bluuebunny/crossref_metadata_2025 huggingface dataset:
Segmented surface-wave amplifier exhibiting net terminal gain at 86 MHz
Authors: Cambon G. , Roustan C. , Rouzeyre M.
Published: January 2004

In our work on the amplification of Bleustein-Gulyaev waves in photoconducting CdS crystals, we have found that the gain as a function of electric field is quite symmetric about the synchronous value. We have therefore been able to achieve amplification with a segmented structure consisting of an interdigital electrode. The unequal spacing between fingers produces amplification in the region where the field is positive, which is in excess of the attenuation in the region where the field is negative. The spacings between adjacent electrodes are 500 and 250 μm, giving a periodicity of 850 μm; the length of the active region is 6 mm. The experimental electronic gains obtained were 19 dB at 43 MHz and 32 dB at 86 MHz with an applied voltage of 130 V; 4 dB net gain was obtained at 86 MHz. It has been observed that the electronic gain is sensitive to the photoexciting light wavelength. We give an interpretation of this phenomenon based on the relative penetration depth of the mechanical wave, of the photoexcited carriers, and of drifting electric field.
Nonlinear interaction of Bleustein-Gulyaev waves in photoconducting CdS
Authors: Sagnes G. , Roustan C. , Rouzeyre M.
Published: January 2004

We report on an experimental study of the nonlinear interaction of Bleustein-Gulyaev surface waves in photoconducting CdS. The two oppositely travelling surface waves at frequency f=43 MHz are first amplified and then interact under a semitransparent diffused electrode. The acoustic convolution product is observed at 86 MHz. The level of the detected signal is 36 dB below the two input ones with an interacting length of only 2 mm. There is clear evidence that this nonlinear interaction results from electron phonon scattering; we give the expression for the second-order potential.
Cathodoluminescence of rare-earth oxysulfide thin films
Authors: Alves R.V. , Buchanan R.A. , Maple T.G.
Published: January 2004

Rare-earth oxysulfide films with an intrinsic cathodoluminescent efficiency equivalent to that of the same material in powder form have been produced. These films withstood the maximum power density of the electron beam apparatus, 7 W/mm2, without damage or intensity saturation. An apparatus-limited luminance of 4×104 fL from a terbium-activated lanthanum oxysulfide film using 12-kV cathode-ray excitation was measured. A multilayer film of lanthanum oxysulfide activated with Eu, Tb, and Tm was produced whose emission color is voltage dependent.
Stress-pulse propagation in solids: a closer look at dispersion
Authors: Felix M.P. , Ellis A.T.
Published: January 2004

It is found that when a short-duration plane-compressive stress pulse is propagated in various solid metals, the initially compressive pulse develops a tensile tail indicative of dispersion. This dispersion occurs without the stress pulse impinging upon external boundaries or upon any classically recognized internal boundaries. This phenomenon also occurs in water in which it is demonstrated experimentally that the dispersion mechanism is the scattering of the wave by the small amount of air normally present in water. It is believed that the pulse dispersion in the metals is likewise caused by scattering of the wave by the very small but extremely numerous defect-related voids that exist in all metals, even if they are carefully prepared metallic single crystals.
Observation of coherent microwave radiation emitted by coupled Josephson junctions
Authors: Finnegan T.F. , Wahlsten S.
Published: January 2004

We report here the results of a preliminary study of coherent microwave radiation emitted by a small array of interacting Josephson tunnel junctions, including the first direct observation of the superradiant state in pairs of junctions.
The on-state in chalcogenide threshold switches
Authors: Lee S.H.
Published: January 2004

The on-state of the chalcogenide glass threshold switch is analyzed on experimental results which call for thin free-carrier space-charge regions at the electrodes. Carriers are assumed to tunnel through the corresponding barriers which are, in turn, maintained by the joint action of the electron and hole flow. The calculated voltage-current relationship is in excellent agreement with observations.
Charging of polymer foils using liquid contacts
Authors: Chudleigh P.W.
Published: January 2004

A very simple technique is reported for charging 25.4- and 50.8-μm foils of polyfluoroethylenepropylene (FEP) using conducting liquid contacts. At 23°C in laboratory atmosphere, decay time constants exceed 20 years for foils initially charged to 500 V with ethyl alcohol contacts. Measurements of accelerated decay at 100°C are interpreted in terms of rapid injection and trapping of surface charge followed by drift of thermally generated carriers under the internal field of the trapped surface charge.
High-speed photography of surface flashover of solid insulators under impulse voltages in vacuum
Authors: Cross J.D. , Srivastava K.D.
Published: January 2004

Results are presented of an investigation into the flashover of glass and high-density alumina cylinders 1.25 cm in length between uniform field electrodes in vacuum. Photographs taken with an image-converter camera with a framing rate of 2×107 frames/sec are shown. At approximately 80% of the voltage required to produce a flashover, partial discharges occur. When the voltage applied to the gap is increased to breakdown level, the partial discharges persist as the first stage of a two-stage arc formation. The development of the discharge is shown to be consistent with a flashover mechanism involving charging of the solid surface by electrons emitted at the cathode.
Observation of superconductivity in an indium-silicon bistable device
Authors: Broom Ronald F.
Published: January 2004

Superconducting behavior characteristic of a weak link is found to occur in the low-resistance state of a bistable nonvolatile switching device, formed by two closely spaced In contacts on Si.
Phase-matched submillimeter wave generation by difference-frequency mixing in ZnGeP2
Authors: Boyd G.D. , Bridges T.J. , Patel C.K.N. , Buehler E.
Published: January 2004

