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Applied Physics Letters

Issue 1 • Date Jul 1969

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Displaying Results 1 - 16 of 16
  • Issue Table of Contents

    Page(s): toc1
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    Freely Available from IEEE
  • THE STRUCTURES OF GOLD FILMS GROWN ON CHLORIDE, HYDROXIDE AND BICARBONATE SURFACES OF ROCKSALT CRYSTALS

    Page(s): 3 - 4
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    Air‐ and vacuum‐cleaved rocksalt crystals have been treated with H2O vapor and with a mixture of H2O vapor and CO2 gas in order to study the influence of such contaminations on the epitaxial growth of gold films on NaCl crystals. Hydroxide surfaces resulting from the treatment with pure H2O vapor yielded epitaxial gold films on both vacuum‐ and air‐cleaved specimens and these were very similar in nature to those epitaxial films normally grown on air‐contaminated NaCl substrates. Bicarbonate surfaces resulting from the further treatment with a mixture of H2O vapor and CO2 gas yielded polycrystalline gold films on both the air‐ and vacuum‐cleaved specimens. View full abstract»

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  • SIMULTANEOUS MODE‐LOCKING AND SECOND‐HARMONIC GENERATION BY THE SAME NONLINEAR CRYSTAL

    Page(s): 5 - 6
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    Simultaneous mode‐locking and quasi cw second‐harmonic generation (SHG) in high‐temperature lithium niobate or barium sodium niobate of a Nd3+:YAG laser have been accomplished by electro‐optic modulation of the nonlinear medium. This technique will be useful for obtaining ``100% conversion efficiencies,'' which would not be possible by the standard intracavity method, with nonlinear crystals that are either too short or have too low a nonlinear coefficient to achieve optimum coupling of the laser. View full abstract»

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  • IMPROVED RED AND INFRARED LIGHT EMITTING AlxGa1-xAs LASER DIODES USING THE CLOSE‐CONFINEMENT STRUCTURE

    Page(s): 7 - 9
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    AlxGa1-xAs injection lasers have been fabricated over the compositional range in which the alloy has a direct bandgap transition (0 ≪ x ≤ 0.34). At 300°K the threshold current density increases with x from 12 000 A/cm2L = 8600 Å) to 56 000 A/cm2L = 7340 Å) in uncoated devices with cavity lengths of about 10 mils. In the same range of x the external differential quantum efficiency gradually decreases from 40 to 16%. These are the highest efficiencies and lowest threshold current densities ever reported for room‐temperature lasers emitting in the same spectral range. The improvement is due to utilization of the new p+‐p heterojunction structure previously used by the authors in GaAs lasers to sharply reduce the internal optical loss by improving the optical confinement and reducing the absorption coefficient in the p+ material adjoining the active region. At 77°K lasing has been achieved to 6450 Å and cw operation to 6900 Å with the emission of 0.4 W per diode. View full abstract»

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  • ACOUSTIC SURFACE WAVE MIXING ON α‐QUARTZ

    Page(s): 10 - 12
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    Experimental demonstration of the sum and difference frequency generation of surface acoustic waves on α‐quartz is reported. Individually calibrated interdigital transducers were used to generate and detect the waves. The absolute level of the nonlinearly generated acoustic power was measured for various interaction lengths and found to agree with a theory based on nonlinear coupled amplitude equations. View full abstract»

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  • PHOTOLUMINESCENCE AND STIMULATED EMISSION IN Cd3P2

    Page(s): 12 - 14
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    Optically excited recombination radiation is observed in n‐type single crystals of the II–V compound Cd3P2. Line narrowing characteristic of stimulated emission is induced at high excitation intensities. View full abstract»

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  • ORIGIN OF FIELD‐DEPENDENT COLLECTION EFFICIENCY IN CONTACT‐LIMITED PHOTOCONDUCTORS

    Page(s): 14 - 16
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    It has been established that diffusion of photogenerated carriers into the electrode can be an important limitation of the collection efficiency of surface‐barrier‐limited photoconductors. View full abstract»

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  • NONLINEAR EFFECTS OF LASER PROPAGATION IN DENSE PLASMAS

    Page(s): 16 - 18
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    Two nonlinear effects of laser propagation in dense plasmas have been analytically investigated, viz., laser penetration into an overdense plasma and the self‐focusing of a laser beam. It is concluded that for laser powers currently being used, both these effects can be quite important. View full abstract»

