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Quantum Electronics, IEEE Journal of

Issue 9 • Date Sep 1990

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Displaying Results 1 - 25 of 29
  • The dynamics of spatially-resolved laser eigenstates

    Page(s): 1451 - 1454
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    The existence of partially spatially-resolved laser eigenstates is proven, using the polarization walkoff provided by a uniaxial birefringent crystal. The coupling between the ordinary and extraordinary eigenstates is shown to depend greatly on the relative positions of the different elements in the cavity, leading to different eigenstates dynamics. Rotation and inhibition vectorial bistability and vectorial simultaneity are successively isolated, with the removal of the transversal degeneracy of the two eigenstates allowing a simple eigenstate selection View full abstract»

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  • A new organic electrooptic crystal: 2,6-dibromo-N-methyl-4-nitroaniline (DBNMNA)

    Page(s): 1521 - 1526
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    A new organic electrooptic crystal, 2,6-dibromo-N-methyl-4-nitroaniline, is reported. The crystal structure was determined by X-ray diffraction (orthorhombic, space group Fdd2, point group mm2, Z=16, a=11.745 Å, b=29.640 Å, c=10.807 Å). The refractive indexes were measured at several wavelengths between 500 and 1100 nm (at 632.8 nm, na=1.90, nb=1.62, and nc=1.48) and fit the data to a single oscillator Sellmeier equation. A report is presented on measurements of the linear electrooptic effect, yielding the combined coefficients na 3r13-nc3 r33, as well as the first known measurements of the quadratic electrooptic effect in an organic crystal, yielding the coefficients r42 and r51 at 514.5, 632.8, and 810 nm. Good agreement is found between the observed dispersion in the electrooptic coefficients and that predicted by the simple two-level dispersion model View full abstract»

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  • Sensitivity of grating-coupled surface emitters to length-induced phase variations

    Page(s): 1467 - 1475
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    The longitudinal mode structure of a two-gain section, three-grating surface emitting laser is studied as a function of length-induced phase variations. It is found that several mode hops occur in the course of changing the length of one of the gain sections by one grating period. Although the number of mode hops can be reduced by optimizing the design, stable, single-mode laser operation appears to require control of the optical length of each gain and grating section to better than one wavelength View full abstract»

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  • F2 pumped NO: laser oscillation at 218 nm and prospects for new laser transitions in the 160-250 nm region

    Page(s): 1529 - 1535
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    The authors recently proposed a scheme (Tech. Dig. Conf. Quantum Electron Laser Sci., April, 1989) to produce powerful coherent radiation at several wavelengths between 160 and 250 nm by optically pumping a high-lying electronic level of nitric oxide with radiation from a molecular fluorine laser. Details of this scheme and the results of a kinetic model which describes the observed absorption of F2 laser radiation by NO are presented. The successful operation of the scheme to produce laser oscillation at 218 nm is described. The possibility of using this scheme to produce laser oscillation at other wavelengths is discussed, and further extensions to produce coherent radiation at wavelengths shorter than 158 nm are proposed View full abstract»

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  • Return current in large aperture electron-beam-excited KrF lasers

    Page(s): 1546 - 1554
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    Results from a model for an e-beam excited KrF laser are presented, and the effects of return currents on plasma parameters and laser performance are discussed. The author finds that the joule heating caused by the return currents, expressed as a fraction of total power deposition, increases with increasing halogen density, increasing aperture size, increasing pressure, and decreasing power deposition. The return current electric field causes a decrease in the rate coefficients for dissociate recombination and attachment and an increase in the rate of multistep ionization. As a result, the electron density near the foil increases by more than tens of percentage points. The laser intensity in those regions also increases. These effects are practically important in lasers having apertures exceeding 1 m View full abstract»

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  • Transmission characteristics of germanium thin-film-coated metallic hollow waveguides for high-powered CO2 laser light

    Page(s): 1510 - 1515
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    Various losses such as straight waveguide losses, coupling losses from a CO2 laser, and bending losses are studied. The authors studied the fact that high-powered CO2 laser light could be transmitted through germanium-coated waveguides and investigated beam profiles from straight or bent waveguides. To ascertain the application of the waveguide in wavelengths other than 10.6 μm, the authors investigated the wavelength-dependent losses of the waveguide excited by incoherent IR light. As a result, the thickness of the deposited germanium layer can be very precisely obtained View full abstract»

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  • High average power UV generation at 0.266 μm in BeSO4·4H2O

    Page(s): 1455 - 1456
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    A report on the efficient generation of highly stable 1.7-W average power UV pulses at 0.266 μm in BeSO4·4H2O is presented. BeSO4·4H2O has been found to be a superior material for high peak-power and high average-power UV generation at 0.266 μm. A Gaussian-like beam having an average power of 1.7 W was generated without damage to the crystal at room temperature View full abstract»

