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Quantum Electronics, IEEE Journal of

Issue 10 • Date October 1986

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Displaying Results 1 - 21 of 21
  • [Front cover and table of contents]

    Page(s): 0
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    Freely Available from IEEE
  • Editorial announcement

    Page(s): 1926
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    Freely Available from IEEE
  • [Back cover]

    Page(s): 0
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    Freely Available from IEEE
  • Steady-state coherent Raman beam combining with multiaxial mode lasers

    Page(s): 1942 - 1952
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    Forward-stimulated Raman scattering can be used to combine multiple broad-band pump beams into a single coherent Stokes wave. In this paper, the equations of motion for the Stokes electric field are derived in the presence of multiple pump waves propagating at slightly different angles with respect to the Stokes propagation direction. The solutions with pump depletion are presented for fully coherent pump waves. It is shown that the Raman gain is lower for incoherent pump waves than for coherent pump waves. Stokes field solutions are used to evaluate the far-field intensity of the Stokes output from a saturated Raman beam combiner. It is shown that the condition for coherent combination depends on the beam diameter, pump coherence length, and the angle between the pump and the Stokes. It is also shown that multiaxial mode Raman shifting can generate Stokes waves with higher beam quality than the pump waves, both with phase perturbed or highly distorted pump beams. View full abstract»

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  • Effect of applied electric field on the buildup and decay of photorefractive gratings

    Page(s): 1936 - 1941
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    We have measured the real and imaginary parts of the experimental rate constant of the buildup and decay of photorefractive charge gratings in cubic crystalline insulating Bi12SiO20, in the presence of an externally applied voltage. The value of the resulting field in the crystal was monitored using the crystal's own electrooptic effect. We found agreement over our entire range of fields (0-3 kV/cm) with the predictions of Kukhtarev who postulated that electrons are optically excited from a single species of trap to a single conduction band where they drift and diffuse before experiencing direct recombination to an empty trap. At the higher fields, the expected slowing of the writing and erasure processes by a factor of 20 was observed. View full abstract»

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  • Vacuum ultraviolet anti-Stokes Raman lasers

    Page(s): 1967 - 1974
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    Anti-Stokes Raman laser schemes in atomic sulphur and selenium are studied, allowing conversion of laser lines out of the 350- 178 nm range into the 200-130 nm range. The necessary population inversion with respect to the atomic metastable1S0levels is produced by photodissociation of the molecules COS and COSe with F2and ArF laser radiation, respectively. Anti-Stokes laser radiation at 167.5 and 158.7 nm for Se and at 182.0, 148.7, and 148.3 nm for S has been generated. Threshold pump energies of 0.1-20 μJ and output energies up to 5 μJ have been observed. At present, the systems are operated at low pump energies, just above threshold. It is expected that by the use of much higher pump energies and by further improvement of system parameters, output energies in the mJ range at MW peak powers will be possible for the VUV transitions. View full abstract»

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  • Theory of electric field-induced optical modulation in single and multiquantum well structures using a Monte Carlo approach

    Page(s): 2017 - 2021
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    A Monte Carlo approach is used in conjunction with the variational method to calculate quasi-bound levels in arbitrary quantum wells in the presence of transverse electric field. This approach is expected to be superior to the conventional variational approach since the results do not depend upon the choice of any starting wave solution. The technique is applied to Al0.3Ga0.7AS/GaAs quantum wells. The shift in the ground state level energies is calculated, along with the tunneling rates for the electrons and holes. We find that the tunneling rates are very sensitive to the band edge discontinuity distribution and to the barrier width in the case of multiquantum wells. The exciton binding energy is also calculated. Due to high tunneling rates at high electric fields, the photoluminescence is expected to be quenched. Consequences of these results are examined. View full abstract»

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  • Rigorous waveguiding analysis of the separated multiclad-layer stripe-geometry laser

    Page(s): 1992 - 1998
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    The waveguide modes of separated multiclad-layer (SML) laser diodes are calculated accurately by means of laterally-coupled mode equations. Thereby, it is shown that the mode losses are appreciably higher as compared to previous calculations. In particular, enhancement of the mode losses in narrow-stripe SML lasers (w leq 5 mum) may explain the relatively high threshold currents and low efficiencies reported so far for AlGaAs-GaAs and InGaAsP-InP SML lasers. A detailed investigation of various geometries reveals this laser structure to equal the related channeled substrate planar (CSP) laser with respect to the waveguide losses. View full abstract»

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  • Theory of the synchronously pumped fiber Raman laser