Using two step-tunable CO2 lasers, we have observed phase-matched generation of frequencies 70 <ν<110 cm−1 by nonlinear mixing in a birefringent ternary semiconductor, ZnGeP2. An observed power of ∼1.7 μW at 83.37 cm−1 gave a signal-to-noise ratio of ∼1000 with a Ge:Ga detector. In combination with tunable optical lasers, this technique should yield a tunable source of submillimeter wave radiation for high-resolution spectroscopy.
Vibration-vibration energy transfer in CO2 glow discharges
Authors: Gower M.C. , Carswell A.I.
Published: January 2004

Short-duration 10.6-μm pulses are used to perturb low-pressure CO2 laser discharges. Various spontaneous emissions from the glow discharge are monitored as they return to their steady-state values. Vibration-vibration (VV) pumping between CO2(ν3) and CO (produced by dissociation or premixed) as well as N2 has been observed in three independent studies. Data obtained from these studies correlate well with each other. When the reciprocal time constant for the VV process is plotted against pressure, a straight line is obtained as predicted by theory. The slope of this line is consistent with rate-constant data taken from laser-induced fluorescence experiments.
Supersonic electrical-discharge copper vapor laser
Authors: Russell G.R. , Nerheim N.M. , Pivirotto T.J.
Published: January 2004

A copper vapor laser, utilizing a pulsed discharge transverse to a supersonic flow of copper vapor, argon, and helium and oscillating at 5106 and 5782 Å, has been built and tested. Laser energy densities per pulse of 2.5 μJ cm−3 have been achieved to date. Laser pulse widths of up to 185 nsec have been obtained with delay times after initiation of the current pulse of 220–250 nsec. Both the delay time and pulse width are in good agreement with theoretical predictions. Quenching of the laser pulse is shown to be due to a rapid increase in the rate of equilibration of the lasing levels by electron collisions, and to a decrease in the differential pumping of the lasing levels from the ground state because of a decay in the electron temperature.
Yellow-light-emitting ZnSe diode
Authors: Park Y.S. , Geesner C.R. , Shin B.K.
Published: January 2004

Yellow-orange luminescence peaking at 5900 Å was obtained from the aluminum-doped ZnSe diode. The external quantum efficiency of 0.1% has been attained at 300 °K. Brightness levels of 200 fL have been measured at an input power of 100 mW.
Anisotropy in the electrical properties of n-type (221) Si/(112̄2) Al2O3
Authors: Thorsen A.C. , Hughes A.J.
Published: January 2004

Studies of the resistivity and Hall effect in n-type (221) Si/(112̄2) Al2O3 films have shown that the electron mobility is a strong function of azimuthal direction in the plane of the film. Typical variations in mobility between high- and low-mobility directions are approximately 40%. The anisotropy in mobility is explained on the basis of piezoresistance effects in Si, due to stresses induced by the differential thermal contraction between the Si and the Al2O3 substrate.
Growth of uniaxial magnetic garnet films by rf sputtering
Authors: Cuomo J.J. , Sadagopan V. , DeLuca J. , Chaudhari P. , Rosenberg R.
Published: January 2004

Epitaxial films of gadolinium-gallium-substituted yttrium iron garnet (Gd : Ga : YIG) films have been grown by rf-sputtering techniques on 〈111〉 gadolinium gallium garnet (GGG) substrates. The as-deposited films were annealed to yield crack-free epitaxial garnets, which exhibited movable magnetic (bubble) domains. Typical magnetic data for the sputtered Gd : Ga : YIG films are presented.
Optical waveguide formed by electrically induced migration of ions in glass plates
Authors: Izawa Tatsuo , Nakagome Hiroshi
Published: January 2004

Low-loss waveguides for integrated optical devices are formed by electrically induced migration of ions in glass plates. The guiding region is located beneath the substrate glass. The transmission loss of the waveguides is estimated to be less than 0.1 dB/cm.
Visual display of fatigue damage by means of exoelectron emission
Authors: Baxter William J.
Published: January 2004

A channeltron electron multiplier array has been used to detect exoelectron emission during the the fatigue cycling of aluminum. This provides the first two-dimensional visual display of the onset and development of fatigue damage. Exoelectron emission is detected in less than 0.1% of the fatigue life and increases in intensity with continued fatigue cycling; final failure occurs in the region of most intense emission.
Ion implantation into insulators: charge-removal studies using ion-induced characteristic x rays
Authors: Beezhold Wendland , EerNisse E.P.
Published: January 2004

The effectiveness of a number of charge-removal techniques during ion implantation into insulators has been examined by monitoring the ion-induced characteristic x-ray emission of target atoms during proton implantation. Successful removal of charge buildup occurs for samples which are coated with a thin conducting surface layer and for samples which have intimate contact between the implanted region and a conducting mask and are flooded with a defocused ion beam.
Interaction of ultrasonic surface waves with conduction electrons in thin metal films
Authors: Bierbaum P.
Published: January 2004

Ultrasonic surface waves propagating on a piezoelectric substrate are accompanied by electric fields which can interact with charge carriers in an adjacent medium. This interaction and the resulting attenuation of the elastic surface wave have been measured for different metal films on a quartz single-crystal substrate. As the films are deposited on the substrate, the resistivity of the films decreases continuously, and it was found that the interaction between the ultrasonic wave and the charge carriers in the film reaches a maximum for a resistivity of the films on the order of 5 MΩ/sq, but the magnitude of the resulting attenuation of the surface wave was dependent on the film material. Values of the maximum attenuation varied between 0.27 dB/cm for bismuth and 2.8 dB/cm for copper at a frequency of 31.5 MHz. A theoretical model was developed which showed good agreement with the experimental results for the materials used.
Fluorine ion implantation profiles in gallium arsenide as determined by Auger electron spectroscopy
Authors: Harris J.S. , Harris J.M. , Marcus H.L.
Published: January 2004