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  • Recombination lasers in a flowing negative glow discharge

    Page(s): 1624 - 1632
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    A fast gas flow through a negative glow plasma creates an afterglow region where supercooled electrons are separated from energetic beam electronsto produce a population inversion by collisional recombination. A report on spatially resolved electron temperature measurements of the afterglow plasma showing electron temperatures in the range of 750-1100 K under steady-state conditions is presented. A 4-cm-long flowing hollow cathode discharge was used to obtain CW (continuous wave) recombination laser oscillation in ArI. Collisional recombination of singly and doubly ionized metal vapor species in the same type of plasma also produced pulsed laser action in infrared lines of PbI, ZnI, PbII, and SnII. The addition of H2 is demonstrated to significantly increase the laser output intensity View full abstract»

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  • Enhanced efficiency of UV second harmonic and sum frequency generation from copper vapor lasers

    Page(s): 1555 - 1558
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    The authors have generated over 460-mW output power at 255.1 and 271.2 nm with a wall-plug efficiency of 0.016% and 300 mW at 289.1 nm with a wall-plug efficiency of 0.0008%. Using an off-axis unstable resonator matched to the plasma-tube geometry and gain characteristics along with focusing lenses with reduced achromatic and spherical aberration has allowed the highest efficiencies for nonlinear UV generation from a CVL (copper vapor laser) reported to date. Current UV output powers are limited by crystal damage which may be reduced by modifying the delivery optics View full abstract»

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  • A 650 J e-beam-pumped atomic xenon laser

    Page(s): 1668 - 1675
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    The atomic xenon laser has been scaled from the 80-J per pulse output-energy level reported by N.G. Basov et al. (1986) to 650 J using a large two-sided e-beam-pumped device. The extraction volume dimensions were 0.5 m×0.65×3 m. The gas was pumped at a temporally and spatially averaged rate of 70 kW/cm3, and the spatially averaged specific input energy was 115 J/L. Output-energy measurements were made with a full-aperture calorimeter, and the temporal pulse shape of the 1.73-μm laser radiation was recorded with a spectrally filtered germanium photodiode. The device was operated with argon-xenon gas mixtures at pressures ranging from 20 to 40 psia at a temperature of 23°C, and the xenon mole fraction was empirically optimized. The maximum output energy of 650 J was obtained at an intrinsic efficiency (output energy divided by energy deposited to gas) of 0.57%. A higher efficiency of 0.85% was achieved by using a shorter e-beam pulse, at a reduced laser output energy of 495 J. A possible explanation for the observed laser pulse shape is given View full abstract»

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  • VUV stimulated anti-Stokes Raman emission in inverted atomic selenium

    Page(s): 1536 - 1545
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    Stimulated anti-Stokes Raman scattering at 145.7 nm in inverted Se is generated by photolysis of OCSe at 193 nm and the subsequent up-conversion of 205.1-nm pump radiation. The tuning profile is characterized with OCSe pressure, the energies and relative timing of the pump and photodissociation lasers, and CO and Ar buffer-gas pressure. The use of CO as a buffer gas is discovered to be detrimental to the anti-Stokes output. Sixteen competing stimulated emission channels are found to suppress anti-Stokes emission on exact 4p 4 1S0-4p3 5s3 P01 pump resonance View full abstract»

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  • The perylene derivative BASF-241 solution as a new tunable dye laser in the visible

    Page(s): 1516 - 1520
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    Basic optical properties of the perylene derivative BASF-241 solution in chloroform relevant to its application as a dye laser were measured. The fluorescence spectrum, excited by frequency-doubled (532-nm) Nd:YAG laser pulses, shows three pronounced peaks centered at 540, 580, and 630 nm, with a Stokes shift and mirror image in relation to the absorption spectrum. The quantum yield was about a unity, with a lifetime of 5.0±0.5 ns. Addition of trichloroacetic acid (CCl3COOH) causes a red shift of absorption and fluorescence spectra by about 750 cm-1-L/mol. In a cavity consisting of a ~100% reflecting back mirror and an 8% reflecting output coupler, lasing was obtained at 577 nm, with a threshold of ~10 μJ/pulse. Using a grating, a tuning range of almost 20 nm was obtained, centered at the 0-1 fluorescence emission peaks View full abstract»

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  • Single-frequency operation in solid-state laser materials with short absorption depths

