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Quantum Electronics, IEEE Journal of

Issue 12 • Date Dec 1993

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Displaying Results 1 - 20 of 20
  • Phase-locked operation of a compact three-slab-sections radiofrequency discharge CO2 laser

    Publication Year: 1993 , Page(s): 2962 - 2971
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1352 KB)  

    In order to obtain a compact source with good power extraction and low divergence, a laser making use of both large-area discharges and laser-array principles was constructed. The near- and far-field patterns obtained from the laser working in unlocked and phase-locked conditions are presented and compared to distributions obtained by means of simple diffraction theories. A modal description to the field distribution is given, and the conditions for the attainment of the phase-locked emission are discussed, making use of the information obtained from the spectrum of beat frequencies View full abstract»

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  • Pulsed dye amplification and frequency doubling of single longitudinal mode semiconductor lasers

    Publication Year: 1993 , Page(s): 2923 - 2927
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    A single-longitudinal-mode CW AlGaAs semiconductor laser (786 nm) has been pulse-amplified in a Nd:YAG-pumped dye system by 80 dB, yielding 4-ns (FWHM) infrared pulses having energies of 1.2 mJ. These amplified pulses have then been frequency-doubled in a KDP crystal to yield 110 μJ of tunable ultraviolet radiation at 393 nm. The amplified diode laser linewidth at 786 nm is measured to be 118 MHz View full abstract»

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  • Dynamics of transient probe beam amplification via coherent multiwave mixing in a local nonlinear medium-nematic liquid crystal

    Publication Year: 1993 , Page(s): 2972 - 2976
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    The dynamics of the transient thermal-grating-mediated probe-beam amplification effect in a nematic liquid crystal film is studied with the use of millisecond laser pulses. These experimental observations and the accompanying transient multiwave mixing analysis show that peak probe gain can occur at various locations within the grating decay time; the higher the induced index change, the sooner will peak gain occur View full abstract»

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  • Stability regimes and high-frequency modulation of laser diodes with short external cavity

    Publication Year: 1993 , Page(s): 2886 - 2890
    Cited by:  Papers (5)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    The results of a linear analysis of stationary generation stability for short external cavity laser diodes in a wide range of coupling coefficients, with the effect of external cavity mode beating being taken into account, are presented. Besides the coherence-collapse transition, high-frequency instability due to mode interaction is revealed and investigated. The results of linear theory are confirmed by computer simulations. They may be considered as guidelines for the design of high-speed laser diodes with integrated passive cavities View full abstract»

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  • Dependence of sum frequency field intensity on group velocity mismatches

    Publication Year: 1993 , Page(s): 2928 - 2933
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    The sum frequency field generated by mixing phase matched optical pulses in a nonlinear crystal is studied. Specifically, the field intensity at full width half maximum (FWHM) considered as a function of the group velocity mismatch between incident pulses, and also as a function of the mismatch between the generated pulse and one of the incident pulses, is analyzed by numerical and asymptotic techniques. Both mismatch types are allowed to be arbitrary. The FWHM intensity of the sum frequency field refers here to a cross-correlation measurement between pulses separated by a time delay to τ, where the FWHM is formed with respect to varying τ, rather than to the time-based FWHM of a sum-frequency-generated light pulse for a fixed τ. It is shown that the FWHM is fundamentally insensitive to mismatch between generated and incident fields, thus providing a justification for ignoring this term. On the other hand, the FWHM is shown to vary asymptotically linearly (coefficient ≈1) with the mismatch between incident pulses View full abstract»

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  • Spontaneous lifetime and quantum efficiency in light emitting diodes affected by a close metal mirror

    Publication Year: 1993 , Page(s): 2940 - 2949
    Cited by:  Papers (7)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    The spontaneous lifetime and quantum efficiencies of dipoles placed close to a metal mirror are calculated. The importance of these effects is demonstrated in the recent experimental work on InGaAs-GaAs quantum-well light-emitting diodes (QW LEDs) in which the modulations rates were varied from 0.8 GHz to 1.4 GHz through the placement of a QW next to a Ag mirror (D.G. Deppe et al., 1990). Classical energy transfer theory is used to treat the spontaneous radiation of a QW in a semiconductor system. The spontaneous radiative lifetime and internal quantum efficiency are strongly affected by the location of the QW, which confines the dipoles, by the orientation of the dipole in the well, by the metal reflector material, and by the metal mirror thickness. In general, the internal quantum efficiency decreases when the dipole is closer to the metal, because of the nonradiative energy transfer from the dipole to the absorptive metal. The overall effect of closely spaced metal mirrors on the measurable external quantum efficiency, which is important for fast light emitting diode design, is presented View full abstract»

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  • Design and characterization of In0.2Ga0.8As MQW vertical-cavity surface-emitting lasers

    Publication Year: 1993 , Page(s): 2977 - 2987
    Cited by:  Papers (9)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB)  