The distribution of fluorine ions implanted into gallium arsenide has been determined through the use of Auger electron spectroscopy combined with thin-layer removal by argon ion sputtering. This technique is a chemical measure of the ion distribution and thus is not affected by the electrical properties of the implanted species. The leading edge and depth of the peak fluorine concentration are in fair agreement with the calculated LSS distribution; however, the trailing edge exhibits a tail which extends much deeper than expected. This tail is assumed to be due to damage-enhanced diffusion.
Influence of implantation temperature and surface protection on tellurium implantation in GaAs
Authors: Harris J.S. , Eisen F.H. , Welch B. , Haskell J.D. , Pashley R.D. , Mayer J.W.
Published: January 2004

GaAs samples were implanted with tellurium at room temperature or at 150 °C and annealed to 750 °C with an SiO2 or Si3N4 protective layer. The highest electron concentrations and brightest photoluminescence were obtained for the hot implants with a Si3N4 protective layer.
Calculation of thermal diffusivity from measurements with the sine wave modulation method: modification of Cowan's equations
Authors: Penninckx R.
Published: January 2004

Cowan's equations have been replaced by an equation giving the thermal diffusivity α of a thin plate uniquely as a function of the measured quantities Δ and δ0, Δ being the phase difference between the temperature variations at the two faces of the slab and δ0 the phase difference between the modulated heating beam and the nonheated face. A very simple approximate equation is also proposed for Δ>1.
Solid-state self-focusing surface waveguide (microguide)
Authors: Nishizawa Jun-ichi , Otsuka Akira
Published: January 2004

A thin-film optical waveguide with self-focusing caused by controlled distribution in the thickness was made of nitrocellulose and suspended in air. Undulation of the guided light beam was observed in the film, as well as in the self-focusing optical fiber, when a He–Ne laser beam was injected at a place apart from the thickest center of the film. From this experiment, it has been shown that the transverse focusing effect in thin-film optical-wave transmission is obtained by the distribution in thickness of the film.
Charge storage of acoustic rf signals
Authors: Bert A.G. , Epsztein B. , Kantorowicz G.
Published: January 2004

A method is described which allows the recording of an rf signal and its restoration at any time after a few microseconds following the writing. Once the signal is converted into a surface elastic wave on a piezoelectric substrate, an electron beam impinges upon the surface during a short time. A charge-stored image of the signal is realized by the secondary electrons. Reading is achieved by means of a second current pulse which erases the surface charge distribution, exciting two elastic waves. One of them is the time-inverted image of the signal. An attenuation of 63 dB has been measured at 30 MHz on quartz after a storage time of about 1 min.
Optoacoustic properties of thallium arsenic sulphide, Tl3AsS4
Authors: Roland G.W. , Gottlieb M. , Feichtner J.D.
Published: January 2004

We report on the growth and the measurement of optical and optoacoustic properties of Tl3AsS4, a new single-crystal sulfosalt material. It is transparent from 0.6 to 12 μm, has an optoacoustic figure of merit (relative to fused silica) of over 500 (at 0.6328 μm), and rather low acoustic losses.
Admittance spectroscopy of deep impurity levels: ZnTe Schottky barriers
Authors: Losee D.L.
Published: January 2004

A new method of deep-level spectroscopy is demonstrated on ZnTe Schottky-barrier diodes. Peaks in conductance measured as a function of temperature and frequency yield level depths and capture coefficients. A small-signal theory is developed for numerical comparison to capacitance data, yielding level types and densities.
Energy transfer from Tl+ to Gd3+ in inorganic glasses
Authors: Reisfeld Renata , Morag Sh.
Published: January 2004

Energy transfer from Tl+ to Gd3+ is reported in borax and phosphate glass. It was found that the 6P7/2→8S7/2 fluorescence of gadolinium could be increased manyfold when excited through 1S0-3P1 absorption of Tl+. It is suggested that the energy from the thallium ion is transferred directly to the 6P7/2 state of gadolinium.
cw gas breakdown in argon using 10.6-μm laser radiation
Authors: Franzen Douglas L.
Published: January 2004

A very intense gas breakdown spark has been extended to a continuous arc in argon using a focused cw CO2 laser. To achieve cw breakdown, the focal volume of a mirror focusing a high-power CO2 laser was preionized by a single pulse from a CO2 TEA laser. The electron density created by the pulsed laser is sufficient to start the cw plasma. This letter reports accurate measurements of pulsed thresholds as well as preionized cw thresholds for breakdown in argon. Also, a study of the time development of the cw plasma is presented.
Measurement of surface contamination using oxygen-ion-induced x rays
Authors: Saltmarsh M.J. , van der Woude A. , Ludemann C.A.
Published: January 2004

X rays induced by 20-MeV oxygen ions have been used to search for trace quantities of lanthanum on the surface of a NaCl crystal. The results demonstrate the sensitivity of the method to small quantities of heavy elements present on low-Z matrices.
Influence of carrier diffusion on the intrinsic response time of semiconductor avalanches
Authors: Hulin R. , Goedbloed J.J.
Published: January 2004

