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Quantum Electronics, IEEE Journal of

Issue 6 • Date June 1985

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Displaying Results 1 - 25 of 43
  • [Front cover and table of contents]

    Page(s): 0
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    Freely Available from IEEE
  • Foreword to the special issue on semiconductor lasers

    Page(s): 506
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    Freely Available from IEEE
  • Analysis of ridge-waveguide distributed feedback lasers

    Page(s): 534 - 538
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    An analysis concerning the coupling efficiency and the threshold current density is presented for a ridge-waveguide distributed feedback laser. Particular attention is paid to the grating efficiency that is different under and beyond the ridge region because of different lateral environments and generally different corrugation depths. The threshold current density and its optimization are discussed for 1.55 μm InGaAsP lasers after considering the design parameters, such as the ridge width and the layer thicknesses. Both the TE and TM modes are considered. A narrow ridge helps to reduce the device threshold if the grating under the ridge is absent or is partially washed out during the ridge-overgrowth procedure. View full abstract»

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  • Analysis of cleaved coupled-cavity (C3) diode lasers - Part II: Frequency modulation, above threshold operation, and residual amplitude modulation

    Page(s): 539 - 550
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    Cleaved coupled-cavity (C3) lasers are analyzed. Results are developed for longitudinal mode tuning and enhanced frequency modulation (FM) caused by amplitude modulation of the rear section. In addition, curves of laser segment versus modulator segment current at constant output power are calculated and residual amplitude modulation of the output power when operating in the FM mode is also determined. Both long-long and long-short C3devices are studied for strong, intermediate, and weak coupling between the segments. Because of the strong sensitivity to gap spacing, results are presented for many configurations which differ only by one-eighth wavelength in that dimension. This distance corresponds to a quarter wavelength in two passes. Analytic results are compared with previously published experimental observations. View full abstract»

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  • A theoretical and experimental investigation of Fabry-Perot semiconductor laser amplifiers

    Page(s): 614 - 618
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    A simple model for the characteristics of Fabry-Perot type semiconductor laser amplifiers is developed, the model leads to several simple analytic expressions. The theoretical results have been compared with measurements using a 1.3 μm laser as an amplifier. Our results are compared to those of other authors, and we indicate how the model can be used to optimize the amplifier performance. View full abstract»

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  • 1.3 µm high-power BH laser on p-InP substrates

    Page(s): 619 - 622
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    In our fabrication of a 1.3 μm band high-power BH laser on a p-type InP substrate, 79 mW CW laser output was obtained, and the spectrum width was 10 nm at 50 mW; it also obtained a high-power pulse output of more than 200 mW at 30 ns pulse width. It shows high-speed pulse response at 2 Gbits/s. These CW and pulse lasing characteristics are reported in this paper, and we also show the output and threshold current distribution of about 1000 samples from six wafers. This high-power laser is very useful for light sources of measuring instruments. View full abstract»

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  • A 0.2 W CW laser with buried twin-ridge substrate structure

    Page(s): 623 - 628
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    An extremely high output power has been obtained with a new structure laser named the buried twin-ridge substrate (BTRS) laser. The very thin active layer formed on a ridged substrate permitted high power output increasing the catastrophic damage level. The buried stripe formed with a blocking layer remarkably improved the current confinement lowering the threshold current. A multilayer coating technique was applied to both facets to increase the front facet output. Fundamental transverse mode is achieved at more than 100 mW in CW with an uncoated laser while the maximum output power attained is as high as 200 mW in CW operation with a multicoated laser. View full abstract»

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  • Waveguiding, spectral, and threshold properties of a stripe geometry single quantum well laser

    Page(s): 634 - 639
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    In this paper we report and analyze some interesting properties observed for gain-guided GB-SQW lasers. For narrow stripe widths (leq10 mum) and thin active layers (≤150 Å) we observe a long delay time for lasing and abnormal increase in threshold current density. To explain this behavior we developed a model of waveguiding that takes into account the effect of heat profile generated along the junction plane due to carrier injection, and good agreement with experimental results is obtained. View full abstract»

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  • Anistropy and broadening of optical gain in a GaAs/AlGaAs multiquantum-well laser

    Page(s): 640 - 645
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    Anisotropic property and spectral broadening of the optical gain in a GaAs/AlGaAs multi-quantum-well (MQW) laser were precisely measured and compared with theoretical calculation to acquire a profitable model for designing of MQW lasers. The anisotropic property was well explained with calculation of allowable orientation of the electron wave. The broadening of the gain spectrum was also well explained by taking into account effect of the intraband relaxation of the electron wave. The threshold current density in the MQW structure was theoretically estimated based on the model to be lower thanJ_{th} doteq 660A/cm2. View full abstract»

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  • A new chemical etching technique for formation of cavity facets of (GaAl)As lasers