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  • COMMENTS ON ``LOW‐FREQUENCY CURRENT FLUCTUATIONS IN A GaAs GUNN DIODE''

    Page(s): 19 - 20
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    Our measurements of the small signal conductance of a GaAs Gunn diode at low field values do not show the frequency dependence reported by K. Matsuno. View full abstract»

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  • THE ACOUSTOELECTRIC VOLTAGE GENERATED IN CADMIUM SULPHIDE BY A NARROW INPUT ACOUSTIC SIGNAL

    Page(s): 20 - 23
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    A theoretical application of the Weinreich relationship is presented which is valid for an acoustic signal of duration less than its transit time through the medium. The acoustoelectric field produced by a piezoelectrically active acoustic wave propagating through cadmium sulphide is calculated, and excellent agreement is demonstrated between experiment and theory with the crystal both amplifying and attenuating. View full abstract»

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  • NEW cw METAL‐VAPOR LASER TRANSITIONS IN Cd, Sn, AND Zn

    Page(s): 23 - 25
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    cw laser action has been observed at 3250 Å in Cd II, 6453 and 6844 Å in Sn II, and 7479 and 7588 Å in Zn II. Laser action occurred in He‐metal‐vapor discharges at pressures of several Torr He and much lower partial pressures of the metal vapor. The first four transitions have similar operating characteristics and are believed to be excited by Penning collisions between metastable He atoms and neutral metal‐vapor atoms (similar to the mechanism for exciting the 4416 Å cw transition in Cd II). The 3250 Å transition is the first cw uv laser that can be built and operated with relatively simple techniques, similar to those used in HeNe lasers. View full abstract»

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  • ELECTRO‐OPTIC CHARACTERISTICS OF CdTe AT 3.39 AND 10.6μ

    Page(s): 26 - 27
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    The physical characteristics of high resistivity CdTe which are relevant to its use for electro‐optic modulation have been investigated at 3.39 and 10.6 μ. The unclamped electro‐optic characteristic n03r41 of CdTe was found to be 12 × 10-11 m/V and the absorption coefficient is 0.006 cm-1. Our measurements indicate that CdTe will be a very important material for electro‐optic modulation in the infrared. View full abstract»

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  • HOLOGRAPHIC CONTOURING VIA MULTIFREQUENCY LASERS

    Page(s): 28 - 30
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    Holographic images covered with range contours were produced by the multifrequency emission of a pulsed ruby. The multifrequency emission arises from the use of a resonant output reflector in the laser cavity, producing contour intervals equal to the optical thickness of the resonator. Intervals of about 1 cm and greater are attainable. View full abstract»

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  • RESONANTLY SUSTAINED BOUNDED RADIOFREQUENCY PLASMA IN A SPHERICAL CAVITY

    Page(s): 30 - 33
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    It is shown that the low‐power linear behavior of a cavity (here a spherical one) partially filled with plasma plays a fundamental role in understanding the formation of an rf plasma inside it at higher power levels. The rf plasma is found to be sustained in one of the linear resonant states of the system. With moderate rf power (10–100 w), it is possible to sustain bounded plasmas in the cavity having densities far above the critical one. The value of the density depends, as is theoretically predicted, essentially on the frequency and only slightly on the power level of the exciting signal. View full abstract»

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  • EFFECTS OF CONTACTS ON THE EMISSION FROM INDIUM ANTIMONIDE

    Page(s): 33 - 35
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    The low‐field microwave emission from InSb subjected to parallel electric and magnetic fields is strongly dependent on the type of electrical contact attached to the sample. It is suggested that the radiation is a localized phenomenon due to high‐field regions or due to a Schottky barrier. View full abstract»

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  • ELECTRON TEMPERATURE AND DENSITY IN ARGON ION LASER DISCHARGES

    Page(s): 36 - 38
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    Kinetic theory is used to calculate the electron temperature and drift velocity in a continuous argon ion laser discharge. The calculated electron mean energies range from 1.0–7.5 eV, increasing with current density to the ⅔ power. The calculated drift velocities range from ∼1–25 × 106 cm/sec. From these parameters, the electron density is obtained at typical current densities: At 500 A/cm2 the electron density is found to substantially exceed 1015 cm-3. Some consequences of these drift velocities and densities are discussed. View full abstract»

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Applied Physics Letters, published by the American Institute of Physics, features concise, up-to-date reports on significant new findings in applied physics.

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Nghi Q. Lam
Argonne National Laboratory