The intrinsic response time τi of semiconductor avalanches has been determined from microwave measurements on Si, Ge, and GaAs IMPATT diodes of various structures (n+-p, p+-n, Schottky barrier). A theory has been developed to calculate τi for these diodes. It was found that the effect of carrier diffusion has to be taken into account to remove a systematic discrepancy between experimental and theoretical values of τi. For Si the value of the average high-field diffusion constant D̄=80 cm2/sec for E=400 kV/cm, taken from the literature, could be used satisfactorily. For Ge and GaAs, where no information on D̄ is available, D̄=100 cm2/sec for E=200 kV/cm and D̄=250 cm2/sec for E=400 kV/cm, respectively, had to be chosen to explain the experimental values of τi.
Ion bombardment fabrication of optical waveguides using electron resist masks
Authors: Goell J.E. , Standley R.D. , Gibson W.M. , Rodgers J.W.
Published: January 2004

Fabrication of a circular strip waveguide by ion implantation of fused silica through a mask made by electron-beam exposure of polymethylmethacrylate (PMMA) is described. This technique has an advantage in its simplicity and the small number of processing steps involved. Guidance of 0.6328-μm light from a He–Ne laser through the guide is demonstrated.
Acoustic modulation of light by nematic liquid crystals
Authors: Bertolotti M. , Martellucci S. , Scudieri F. , Sette D.
Published: January 2004

An acoustic modulator using a liquid crystal and a piezoelectric driver is described. The response time of the modulator is less than the time needed for the onset of mechanical stress. Actually it is governed only by the electromechanical properties of the piezoelectric driver used.
Reduction in the rate of increase of spontaneous emission from double-heterostructure injection lasers at threshold
Authors: Paoli Thomas L.
Published: January 2004

An abrupt reduction in the rate of growth of the spontaneous emission has been observed to occur at the lasing threshold of stripe-geometry double-heterostructure injection lasers. The observations are contrary to a previously published result of Sommers and imply that increases in the quasi-Fermi level separation with current are significantly reduced at the lasing threshold in agreement with present theoretical predictions.
Wavelength dependence of optimum thickness of Cs–O low-work-function surfaces
Authors: Sonnenberg H.
Published: January 2004

The amount of Cs–O low-work-function surface material required to optimize the photoresponse of InAs0.4P0.6 depends upon the wavelength at which the response is to be maximized. It is shown that the optimum thickness increases exponentially with wavelength.
Additional unique property changes observed during TiNi transition
Authors: Wang Frederick E. , Buehler William J.
Published: January 2004

Some unique physical property changes related with the TiNi martensitic transition, such as ``memory'' effect, have been known for some time. In this letter we report some additional observations which are of interest and are related to the TiNi transition.
Degradation of a Gunn diode by dislocations induced during thermocompression bonding
Authors: Hasegawa F. , Ito H.
Published: January 2004

Many dislocations were found to be induced when GaAs chips for Gunn diodes were mounted on a heat sinking stud by a thermocompression bonding method. By introducing dislocations into epitaxial GaAs with a bending method, dislocations were confirmed to behave as acceptors in GaAs. Degradation or increase of the low field resistance of a Gunn diode by thermocompression bonding is considered to be due to induced dislocations.
Isotopic separation by photopredissociation
Authors: Yeung Edward S. , Moore C. Bradley
Published: January 2004

A monochromatic source may be used to excite individual isotopic lines in a well-resolved absorption spectrum for which the upper state is predissociated. Isotopic enrichment is thus achieved in the dissociation products, which may be stable molecules or may be chemically trapped if they are reactive. As an example, isotopic separation of hydrogen and deuterium is performed by exciting formaldehyde with a frequency-doubled ruby laser.
Field-ion-microscope studies of the interface between solid-liquid metals in vacuum
Authors: Utsumi T. , Nishikawa O.
Published: January 2004

An exploratory field-ion-microscope study of the interface between solid and liquid metals in vacuum is reported using a Ga–In–Sn alloy as the liquid metal. The result with tungsten was no surface atom rearrangement at the interface; with molybdenum, the formation of an alloy of unidentified crystal structure; with iridium, no alloy formation but dissolution of a part of the tip; and with platinum, complete dissolution of the tip.
Magnetomyography: magnetic fields around the human body produced by skeletal muscles
Authors: Cohen David , Givler Edward
Published: January 2004

Measurements of the magnetic fields from skeletal muscles, called magnetomyograms (MMG's), have been taken in a heavily shielded room with a superconducting magnetometer. These magnetic fields appear to be produced by the same currents in the volume conductor, associated with muscle action potentials, which also produce the surface electromyogram (EMG). Unlike the EMG, however, the MMG can readily detect slowly changing or direct currents. The MMG's, which were taken at locations near the elbow and the palm of the hand, are shown along with their frequency spectra.
Determination of the spatial distribution of deep centers from capacitance measurements of pn junctions
Authors: Zohta Yasuhito , Ohmura Yamichi
Published: January 2004

Effects of a spatial distribution of deep centers on the junction capacitance are reported for the first time. It is shown that the spatial distribution of deep centers can be calculated from capacitance data measured by both the capacitance-voltage method and the Copeland method, if their energy level is known or assumed. The theory is examined with the experiment on silicon p+n junctions irradiated with 300-kV protons. The analysis yields a value 0.40 eV below conduction band for the energy level of radiation-induced defects, as well as a distribution of the defects with depth.
Momentum transfer and plasma formation above a surface with a high-power CO2 laser
Authors: Pirri A.N. , Schlier R. , Northam D.
Published: January 2004