    Page(s): 658 - 662
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    A new chemical etching technique which offers excellent cavity facets of Ga1-xAlxAs lasers is reported. This technique is based on our finding that the crystallographic anisotropy in the conventional etching process of Ga1-xAlxAs multilayers depends strongly on the AlAs mode fractionxin every layer. A suitable combination of the mole fractions in the multilayer is therefore a key factor for obtaining practically vertical walls with sufficient smoothness and flatness as laser cavity facets. In fact, the reflectivity of the etched facet obtained is 28 percent, being compatible to that in the conventional cleaved facets. As a result, a CW operation with threshold current as low as 28 mA and external quantum efficiency as high as 24 percent per facet has been attained with high reproducibility. View full abstract»

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  • Coherence collapse in single-mode semiconductor lasers due to optical feedback

    Page(s): 674 - 679
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    Line broadening up to 25 GHz in a single-mode semiconductor laser with relatively strong optical feedback is reported and theoretically analyzed. Measurements of the coherence function were performed using a Michelson interferometer and demonstrate that the coherence length decreases by a factor 1000 (to approximately 10 mm) due to optical feedback. A self-consistent theoretical description is given, which is based on the view that coherence collapse is maintained due to optical-feedback-delay effects, in which quantum fluctuations play no role of importance. A connection with recently suggested chaotic behavior is made. The theoretical results obtained are in good qualitative and reasonable quantitative agreement with measurements. View full abstract»

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  • 1.3 µm buried heterojunction laser diodes under high electrical stress: Leakage currents and aging behavior

    Page(s): 726 - 736
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    Investigations on 1.3 μm DCPBH laser diodes under high electrical stress are reported. Leakage currents are identified by electro-and photoluminescence. Experiments on laser diodes with additional collector contacts to the n-InP floating layer show that blocking layer leakage is strongly enhanced by transistor action. The observed aging behavior is described. Excellent stability is observed for our diodes, more so after stress testing. It is found that stress test aging of diodes from moderate quality wafers, which typically still strongly levels off in time, is not caused by an increase in leakage current via the blocking layers, but by an increased leakage in and/or around the mesa. Though transistor action has a strong influence on device performance at high currents, thyristor breakover is shown to be absent in DCPBH-diodes: primarily due to lateral conduction in the blocking layers. Experimentally, thyristor breakover could be obtained by restricting the lateral conduction to about the channel width or less. View full abstract»

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  • [Back cover]

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    Freely Available from IEEE
  • Interpulse coherence of picosecond pulses from semiconductor lasers

    Page(s): 582 - 586
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    The interpulse coherence of picosecond pulses from semiconductor lasers has been studied using dynamic interferometric measurements of both first- and second-order correlation functions. The investigations were performed on solitary, injection locked, and external cavity operated buried optical guide lasers. The highest correlations were obtained using mode locking, while no average phase memory between pulses was observed for a solitary laser. Also, the performance of various stabilization schemes with respect to interpulse coherence is discussed. View full abstract»

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  • Carrier diffusion effects on quantum noise spectra in long wavelength BH lasers

    Page(s): 700 - 706
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    We report experimental and theoretical investigations on quantum noise fluctuations in the microwave frequency range on InGaAsP/InP BH lasers (1.3 and 1.5 μm wavelengths), taking into account lateral carrier diffusion. The theoretical analysis shows that carrier diffusion effects play an important role in the noise behavior (in particular, predicting a smoothed noise resonance-like peak), and that the RIN peak height at constant frequency is minimum when the stripe width is around the carrier diffusion length. These theoretical results are in good agreement with experimental observations up to 4 GHz, performed with an automated noise measurements system. View full abstract»

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  • Spontaneous emission in semiconductor laser amplifiers

    Page(s): 603 - 608
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    In a mode matched configuration, spontaneous emission in semiconductor laser amplifiers is enhanced by a factor which is larger than unity but which is significantly smaller than theK-factor calculated by Petermann. Using thin-slab model, we find that in typical situations, the factor is aboutK/2. View full abstract»

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  • Stable longitudinal-mode InGaAsP/InP internal-reflection-interference laser

    Page(s): 563 - 567
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    An InGaAsP/InP 1.3 μm, buried-crescent internal-reflection-interference (BC-IRI) laser has been developed. Interference is caused by internal reflections from the two faces of the InP notch built in the n-InGaAsP waveguide channel. In the best diode, threshold current was 25 mA, and the temperature variation of the lasing wavelength was 0.75 Å/°C. Mode hopping was not observed in the temperature range from 15 to 45°C, and stable single-mode operation at an injection level more than four times the threshold current was also confirmed. Furthermore, dynamic single-mode operation was obtained at modulation frequencies up to 1 GHz. View full abstract»

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  • Generation and control of bandwidth-limited, single-mode picosecond optical pulses by strong RF modulation of a distributed feedback InGaAsP diode laser