    The device design, material characterization, and performance of optimized vertical-cavity surface-emitting lasers (VCSELs) are presented. The basic design goal was to increase the output power of the lasers without greatly increasing the low threshold current reported in earlier devices. The material characterization was performed by measuring in-plane lasers and broad-area VCSELs made from the same material as the small VCSELs. For 10-μm-square devices, outputs over 3 mW, device operation over 100°C, 6% wall-plug efficiency, threshold voltages under 3 V, and threshold currents under mA are reported View full abstract»

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  • Anisotropic two-photon transitions in GaAs/AlGaAs multiple quantum well waveguides

    Publication Year: 1993 , Page(s): 2934 - 2939
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB)  

    The two-photon absorption coefficient and induced nonlinear refractive index in both TE and TM modes of GaAs/AlGaAs multiple-quantum-well (MQW) strip-loaded channel waveguides are measured in the wavelength range from 1490 nm to 1660 nm. The two-photon absorption coefficient ranges from almost zero to 12 cm/GW, and the nonlinear refractive index is always on the order of 10-13 cm 2/W in the wavelength window investigated. Strong nonlinear anisotropy is observed. The values of the two-photon absorption coefficient are obtained by calibrating the inverse transmission measurements. Those of the nonlinear refractive index are obtained by monitoring the signal spectrum broadening due to self-phase modulation. The wavelength dependences of the measured two-photon absorption coefficient and nonlinear refractive index are reasonably consistent with the theoretical predictions View full abstract»

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  • Reduction of noise figure in semiconductor laser amplifiers with Ga 1-xInxAs/GaInAsP/InP strained quantum well structures

    Publication Year: 1993 , Page(s): 2950 - 2956
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    The noise characteristics of semiconductor laser amplifiers (SLAs) in the Ga1-xInxAs/GaInAsP/InP strained quantum well (QW) system are theoretically calculated and analyzed using density-matrix theory and taking into account the effects of band mixing on both the valence subbands and the transition dipole moments. The numerical results show that a reduced noise figure can be obtained in both tensile and compressively strained QW structures due to the increase in differential gain and the decrease in transparent carrier density. From a comparison among compressively strained (x=0.70), unstrained (x=0.53), and tensile strained (x=0.40) QW SLAs at a fixed carrier density and optical confinement factor, it is found that the noise figure of the tensile strained QW reaches its lowest value of 3.4 dB at average input optical power of -20 dB View full abstract»

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  • Full-vectorial mode analysis of rib waveguides by iterative Lanczos reduction

    Publication Year: 1993 , Page(s): 2859 - 2863
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    A highly efficient computer simulation code is developed to perform full-vectorial mode analysis of rib or channel waveguides. On a workstation, the mode profile and index can be calculated in 410 s if a 192×192 grid is used. The code is based on the iterative Lanczos reduction technique. Although the matrix representation of the transverse Helmholtz operator is slightly asymmetric in the vectorial mode analysis, the Lanczos reduction procedure can still converge to the eigenmode. Results for several rib waveguides are presented. They are compared to the results of the vectorial finite-element method and semivectorial analysis View full abstract»

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  • CW 20-kW SAGE CO2 laser for industrial use

    Publication Year: 1993 , Page(s): 2898 - 2909
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (932 KB)  

    A CW CO2 laser with power output of more than 20 kW is described. The laser consists of a discharge excitation system named SAGE (Silent-discharge Assisted Glow discharge Excitation) and a ZnSe or KCl transmissive window for extracting high-quality beams with axisymmetric intensity profile from a confocal positive-branch unstable resonator. SAGE is effective in forming a uniformly distributed and stable discharge in a large-volume, high-pressure gas excitation medium. Together with appropriate high-pressure gas conditions and a properly selected zeolite to adsorb water vapor in the laser chamber, the transmissive windows enable gas-sealed operations. The structure of the 20-kW SAGE laser and its performance characteristics are described. The maximum CW power of 26.5 kW with an efficiency of 16.5% is attained with the ZnSe window, and a 20.3-kW power output is extracted through the KCl window. Long-term gas-sealed operation at a CW power level of 20 kW has been demonstrated for a period of 65 h View full abstract»

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  • Optical front end for double-balanced homodyne receivers

    Publication Year: 1993 , Page(s): 2919 - 2922
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    An optical front end for double-balanced homodyne receiver is proposed. The device combines the function of a preamplifier, a 3-dB coupler, and a narrowband filter. A theoretical model is established and numerical results are presented. High gain and narrow bandwidth are predicted for this device View full abstract»

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  • Small signal analysis of THz optical-frequency conversion in an injection-locked semiconductor laser

    Publication Year: 1993 , Page(s): 2988 - 2994
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    A theory of terahertz optical-frequency conversion using highly nondegenerate four-wave mixing (FWM) in an injection-locked semiconductor laser is presented, using small-signal analysis. The optical frequency conversion can be realized through the use of cavity-enhanced highly nondegenerate FWM in an injection-locked semiconductor laser in a range of 1-THz detuning frequency between the pump and the probe waves, when the probe frequency is tuned close to one of the resonance modes. The frequency conversion is mainly attributed to the nonlinear gain effect. The maximum bandwidth of the converted signal is increased by shortening the laser cavity length. The frequency conversion efficiency is asymmetrical with respect to both the zero detuning frequency and the resonance mode where the converted signal appears. The theoretical results agree with experiments View full abstract»