An experiment was performed to measure the total impulse transferred to a surface by a high-power pulsed 10.6-μ laser under atmospheric conditions, and also to determine the degree to which the observed plasma decouples the laser energy from the surface. Specific interest was directed toward conditions under which a ``radiation-driven detonation wave'' may form due to the presence of a surface. The momentum transferred in dyn sec/J decreases with an increase in the ratio of incident energy to spot area since a larger fraction of the energy is decoupled from the surface.
Vibration-to-vibration energy transfer in N2–CO
Authors: Zittel Paul F. , Moore C. Bradley
Published: January 2004

The rate of transfer of a vibrational quantum from N2 to CO has been measured at room temperature using a laser-excited vibrational fluorescence technique.
New electro-optic light valve device for image storage and processing
Authors: Grenot M. , Pergrale J. , Donjon J. , Marie G.
Published: January 2004

A new electro-optic light valve, based on the Pockels effect in a KD2PO4 crystal addressed by photoconduction, is described. At the present stage, the picture exhibits a resolution of 20 lp/mm (line pairs/mm), a very uniform contrast of 40/1, and an extensive grey scale; the writing time is less than 10 μsec. The device allows image addition and image subtraction and can be used as an input device in optical coherent processors.
Probing of acoustic shear wave radiation in surface wave devices
Authors: Ristic V.M. , Zuliani M. , Stegeman G. , Vella P.
Published: January 2004

Simultaneous Rayleigh and shear wave generation has been achieved using interdigital transducers on a yz LiNbO3 sample at a frequency of 104 MHz. A large-diameter laser beam of 5145-Å wavelength and 1-W cw power was transmitted through the sample and was modulated by two acoustic waves. The double-modulated laser beam causes fringes at the recording plane, which were used for an accurate determination of the shear wave velocity vs and of the shear wave acoustic radiation angle α into the crystal. It was found that vs = 3.547 ×103 m/sec for α = 14.3°. The shear wave conversion loss of the transducer was approximately 6 dB.
Optical waveguiding in proton-implanted GaAs
Authors: Garmire E. , Stoll H. , Yariv A. , Hunsperger R.G.
Published: January 2004

We have produced optical waveguides in n-type GaAs by implantation with 300-keV protons. The guiding is shown to be due to the elimination of charge carriers from the implanted region. Annealing of the waveguide leads to very large reductions in the 1.15-μ guided-wave absorption.
New ferroelectric compound SrTeO3
Authors: Yamada Tomoaki , Iwasaki Hiroshi
Published: January 2004

A synthetic compound SrTeO3 was discovered to exhibit ferroelectricity in the temperature range between 312 and 485°C. Small single crystals could be grown by the Kyropoulos method. The crystal belongs to the monoclinic system and its space group is C2/ c − C2 h6 at room temperature. A pronounced dielectric anomaly was observed along the b axis at 485°C. The value of the spontaneous polarization, obtained by the D-E hysteresis loops at 50 Hz, is 3.7 μC/cm2 at 312°C.
Differential I/V of heterostructure correlates with laser threshold
Authors: Rode D.L. , Dawson L.R.
Published: January 2004

We report detailed measurements of current (I) vs voltage (V) on double heterojunctions (AlxGa1−xAs–GaAs–AlyGa1−yAs) at very high injection levels which reveal nearly discontinuous ∂2V/∂I2 at currents ∼ 30% below lasing threshold. This behavior persists unchanged after the laser mirrors are destroyed. A similar breakpoint in ∂2V/∂I2 is found on nonlasing double heterostructures and correlates with the onset of intense infrared emission.
Electron micrographs of hologram cross sections
Authors: Akagi Motoo , Kaneko Tadao , Ishiba Tsutomu
Published: January 2004

The cross sections of both amplitude and phase holograms are observed by electron microscopy. Holograms were recorded on Kodak 649F and Scientia 14C75 sheet films by using a He–Ne laser beam (6328 Å). It is shown that the holograms are recorded throughout the whole thickness of the emulsion layer and the developed grains are enlarged by bleaching (about 1.5 times by length). This enlargement can be correlated with the thickness change of the emulsion layer during the chemical processing in making holograms.
Fabrication of single-crystal semiconductor optical waveguides by solid-state diffusion
Authors: Taylor H.F. , Martin W.E. , Hall D.B. , Smiley V.N.
Published: January 2004

Optical surface waveguides have been fabricated by diffusing selenium into single-crystal CdS substrates to produce graded-composition CdSxSe1−x crystals. Planar guides which confine a beam in one dimension and guides produced by masked diffusion capable of two-dimensional beam confinement have been obtained. Evidence of guiding of light from a HeNe laser is provided by photographs and by measurements of spatial intensity profiles. Losses are estimated to be 10–15 dB/cm for one-dimensional guides and 30–40 dB/cm for two-dimensional guides.
Magnesium gallate spinel: a substrate for the direct liquid-phase epitaxial growth of (Ga,Al)As
Authors: Scott B.A. , Nichols K.H. , Potemski R.M. , Woodall J.M.
Published: January 2004

The single-crystal growth of the cubic spinel, MgGa2O4, by the Czochralski technique is reported. Moreover, experiments are described in which this material is used as a substrate for the first direct (single-step) liquid-phase epitaxial growth of 〈111〉 (Ga,Al)As.
Radiation from a beam of modulated electrons. II
Authors: Becchi C. , Morpurgo G.
Published: January 2004