    Page(s): 1457 - 1459
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    Single-frequency output power of 35 mW has been observed in 3.0% doped Nd:YVO4 pumped with a 200-mW laser diode. The single-frequency operation is due to the spatial overlap of longitudinal modes at the surface of a mirror in the laser cavity where the material is pumped. The strong absorption coefficient at 808.7 nm and narrow bandwidth of the Nd:YVO4 only allow a single laser mode to operate. The effect is modeled theoretically and compared with the experiment View full abstract»

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  • Enhanced performance of the iodine monofluoride (491 nm) laser

    Page(s): 1620 - 1623
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    The impact of substituting HI for CF3I as the iodine donor in the discharge-pumped iodine monofluoride (IF) laser at 491 nm has been investigated. More than an order of magnitude improvement in output pulse energy has been observed and is attributed to more efficient production of low-lying (v'<5) vibrational levels of the IF (D') ion pair state. Preliminary evidence indicates that vibrational excitation of HI (X1Σ+ ) assists in the relaxation of the D' state population. The increased net small-signal gain of D'→A' (v'=0→v") transitions in HI-containing gas mixtures has the effect of intensifying the 491-nm (0.15) bandhead relative to the lower gain transitions View full abstract»

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  • Quantum-confined field-effect light emitters: device physics and experiments

    Page(s): 1481 - 1491
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    Extended experimental results on three-terminal quantum-confined field-effect light emitters with current injection and field control of luminescent characteristics in the quantum-well structure are reported. By incorporating superlattice buffer layers (SLBLs), the quantum efficiency of the device is dramatically improved and equivalently nonradiative recombination processes are sufficiently suppressed at room temperature. The red-shift of the emission spectra by the quantum-confined Stark effect assures that the electric field is effectively applied to the quantum well. The experimental data on the transient responses of emission intensity to input voltage pulses show fairly good correspondences with theoretical prediction and previous photoluminescence experiments. The authors discuss the ultimate capability of high-speed switching and point that an optical pulse with a duration as short as 30 ps and involving more than 100 photons can be generated by scaling down the size of the device with 1% external efficiency View full abstract»

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  • Lasers with super-Gaussian mirrors

    Page(s): 1500 - 1509
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    A systematic theoretical and experimental investigation of unstable resonators with variable reflectivity mirrors of a super-Gaussian profile is presented. The validity of a geometrical optics formalism for an algebraic mode calculation is discussed in comparison to the diffraction theory. A new method for the calculation of the output energy by means of a closed-form relationship that accounts for the effects of the transverse mode profile on gain saturation is presented. Various dielectric super-Gaussian mirrors have been fabricated, characterized, and tested in a pulsed Nd:YAG laser. Super-Gaussian resonators can provide even higher output energies than those of traditional unstable resonators and with better beam-focusing properties View full abstract»

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  • Spontaneous emission rate alteration in optical waveguide structures

    Page(s): 1492 - 1499
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    Optical microcavities hold technological promise for constructing efficient, high-speed, semiconductor lasers. Achieving the desired effects depends on the degree to which spontaneous emission may be altered by the presence of the cavity. The radiating modes of an oscillating electric dipole placed between two planar metallic mirrors (one-dimensional confinement) and placed in an optical-wire structure (two-dimensional confinement) are discussed. The analysis is carried out using a mode-counting method. The authors show that this method is simpler and more intuitive than traditional classical and quantum electrodynamical calculations. Using the results of the analysis, it is found that an optical wire provides much larger spontaneous-emission-rate alteration than a planar mirror structure View full abstract»

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  • Effect of cladding layer thickness on the performance of GaAs-AlGaAs graded index separate confinement heterostructure single quantum-well lasers

    Page(s): 1476 - 1480
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    The thinning of cladding layers of GaAs-AlGaAs graded index separate confinement heterostructure single quantum-well (GRINSCH-SQW) lasers offers several advantages. These advantages include easier fabrication of surface grating-based lasers and ridge lasers, the reduction of growth time and source-material use, and the more effective removal of heat due to lower thermal resistance. Experimental results from GRINSCH-SQW lasers showing that typical cladding thicknesses of 1.5 to 2 μm are much thicker than necessary are presented. Lasers with cladding layers as thin as 4500 Å have not shown any increase in threshold current. Theoretical analysis shows good agreement with the experimental results on the minimum cladding thickness necessary to prevent an increase in the threshold current. The differential quantum efficiency is theoretically considered and is found to be more sensitive to cladding-layer thickness View full abstract»

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  • Spectral and bandwidth characteristics of a high-pressure Xe laser in a several kilogauss field

    Page(s): 1653 - 1660
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    A technique based on the Zeeman effect has been developed for determining the gain bandwidth of the 1.73-μm laser line of the high-pressure atomic xenon laser. A bandwidth in the range of 0.14 to 0.37 cm-1 has been determined by this method. Lasing bandwidths for the 1.73-, 2.03, 2.63, and 2.65-μm lines have also been determined for pump rates in the range 0.3 to 1.8 kW/cm3. The effect of the magnetic field on the spectral characteristics of these lines is also given View full abstract»