    Page(s): 1953 - 1966
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    Analyses of the synchronously pumped fiber Raman laser are presented under the parabolic approximation for gain shaping in both frequency and time domains. A master equation for the Stokes pulse consists of the group velocity dispersion of the fiber, the gain dispersion of the stimulated Raman scattering, a gain-shaping term due to the pump curvature, small depletion, and a walk-off effect. The pump power dependences of the Stokes power and the pulse width and the threshold condition are revealed. The frequency tunability of the present laser is also discussed. It is shown that the oscillation wavelength (carrier frequency of the Stokes pulse) will change linearly with Stokes power because of walk off during depletion. View full abstract»

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  • Frequency shift in a line center stabilized CO2laser

    Page(s): 1928 - 1930
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    A shift in frequency of 3.5 MHz from the rotational line center has been observed in a power-stabilized CO2laser operating on theP(14)line. The shift was observed during long baseline interferometry experiments and is due to gain depletion by competing rotational levels. View full abstract»

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  • Fast plasma mixing--A new excitation method for CW gas laser

    Page(s): 2022 - 2025
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    "Fast plasma mixing" is proposed as a method to generate population inversions on electronic transitions for continuous lasers. Selective excitation is accomplished by preparing collision partners for excitation in two or more separate beams. Excitation in a well-defined reaction volume and a fast flow in combination with a suitable resonator will allow the fast removal of decay products from the active volume. This pumping method will allow the operation of new CW laser systems not possible with conventional discharges and CW operation of laser systems, which at this time can only be operated as pulsed lasers. A test device has been used to study the proposed excitation method. CW operation as a fluorine laser has demonstrated the general feasibility of this method. Of special interest are molecular lasers pumped by charge or energy transfer from atomic species or by chemical reactions and excimer lasers. These lasers may offer the capability of operating CW tunable gas lasers in the visible and ultraviolet spectral regime. View full abstract»

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  • Flashlamp-pumped Cr3+:GSAG laser

    Page(s): 2058 - 2064
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    Flashlamp-pumped vibronic lasing has been demonstrated at room temperature with the garnet Cr3+: GSAG. Continuous wavelength tuning was observed from 765 to 801 nm in preliminary experiments. An energy output of 110 mJ/pulse was obtained at 784 nm with a slope efficiency of 0.12 percent. Wavelength dependent gain and loss data are presented and are discussed with reference to Cr3+: GSGG measurements. View full abstract»

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  • Internal and external field fluctuations of a laser oscillator: Part II--Electrical circuit theory

    Page(s): 2043 - 2051
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    The amplitude and phase noise spectra of the internal and external fields of a negative resistance oscillator are derived using electrical circuit theory. It is shown that the difference between internal and external fluctuations becomes important in the quantum domain (homega > kT) where external noise sources are not negligible as they often are in the classical domain (homega < kT). Using established methods to describe quantum fluctuations in electrical circuits, we obtain results in full agreement with the more exact but less general direct quantum mechanical analysis of a Fabry-Perot laser in Part I. View full abstract»

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  • A self-consistent model of the lateral behavior of a twin-stripe injection laser

    Page(s): 1975 - 1985
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    A fully self-consistent computer model of the steady-state behavior of the zero-order lateral optical field of a GaAs twin-stripe injection laser is presented which takes into account current spreading in the p-type confining layer, the effect of lateral diffusion of carriers in the active layer, and bimolecular and stimulated radiative recombination. The results predict the lateral movement of the near field of the optical signal under asymmetric drive conditions, as observed in practice. Also calculated are the corresponding carrier and current density distributions. It is shown that the near-field zero order lateral optical field can be beam steered across the facet by only 2μm, typically. However, the initial position of the beam can be controlled by the two-stripe currents and also the geometry of the device. For the case whereI_{s1} approx I_{s2}the beam movement is seen to be proportional to eitherI_{s1}orI_{s2}. The results show that beam steering is not accompanied by a negative slope to theI-Lcharacteristics. The effect of geometry and diffusion coefficient on the value of maximum current allowed before modal instability occurs is also given. View full abstract»

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  • ScBO3:Cr--A room temperature near-infrared tunable laser

    Page(s): 1931 - 1933
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    We report the first room temperature tunable laser in a borate single crystal. A tuning range of 787-892 nm has been demonstrated in a ScBO3: Cr laser. The laser loss is estimated to be 1.3 percent/cm from our preliminary laser results. Spectroscopic measurements indicate that the material is clear of absorption loss in the lasing spectral region, and the relative fluorescence efficiency for the entire Cr absorption band in the visible region is nearly unity. ScBO3:Cr holds promise as a high efficiency near-infrared tunable laser. View full abstract»