It is discussed in detail why a result by Van Zandt and an implication by Schwarz (that the magnitude of the Schwarz-Hora effect can be linear in the electron current) are incorrect. The large discrepancy noted in an earlier paper between the expected magnitude of the effect and the value which Schwarz claims to have measured thus persists.
Effect of uniaxial pressure on the threshold current of double-heterostructure GaAs lasers
Authors: Ripper J.E. , Patel Navin B. , Brosson P.
Published: January 2004

On application of uniaxial pressure perpendicular to the junction, the threshold current of GaAs double-heterostructure injection lasers at room temperature is observed to increase to a certain critical pressure P0, and then decrease with further increase in pressure. A flip of the polarization of laser light occurs at P0. This behavior can be explained using a model previously proposed to explain the reduction in threshold of homostructure GaAs lasers upon application of uniaxial pressure.
Dynamic scattering life in the nematic compound p-methoxybenzylidene-p′-amino phenyl acetate as influenced by current density
Authors: Sussman Alan
Published: January 2004

The time to failure of a compound exhibiting dynamic scattering, operated under dc excitation, is shown to be inversely proportional to current density. Two failure modes have been observed, both related to an anodic electrochemical reaction. Failure occurs in the compound p-methoxybenzylidene-p′-amino phenyl acetate (APAPA) after the passage of 1.2 × 106 C/mole through the operating cell. The quantity of charge passed through, in C/mole of cell material, is recommended as a figure of merit for materials which fail due to electrochemical processes.
Lateral spread of boron ions implanted in silicon
Authors: Akasaka Youichi , Horie Kazuo , Kawazu Satoru
Published: January 2004

The lateral spread of implanted ions is measured in boron-implanted silicon by junction delineation. The maximum lateral spread of a p-type region from a mask edge is about half the junction depth. Typical values are 0.4–0.6 μ in n-type substrates of 0.1 Ω cm at an implantation energy in the range 75–250 keV with the dose level of 1×1015/cm2, or at 150 keV with the dose in the range 1×1014–5×1015/cm2. These experimental values are well interpreted by the theory in which the lateral spread is expressed as a complementary error function with the standard deviation calculated by the LSS theory.
Stimulated parametric fluorescence induced by picosecond pump pulses
Authors: Rabson T.A. , Ruiz H.J. , Shah P.L. , Tittel F.K.
Published: January 2004

Stimulated parametric fluorescence emission tunable over the range from 0.96 to 1.16 μ has been obtained using a barium sodium niobate crystal pumped by a frequency-doubled and mode-locked Nd3+:glass laser. The pump radiation in the form of a train of picosecond pulses produced infrared parametric fluorescence pulses, less than 10 psec in duration and with average peak powers on the order of 300 W when pumped with a power density of 300 MW/cm2.
High-resolution spectroscopy using magnetic-field-tuned semiconductor lasers
Authors: Nill K.W. , Blum F.A. , Calawa A.R. , Harman T.C.
Published: January 2004

Tunable laser spectroscopy measurements on low-pressure gases have been performed using magnetic-field-tuned lead-salt semiconductor diode lasers in the 4- to 7-μm region. Use of magnetic field tuning in conjunction with the conventional current tuning is shown to significantly increase the versatility of diode lasers in high-resolution spectroscopy. Details of the tuning characteristics for fields up to 90 kG are presented.
A concept for the generation of reproducible and controllable giant pulses
Authors: Baues P. , Hundelshausen U.v. , Möckel P.
Published: January 2004

A YAG: Nd laser system is described which supplies giant pulses which are within 3% constant in shape and size and do not depend on the pump energy and the shape of the pumping pulses. A LiNbO3 crystal cut at the Brewster angle is used as a Q switch. Since the oscillation of the laser in the off state is used to open the Q switch, a definite inversion always occurs within the laser rod at the instant the switch opens that is due to the threshold of the off state and depends solely on the cavity characteristics. The height of the giant pulses is moreover easily controlled by varying the voltage applied to the LiNbO3 crystal.
Annealing study of ion-implanted silicon by photoelectromagnetic method
Authors: Inada Taroh , Ohnuki Yasuhide , Nishimura Hidetaroh
Published: January 2004

The photoelectromagnetic effect (PEM effect) on indium-implanted silicon was examined as a function of ion dose in the range 1014–1015 ions/cm2 and as a function of annealing up to 800°C. The experimental results indicated that the measurements of the PEM voltage can be utilized as a means of detecting changes in lattice ordering in ion-implanted silicon that were caused by the annealing treatment. Combining the results of the PEM voltage measurements with those of electron diffraction examinations, it was found that crystal reordering in In-implanted silicon by postannealing occurred from an inward part of the host crystal rather than from the ion-implanted surface.
Phase-matchable nonlinear optical interactions in periodic thin films
Authors: Somekh Sasson , Yariv Amnon
Published: January 2004

A proposal for a new method of phase matching in nonlinear optical interactions is made. A periodic perturbation of the surface of a thin-film waveguide generates space harmonics with new propagation constants which can be phase matched. An analysis of this proposal shows it to be particularly interesting for a class of thin-film nonlinear devices using the cubic optically isotropic semiconductors (such as GaAs, GaP, etc.) which possess high nonlinear optical coefficients but are not phase matchable by the conventional birefringent techniques.
Effect of charge-transfer acceptors on dynamic scattering in a nematic liquid crystal
Authors: Baise A.I. , Teucher I. , Labes M.M.
Published: January 2004