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  • Extremely narrow spectral linewidth and low chirping of the MQW-DFB-PPIBH laser diode

    Page(s): 1460 - 1466
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    The low threshold current of 9 mA, the high side-mode suppression ratio of more than 45 dB, the extremely narrow spectral linewidth of 1.1 MHz, and the low chirping of 2.8 Å at -20 dB at 2 Gb/s nonreturn to zero (NRZ) modulation have been achieved in the multiple quantum well (MQW) distributed feedback (DFB) p-substrate partially inverted buried heterostructure (PPIBH) laser diode. The spectral linewidth of 1.1 MHz is the narrowest value among 300-μm-length solitary laser diodes. These results suggest that the MQW-DFB laser diodes are a promising light source for longer distance and higher bit-rate optical communication systems and coherent optical communication systems View full abstract»

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  • High efficiency, high-energy performance of an X-ray preionized Ar-Xe laser

    Page(s): 1647 - 1652
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    Improved performance has been obtained from the X-ray preionized argon-xenon laser by using a spiker-sustainer circuit to efficiently pump the discharge. An output of 420 mJ was obtained from a 0.4-L active volume at 2-atm pressure with an overall efficiency of 1%. An efficiency of 4.1% due to the sustainer contribution alone was also realized View full abstract»

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  • A study of an electron-beam excited atomic xenon laser at high energy loading

    Page(s): 1661 - 1667
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    Operation of an electron-beam excited atomic xenon laser was investigated at pump rates between 40 W/cm3 and 1 kW/cm3 with pump times of 1 ms. Effects of cavity loss, gas mixture, and pump rate on laser performance were studied under selected conditions. The variation in laser power in 99.5% argon and 0.5% xenon selectively lasing at 1.73 or 2.6 μm was investigated as a function of pump power. It was found that the laser pulsewidth was shorter than the pump pulse and increased as the pump rate decreased, consistent with a temperature-induced effect. Lasing with broadband optics was investigated as the xenon concentration was varied and as helium or neon was combined with argon-xenon mixtures. Strong lasing was observed for xenon concentrations up to 20%. Addition of helium resulted in a slight increase in laser pulsewidth and caused lasing at 2.03 μm to increase at the expense of lasing at 1.73 and 2.6 μm View full abstract»

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  • Scaling characteristics of the XeF (CA) excimer laser

    Page(s): 1559 - 1568
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    The scaling characteristics and medium properties of an injection-controlled XeF(CA) laser pumped by a 10-ns-high current density electron beam have been investigated. A five-component laser gas mixture, consisting of F2, NF3 , Xe, Kr, and Ar was optimized for the scaled laser conditions, resulting in 0.8-J output pulses at 486.8 nm, corresponding to an energy density of small-signal-gain measurements combined with kinetic modeling permitted the characteristics of the dependence of net gain on the electron-beam energy deposition and gas mixture composition, resulting in an improved understanding of XeF(CA) laser operation View full abstract»

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  • Quenching of 6p[3/2]1 and 6p[5/2]2 levels of atomic xenon by rare gases

    Page(s): 1633 - 1638
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    The rates of quenching the 6p[3/2]1 and 6p [5/2]2 levels of atomic xenon by rare gases have been measured. The quenching rates are obtained from the 6p fluorescence decay following two-photon excitation. Radiative lifetimes of the two 6p levels are also measured. Rates from quenching Xe 6p[5/2]2 by neon, argon, and krypton are larger by a factor of 5 to 40 than the same rates for Xe 6p[3/2]2. Quenching of 6p[5/2]2 by helium is found to be a factor of 12 smaller than it is for 6p [3/2]1. The implications of these rates for high-pressure atomic xenon laser kinetics are discussed View full abstract»

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  • Time-resolved measurements of excited state densities in a copper vapor laser

    Page(s): 1609 - 1619
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    Time-resolved measurements of copper and neon buffer gas excited-state densities in a copper vapor laser (CVL) during the excitation pulse and early afterglow are reported for both optimum and nonoptimum power-input conditions. The optimum condition results demonstrate that the termination of the laser pulse in the CVL is due not only to filling of the lower laser level, but also to a reduction in the upper laser-level pumping related to the collapse of power input to the plasma during the excitation pulse. Time-resolved measurements of excited-state densities over a wide range of input-power conditions clearly illustrate that the increase in copper density with power input reduces the peak electron temperature in the plasma during the excitation pulse. This reduction in peak electron temperature is important in limiting the scaling of CVL output power with input-power-copper density 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