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  • Influence of interstripe gain on crosscoupled-mode operation in twin-stripe lasers

    Publication Year: 1993 , Page(s): 2855 - 2858
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    Cross-coupled-mode operation in a twin-stripe laser is analyzed with particular concern for interstripe gain. When the interstripe gain of a twin-stripe laser is high, cross-coupled-mode operation is obtained with a cavity longer than the coupling length of the twin-stripe waveguide. The far-field pattern is single peaked and deflected to the low carrier density side. These characteristics are in contrast to those of the previous model without interstripe gain View full abstract»

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  • Frequency and intensity modulation characteristics of GaAs lasers in an external cavity

    Publication Year: 1993 , Page(s): 2910 - 2918
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    Frequency and intensity modulation characteristics were measured for external cavity GaAs diode lasers as a function of modulation frequency. The data, displayed as a chirp-to-power ratio (CPR), showed at low modulation frequencies a flat response and a 0° or 180° relative phase, depending on laser structure. A model incorporating a carrier-density-dependent imaginary part of the differential gain (Henry alpha factor) is developed to explain the data. The model yields simple scaling of the CPR with injection current and photon lifetime. The agreement between the model and data including scaling is excellent. These results provide strong evidence for transverse spatial hole burning in these lasers View full abstract»

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  • Bend loss of slab and fiber modes computed with diffraction theory

    Publication Year: 1993 , Page(s): 2957 - 2961
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    Radiation losses from optical waveguides that are bent into a circle are calculated with the help of Fraunhofer's diffraction theory. The validity of the result is tested by showing that it is in agreement with the known bend loss formulas of the slab waveguide of the LP01 -mode of the round step-index fiber. The accuracy of the bend loss calculations is limited by the use of a scalar theory to approximate a vector problem and by additional mathematical approximations that are required to solve an integral View full abstract»

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  • The semiconductor laser linewidth: a Green's function approach

    Publication Year: 1993 , Page(s): 2891 - 2897
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    The linewidth problem for a semiconductor laser is studied on the basis of a nonequilibrium Green's function method. Starting from a continuous-mode description of the radiation field, the low quality factor of semiconductor laser resonators is taken into account. For the case of a single lasing mode a linewidth formula is derived and related to the Schawlow-Townes expression. The linewidth is found to exceed the corresponding Schawlow-Townes value significantly. The reason for this is that gain saturation prevents large inversion even far above threshold. This phenomenon is usually ignored and is shown to yield laser linewidths comparable with experiments View full abstract»

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  • A rigorous analysis of tunable semiconductor lasers with built-in grating-assisted vertical coupler filter

    Publication Year: 1993 , Page(s): 2878 - 2885
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    A general theoretical model is established and analyzed for a tunable semiconductor laser with a built-in co-directional grating-assisted vertical coupler filter. Possible internal reflection at the gain-coupler junction is included. A rigorous coupled-mode formulation based on the composite modes in the absence of the grating perturbation and a mode-matching method at the waveguide junctions is combined with multimode rate equation analysis. The dispersion of the semiconductor material is also included in the model. The accuracy and the scope of validity of the model are verified for both weakly and strongly coupled filter structures. Simple expressions for equivalent mirror reflectance, lasing wavelength, threshold gain and side-mode suppression ratio (SMSR) are derived and typical examples examined. The effects of the filter and the internal reflection on the longitudinal mode selectivity are discussed View full abstract»

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  • Influence of end reflectivity on the excess-noise factor in distributed feedback lasers

    Publication Year: 1993 , Page(s): 2873 - 2877
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    The influence of end reflectivity on the excess noise factor in distributed feedback lasers is analyzed. It is shown that the end reflectivity affects the excess-noise factor markedly in the weak and moderate coupling region. In particular, in this coupling region the noise level in the laser structure strongly depends on the end reflectivity phase. Moreover, in the weak and moderate coupling region, the excess-noise factor decreases with an increasing end reflectivity amplitude; in the strong coupling region the opposite behavior is observed View full abstract»

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  • Envelope function calculations of linear and nonlinear optical gains in a strained-layer quantum-well laser

    Publication Year: 1993 , Page(s): 2864 - 2872
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    The linear and nonlinear optical gain of strained-layer InGaAs-AlGaAs quantum well (QW) lasers are studied theoretically, with band mixing effects taken into account. Effects of the biaxial compressive strain of the InGaAs-AlGaAs QW on the band structure are investigated by solving for the Pikus-Bir Hamiltonian. The biaxial compressive strain separates the HH and the LH subbands by pulling down the HH subbands and pushing the LH subbands away from the valence band edge. Since the C-HH transition is dominated by the TE polarization, it is expected that the TE mode gain would be substantially larger than the TM mode gain. The gain and the gain-suppression coefficient are calculated from the complex optical susceptibility obtained by the density matrix formalism. Optical output power is calculated by solving the rate equations for the stationary states with nonlinear gain suppression. The calculated L-I characteristics shows reasonable agreement with the experimental data 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..

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Meet Our Editors

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