The addition of charge-transfer acceptors to a nematic liquid crystal at concentrations <0.1% has a profound effect on the voltage-transmission characteristics for dynamic scattering, reducing the threshold voltage by a factor of 2 for dc fields, but not appreciably altering the ac behavior. Charge-transfer bands in the visible may be introduced that depend on the concentration and nature of the acceptor molecule employed.
Acoustic-surface-wave convolver using nonlinear interaction in a coupled PZT-Si system
Authors: Yamanishi M. , Kawamura T. , Nakayama Y.
Published: January 2004

Efficient acoustic-surface-wave convolution, using 14.5-MHz Bleustein-Gulyaev waves, has been observed in a coupled PZT-Si system. It has been found that the magnitude of the phenomenological nonlinear coupling constant of the convolver was four times as large as that of the basal plane of PZT-8. The convolution output was controlled by the application of a voltage of several tens of volts.
Average energy to form electron-hole pairs in GaP diodes with alpha particles
Authors: Kobayashi T.
Published: January 2004

The energy required to form an electron-hole pair in gallium phosphide has been measured using GaP p-n junction diodes made from high-purity-level GaP materials. The values of εGaP for several GaP diodes for alpha particles ranged from 6.35 to 6.75 eV, with an average value of 6.54 ± 0.13 eV at 300°K. This value is smaller than that obtained by Goldstein and is very close to the value of 6.56 eV calculated from the experimental relationship ε = 2.596Eg + 0.714 (eV), which was derived previously from the experimental values of ε for Ge, Si, GaAs, and CdTe.
Convolution of signals using surface-wave delay lines
Authors: Das P. , Araghi M.N. , Wang W.C.
Published: January 2004

Detection of the convolution of two signals which is produced by the surface-wave nonlinearities is possible by employing several different methods. These methods, some of which are new and more efficient, are discussed, and a general explanation applicable to all cases is proposed.
Effect of magnetic field on current filament in gold-doped silicon
Authors: Homma K. , Kobayashi Y. , Fukami T.
Published: January 2004

The behavior of a current filament in a gold-doped p+-n Si diode was studied under a transverse magnetic field. The probe technique of electric potential was applied to measure the current distribution of the filament. By the action of the magnetic field, the filament was deformed and deflected toward one side of the diode. Moreover, a new ``filament instability'' which generates oscillation phenomena in the diode was observed.
Measurement of trapped-minority-carrier thermal emission rates from Au, Ag, and Co traps in silicon
Authors: Yau L.D. , Sah C.T.
Published: January 2004

A new technique for measuring thermal emission rates of trapped minority carriers is experimentally demonstrated in reverse-biased n+p silicon diodes doped with gold, silver, and cobalt. It makes use of a monochromatic light of a proper photon energy to partially fill the traps with minority carriers (electrons). After the light is turned off, the thermal emission rates of the minority carriers are observed. A unique feature is that the thermal emission rates for both the minority and majority carrier traps can be accurately determined in just one p-n junction, of either a p+n or n+p type.
NaYF4 : Yb,Er—an efficient upconversion phosphor
Authors: Menyuk N. , Dwight K. , Pierce J.W.
Published: January 2004

Studies of the infrared-pumped visible luminescence of NaYF4 : Yb, Er show it to have at least twice the visible output of YF3 : Yb, Er when pumped with a narrow-band excitation source at the optimum frequency. It is also free from saturation effects until very intense excitation levels are reached. The mechanism for red upconversion appears to change with increasing excitation from a two-step process to one involving a significant amount of three-step upconversion, which change is accompanied by an increase in the response time for visible emissions.
Study of spectral broadening in a filament of light
Authors: Wong George K.L. , Shen Y.R.
Published: January 2004

We have measured with nanosecond laser pulses the spectral broadening of light emitted from a filament under controlled input conditions. Our results are in semiquantitative agreement with predictions from the moving-focus model.
Gas breakdown in the laser as the limitation of pulsed high-pressure CO2 lasers
Authors: Berger Paul J. , Smith David C.
Published: January 2004

Gas breakdown, ionization of a gas by laser radiation, sets an upper limit on the operating pressure of pulsed CO2 lasers. The breakdown threshold decreases with increasing pressure, whereas the saturation energy of the laser increases with pressure. These two competing effects lead to the prediction of a maximum operating pressure above which the energy stored in the laser cannot be extracted without initiating gas breakdown. Gas-breakdown-threshold measurements have been made in typical laser mixtures, and breakdown has also been observed inside the laser cavity of an atmospheric-pressure CO2 laser. Based on these measurements and previously reported saturation measurements, the upper limit for efficient use of CO2 lasers is predicted to be in the range of 2–4 atm.
Thin film surface orientation for liquid crystals
Authors: Janning John L.
Published: January 2004

Vacuum-deposited films now replace the familiar ``rubbing'' process in substrate preparation for liquid-crystal cells. Films deposited at an angle provide an oriented surface for alignment of nematic liquid crystals far better than the well-known ``rubbed'' plate. The oblique deposit causes a film growth in a preferred direction, which results in a ``sympathetic alignment'' of the nematic liquid crystals when applied.
Epitaxial electro-optic mixed-crystal (NH4)xK1−xH2PO4 film waveguide
Authors: Ramaswamy V.
Published: January 2004

