dispersion Measurement of Quadratic Electrooptic Effect of a Linear Conjugated Polymer

    Publication Year: 2009 , Page(s): 542 - 546
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    An experimental method based on the attenuated-total-reflection technique is reported to determine the dispersions of all quadratic electrooptic tensor elements and dc-Kerr coefficient of a linear conjugated polymer in the off-resonant region. View full abstract»

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  • Full Strain Tensor Treatment of Fiber Bragg Grating Sensors

    Publication Year: 2009 , Page(s): 547 - 553
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    Embedded fiber Bragg gratings can be subjected to arbitrary states of strain including shear strain. Such perturbations can cause coupling between polarization modes. Coupled-mode theory in Bragg gratings so far neglected this effect and only considered forward-backward coupling. Polarization mode coupling within a Bragg grating leads to interdependencies between Bragg reflection peaks which have so far been unaddressed. We formulate a full strain tensor treatment of fiber Bragg gratings, considering the coupling of the polarization modes within the grating. We give an approximation for the coupling coefficients affecting the polarization mode coupling and numerically solve the coupled-mode equations for representative states of strain. We show in which way shear strain affects the optical response of a grating and demonstrate how the fiber's beat length influences this characteristic. View full abstract»

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  • DFB Quantum Cascade Laser Arrays

    Publication Year: 2009 , Page(s): 554 - 565
    Cited by:  Papers (15)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1745 KB) |  | HTML iconHTML  

    DFB quantum cascade laser (DFB-QCL) arrays operating between 8.7 and 9.4 mum are investigated for their performance characteristics-single-mode selection of the DFB grating, and variability in threshold, slope efficiency, and output power of different lasers in the array. Single-mode selection refers to the ability to choose a desired mode/frequency of laser emission with a DFB grating. We apply a theoretical framework developed for general DFB gratings to analyze DFB-QCL arrays. We calculate how the performance characteristics of DFB-QCLs are affected by the coupling strength kappaL of the grating, and the relative position of the mirror facets at the ends of the laser cavity with respect to the grating. We discuss how single-mode selection can be improved by design. Several DFB-QCL arrays are fabricated and their performance examined. We achieve desired improvements in single-mode selection, and we observe the predicted variability in the threshold, slope efficiency, and output power of the DFB-QCLs. As a demonstration of potential applications, the DFB-QCL arrays are used to perform infrared absorption spectroscopy with fluids. View full abstract»

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  • A Theoretical Comparison of the Breakdown Behavior of \hbox {In}_{0.52}\hbox {Al}_{0.48}\hbox {As} and InP Near-Infrared Single-Photon Avalanche Photodiodes

    Publication Year: 2009 , Page(s): 566 - 571
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (195 KB) |  | HTML iconHTML  

    We study the breakdown characteristics and timing statistics of InP and In0.52Al0.48As single-photon avalanche photodiodes (SPADs) with avalanche widths ranging from 0.2 to 1.0 mum at room temperature using a random ionization path-length model. Our results show that, for a given avalanche width, the breakdown probability of In0.52Al0.48As SPADs increases faster with over bias than InP SPADs. When we compared their timing statistics, we observed that, for a given breakdown probability, InP requires a shorter time to reach breakdown and exhibits a smaller timing jitter than In0.52Al0.48As. However, due to the lower dark count probability and faster rise in breakdown probability with over bias, In0.52Al0.48As SPADs with avalanche widths les 0.5 mum are more suitable for single-photon detection at telecommunication wavelengths than InP SPADs. Moreover, we predict that, in InP SPADs with avalanche widths les 0.3 mum and In0.52Al0.48As SPADs with avalanche widths les 0.2 mum, the dark count probability is higher than the photon count probability for all applied biases. View full abstract»

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  • Feature section on the Workshop on Interconnections Within High-Speed Digital Systems

    Publication Year: 2009 , Page(s): 572
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  • JSTQE on Biophotonics 2

    Publication Year: 2009 , Page(s): 573
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  • Special issue on microwave photonics

    Publication Year: 2009 , Page(s): 574
    Save to Project icon | Request Permissions | PDF file iconPDF (117 KB)  
    Freely Available from IEEE
  • IEEE Journal of Quantum Electronics information for authors

    Publication Year: 2009 , 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