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  • Electron and hole impact ionization rates in InP/Ga0.47In0.53As superlattice

    Page(s): 1986 - 1991
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    The electron and hole impact ionization rates, α andβ, in an InP/Ga0.47In0.53As superlattice have been experimentally determined from photomultiplication data made on an InP/GaInAs superlattice photodiode. A Monte Carlo simulation of α and β in the superlattice has been developed, and the enhancement of impact ionization due to the effect of the band edge discontinuity has been investigated. The experimental ionization rates have been analyzed by the simulation. The larger β than α in the superlattice has been shown to be explained by the valence band discontinuity about two times larger than the conduction band edge discontinuity in this superlattice structure. View full abstract»

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  • Characteristics of two cathode systems for CW transversely excited CO2lasers

    Page(s): 2026 - 2031
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    The operational characteristics of CW transversely excited CO2lasers were investigated for two cathode systems: newly developed bar cathode and conventional multipin cathode. CO2lasers employing both cathode systems had similar output characteristics and gave about 10 kW output and about 19 percent efficiency. Oscillation mode patterns and discharge stabilities differed a little from each other, that is, the former had less uniform mode and less stability than the latter. However, the studies showed that we should be able to make discharge stable, and to get a uniform gain distribution and a uniform oscillation mode with a cathode system consisting of variously shaped bars. View full abstract»

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  • Definition of anisotropic aberrations in planar lenses

    Page(s): 1934 - 1935
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    Using recently developed techniques for calculating the effective index of refraction for off-axis propagation in Ti : LiNbO3waveguides and extraordinary ray tracing in uniaxial crystals we demonstrate numerically and define anisotropic aberrations and focal lengths in planar geodesic lenses for on-axis and off-axis wave propagation. View full abstract»

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  • Theory of the doped quantum well superlattice APD: A new solid-state photomultiplier

    Page(s): 1999 - 2016
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    A new superlattice avalanche photodiode structure consisting of repeated unit cells formed from a p-i-n Al0.45Ga0.55As region immediately followed by near intrinsic GaAs and Al0.45Ga0.55As layers is examined using an ensemble Monte Carlo calculation. The effects of various device parameters, such as the high-field layer width, GaAs well width, low-field AlGaAs layer width, and applied electric field on the electron and hole ionization coefficients is analyzed. In addition, the fraction of electrons which ionize in a spatially deterministic way, at the same place in each stage of the device, is determined. As is well known, completely noiseless amplification can be achieved if each electron ionizes in each stage of the device at precisely the same location while no holes ionize anywhere within the device. A comparison is made between the doped quantum well device and other existing superlattice APD's such as the quantum well and staircase APD's. It is seen that the doped quantum well device most nearly approximates photomultiplier-like behavior when applied to the GaAs/AlGaAs material system amongst the three devices. In addition, it is determined that none of the devices, when made from GaAs and AlGaAs, fully mimic ideal photomultiplier-like performance. As the fraction of electron ionizations per stage of the device is increased, through variations in the device geometry and applied electric field, the hole ionization rate invariably increases. It is expected that ideal performance can be more closely achieved in a material system in which the conduction band edge discontinuity is a greater fraction of the band gap energy in the narrow-band gap semiconductor. View full abstract»

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  • A proposed 1 kW average power moving slab Nd:Glass laser

    Page(s): 2052 - 2057
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    The design considerations of a high average power Nd : glass slab laser in which the slab moves between the pumping lamps to distribute the thermal loading over the area of the glass while maintaining high gain in the pumped volume are presented. Continuous wave operation and high repetition rate pulsed operation are projected at the 1kW average power level. View full abstract»

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  • Internal and external field fluctuations of a laser oscillator: Part I--Quantum mechanical Langevin treatment

    Page(s): 2032 - 2042
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    The amplitude and phase noise spectra of the internal and external fields of a laser oscillator are calculated using the quantum mechanical Langevin equations. The outgoing field spectra are demonstrated to be different from the internal field spectra. The outgoing photon fluxhat{N}from a laser oscillator operating at far above the threshold has a spectral density equal to the classical shot noise level,2langlehat{N}rangle. On the other hand, the internal photon number spectrum is Lorentzian, and the variance is equal to the average photon number,langlehat{N}rangle. The difference stems from the quantum mechanical interference between the transmitted internal field and the reflected zero-point fluctuation at the output coupling mirror. The relation between the present analysis and the previous noise theory of a laser is also discussed. 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