Observation of optical guidance in an epitaxial mixed-crystal film (NH4)xK1−xH2PO4 grown on a (100) KDP substrate is reported. The film thickness was ∼38 μ. The ordinary and extraordinary indices of the film for x=0.07 at 589.3 nm were nfo=1.5105 and nfe=1.4695. The difference in corresponding indices between the film and the substrate was 10−3. When the film waveguide was excited by a Gaussian He–Ne laser beam, the distribution of energy across the output face of the crystal confirmed one-dimensional guiding in the epitaxial film.
Like-sign asymmetric dislocations in zinc-blende structure
Authors: Abrahams M.S. , Blanc J. , Buiocchi C.J.
Published: January 2004

Symmetry considerations reveal that an asymmetry exists relative to orthogonal 60° dislocations of the same sign in zinc-blende structure. The effect of this asymmetry has been observed in compositionally graded crystals of In1−xGaxP and GaAs1−xPx grown from vapor phase. It is observed that the spatial arrangement of the two sets of misfit dislocations in an orthogonal array is different. In one 〈110〉 direction, the misfit dislocations tend to be uniformly distributed, while in the other 〈110〉 direction there is a marked tendency for periodic banding of the dislocations.
Thermoelectric analysis of transport in linear transition-metal organometallic compounds
Authors: McKenzie John W. , Wu Chen-ho , Bube Richard H.
Published: January 2004

Thermoelectric analysis of the electrical conductivity in Ir(CO3) Br and K2Pt(CN)4Cl0.3·xH2O as a function of temperature and atmosphere gives additional insight into the transport processes involved. The temperature independence of the thermoelectric power measured for Ir(CO3) Br indicates that the observed temperature dependence of conductivity is due to the mobility of the carriers and is consistent with a hopping model for conductivity. Two quite different electronic states of K2Pt(CN)4Cl0.3·xH2O are defined as (i) a high-conductivity hydrated state with x ≈ 2.6, which exhibits a small positive thermoelectric power, and (ii) a lower-conductivity dehydrated state with x ≈ 0, which exhibits a larger negative thermoelectric power. Log conductivity in the former state varies as 1/T1/2, whereas in the latter state log conductivity varies as 1/T.
Rh-doped LiNbO3 as an improved new material for reversible holographic storage
Authors: Ishida A. , Mikami O. , Miyazawa S. , Sumi M.
Published: January 2004

A poled single crystal of LiNbO3 doped with Rh as a new impurity is described in terms of its storage performance in producing high-efficiency simple phase holograms. Doping with Rh introduces a new absorption band peaking around 4880 Å, and dramatically improves the recording sensitivity, diffraction efficiency, erasing sensitivity, and persistence of holograms over the undoped crystal. Anomalous optical erasure, possibly due to self-enhancement of the hologram, is also observed in our doped crystal.
Direct measurement of flat-band voltage in MOS by infrared excitation
Authors: Yun B.H.
Published: January 2004

A photoexcitation technique for the direct measurement of metal-oxide-semiconductor (MOS) flat-band voltage is described. The principle consists of generating excess carriers in the semiconductor space-charge region by infrared pulses as a function of potential applied across the MOS capacitor and utilizing the fact that the current pulses induced in the external circuit become identically zero when the applied voltage is equal to the flat-band voltage. Experimental results are presented for MOS on silicon substrates.
Bulk recombination of charge carriers in polymer films: poly-N-vinylcarbazole complexed with trinitrofluorenone
Authors: Hughes R.C.
Published: January 2004

High concentrations of photocarriers have been produced in the bulk of a thin film of the photoconducting polymer poly-N-vinylcarbazole : trinitrofluorenone (PKV : TNF) by a Q-switched ruby laser, and the bulk (bimolecular) recombination of the charge carriers has been observed. The kinetics of recombination are in quantitative agreement with a theory originally developed by Langevin for the diffusion-controlled recombination of ions in high-pressure gases. The recombination rate constant is proportional to the carrier mobility, and despite the low carrier mobility the rate constant is as large as is found in many semiconductors.
Stimulated VUV emission in high-pressure xenon excited by high-current relativistic electron beams
Authors: Koehler H.A. , Ferderber L.J. , Redhead D.L. , Ebert P.J.
Published: January 2004

Vacuum ultraviolet (VUV) emission characteristics of xenon for pressures from 15 to 450 psi are presented. Stimulated emission was observed above 200 psi. Experiments were run both with and without mirrors. Without mirrors, the emission was 150 Å wide centered at 1700 Å, and the mean radiative lifetime was 2×10−8. The energy conversion efficiency was ∼ 20%. With mirrors above 200 psi the emission width narrowed to 17 Å centered at 1716 Å, and the output was highly directional. The pulse width narrowed from 50 to ∼ 3 nsec.
cw laser oscillation in singly ionized iodine
Authors: Piper J.A. , Collins G.J. , Webb C.E.
Published: January 2004

We have observed cw laser oscillation on ten transitions of singly ionized iodine in a He–I2 mixture using a multiple anode-hollow cathode laser tube of metal construction. Output characteristics as a function of helium pressure, iodine partial pressure, and discharge current have been investigated.
Experimental observation of the radial pattern of an ion sound wave parametrically excited in Tonks-Dattner resonance
Authors: Ikezawa Shunjiro , Okuda Takayoshi
Published: January 2004

The radial pattern of an ion sound wave in a mercury discharge tube where the ion sound wave is parametrically excited in Tonks-Dattner resonance is observed. The frequency of the HF (high-frequency) wave is chosen to be about one order lower than that in Stern's experiment so that the diameter of the tube can be large, by which means the detailed radial pattern of the wave can be obtained. The result qualitatively agrees with the theory predicted by Rosa and Allen-that is, it does not show the standing-wave pattern.