    Page(s): 568 - 575
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    Bandwidth-limited, single-mode ultrashort optical pulses with excellent coherency were generated for the first time from an InGaAsP DC-PBH distributed feedback (DFB) diode laser oscillating at 1.3 μm. It was achieved only by the laser diode itself through the most feasible and reliable method of strong RF modulation superimposed on the dc bias current. This method appears to be practically superior over the other techniques such as modelocking and injection locking because the simplest configuration with no requirement of any other optical elements and external cavity other than a laser diode as well as careful alignment and precise control. The measurement of second-order intensity auto- and cross-correlation demonstrated to be their traces completely free from noise spikes, with the contrast ratio of almost three. The time-bandwidth products of generated coherent picosecond pulses measured at different RF modulation frequencies and positive and negative dc bias current levels gave almost the values between 0.32 and 0.44 for Lorentzian pulse shape, and this fact proves definitely the bandwidth limited or coherent character. The pulsewidth was demonstrated to be continuously controllable over a range of approximately twice to three times depending upon the modulation frequency by changing the dc bias current from positive to negative. Also, the strong sinusoidal RF current superimposed on the negative dc bias current was found to be effective for high peak power operation for this InGaAsP DFB-DC-PBH diode laser. The theoretical analysis using the single-mode rate equations provides quantitatively the good agreement with the experimental results presented in this paper. View full abstract»

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  • Phase control by coating in 1.56 µm distributed feedback lasers

    Page(s): 527 - 533
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    The dependence of performances on facet phase in distributed feedback lasers was studied by changing SiN film thickness on the cleaved facet. The phase relative to the corrugation could be determined with the measurement of oscillating wavelength shift in a device with and without antireflection coating on the facets. Using the facet phase measured, we could adjust the film thickness so as to reduce the threshold current and to stabilize single longitudinal mode operation which oscillated at the Bragg wavelength. View full abstract»

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  • Longitudinal analysis of semiconductor lasers with low reflectivity facets

    Page(s): 693 - 699
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    An analysis is made of longitudinal effects in semiconductor lasers with low facet reflectivities. For this purpose, a self-consistent model is used based on the beam propagation method, which takes into account both the lateral and longitudinal dimension. The calculations show that longitudinal effects have a significant influence on the output fields in the laser. View full abstract»

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  • Low-threshold distributed feedback lasers fabricated on material grown completely by LP-MOCVD

    Page(s): 507 - 511
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    GaInAsP-InP distributed feedback (DFB) lasers emitting at 1.57 μm have been fabricated on material grown completely by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The CW threshold current of 60 mA and an output power of 6 mW per facet at room temperature have been obtained. The lasing wavelength λLunder CW operation showed a temperature coefficient (d_{lambdaL}/dT) of 0.9 Å/°C for this DFB laser over the range of10-90degC. A stable single longitudinal mode was maintained under high speed pulse modulation up to 500 ps, and sinusoidal modulation at 1 Ghz. View full abstract»

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  • The heteroepitaxial ridge-overgrown distributed feedback laser

    Page(s): 519 - 526
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    A new distributed feedback laser, the heteroepitaxial ridge-overgrown distributed feedback (HRO-DFB) laser, is proposed and demonstrated. The growth steps permit post-active-layer growth determination of the grating period, and the fabrication of this laser is simple with an automatic alignment of the current confinement to the ridge-overgrowths, which form the strip-loaded waveguide of the laser. The lateral overgrowth extending over the oxide films on both sides of the window stripe enhances the effect of grating feedback. Both LPE and MO-CVD have been employed successfully for the ridge overgrowth. The HRO-DFB laser was shown to operate in stable single-longitudinal mode with no observable mode partition events under 2 Gbit/s pseudorandom pulse modulation. The dynamic spectral width under 2 Gbit/s modulation was typically 0.5-2 Å. Other characteristics of these 1.5 μm HRO-DFB lasers include ∼8 mW/facet of single-longitudinal mode output power, and narrow beam divergence of 10° operating in the fundamental transverse mode in the junction plane. The CW thresholds were usually 50-100 mA. Transmission experiments with dispersive fibers (17 ps/km-nm) atsim1.55 mum at 2 Gbits/s over 82 km and at 420 Mbits/s over 203 km confirmed that the HRO-DFB laser is an excellent a single-frequency optical source for use in optical communication applications. View full abstract»

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  • Modulation induced transient chirping in single frequency lasers

    Page(s): 593 - 597
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    Wavelength excursions with magnitudes as large as 6 Å are seen to occur in single frequency lasers (both C3and DFB) during a transition from one power level to another. The wavelength shifts briefly toward shorter wavelengths and then back to the equilibrium value during turn-on and toward longer wavelengths and back during turn-off. These excursions, which are well explained by a model in which the carrier density is temporarily driven out of equilibrium by a change in injection current, last for hundreds of picoseconds or about one half of the relaxation resonance period. This time dependent behavior gives rise to a dramatic degradation of lightwave system performance with increasing bit rate. Laser structures which heavily damp the relaxation resonance peak are seen to exhibit the least chirp and to perform best in high speed transmission systems. View full abstract»

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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