bluuebunny/crossref_metadata_2025 huggingface dataset:
Noise in Josephson point contacts with and without rf bias
Authors: Claassen J. H. , Taur Y. , Richards P. L.
Published: January 2004

Point contact Josephson junctions operated as microwave mixers at 36 GHz show conversion gain and lower noise than cooled Schottky barrier diodes in the same application. The noise in such junctions with and without rf bias is explored both experimentally and theoretically. The noise power is found to be about a factor 2 above the thermal noise in the resistively shunted junction model. In contrast to previous reports, the inclusion of a shot noise term in the theory for no rf bias overestimates the observed noise substantially.
Chemical vapor deposition of superconducting Nb3Ge having high transition temperatures
Authors: Braginski A. I. , Roland G. W.
Published: January 2004

Superconducting films of Nb3Ge have been deposited by chemical vapor deposition. Chloride vapors were produced in situ and reduced by hydrogen. The reactor used allowed surveying of phases with varying Nb/Ge ratio. The highest transition onset temperature was 21.7 K with a transition width of 0.4 K. It occurred near the Ge-richest boundary of the Nb3Ge phase.
Spatial dependence of the carrier lifetime in thin films of silicon on sapphire
Authors: Kranzer Ditmar
Published: January 2004

An experimental technique is described for determination of the generation carrier lifetime as a function of the distance of the insulator-semiconductor interface. This method is applied to thin films of silicon on sapphire nominally 1 μ thick and doped n type.
The complete base profile shape in a pushed-out diffused transistor analyzed by radiotracer methods
Authors: Jones C. L. , Willoughby A. F. W.
Published: January 2004

The first determination of the complete base profile shape in a pushed-out diffused transistor is reported. The effect of phosphorus emitter diffusion on a previously diffused gallium base has been monitored by radiotracer profiling using the isotope Ga67, and the phosphorus profile has been simultaneously measured by resistivity profiling. Definitive evidence is presented that the push-out effect is caused wholly by a real inward migration of base impurity atmos at a rate which is much enhanced over the normal migration rate. The profile shape of gallium after push-out shows a marked dip in concentration within the diffused emitter.
Optical striplines for integrated optical circuits in epitaxial GaAs
Authors: Blum F. A. , Shaw D. W. , Holton W. C.
Published: January 2004

Optical confinement has been observed in low-loss (<5 dB/cm) GaAs channel waveguides which are the optical analog of a microwave stripline.
Acoustic anharmonic properties of arsenic trisulfide glass
Authors: Rouvaen J. M. , Bridoux E. , Moriamez M. , Torguet R.
Published: January 2004

The usefulness of a material for nonlinear acoustic applications may be deduced from an anharmonic figure of merit. It is shown in this letter that materials well suited for acousto-optic applications are also acoustically highly nonlinear.
Are unexpected bulk waves produced by surface wave transducers?
Authors: Weinert R. W. , Emtage P. R. , de Klerk J. , Daniel Michael R.
Published: January 2004

It was recently reported that a surface wave transducer could produce a beam of bulk waves whose tangential wave number was twice the fundamental wave number of the transducer; the wave numbers in the transducer's electric field are odd multiples of the fundamental. In this investigation it is found that the extra beam comes from mode conversion of rays reflected at the ends of the sample; the beam is not directly generated by the transducer.
Hysteresis in the deformation of nematic liquid crystal layers with homeotropic orientation
Authors: Deuling H. J. , Helfrich W.
Published: January 2004

An electric field deforming a nematic slab becomes inhomogeneous because of dielectric or conductive anisotropy. An investigation of the latter regime indicates that the Fréedericksz transition first becomes steeper and finally gives way to hysteresis as the conductive anisotropy is increased.
Electro-optic diffraction modulator using out-diffused waveguiding layer in LiNbO3
Authors: Noda Juichi , Uchida Naoya , Saku Tadashi
Published: January 2004

A high-speed Bragg-type electro-optic modulator with modified interdigital electrodes has been constructed using a Li out-diffused waveguide layer in LiNbO3. The thickness of the layer is about 7 μm and only two modes, TE0 and TE1, are supported. For the TE0 mode, a maximum modulation index of about 70% is obtained up to 900 MHz with an applied voltage of 18 V.
A physical model on the initiation of atmospheric-pressure glow discharges
Authors: Palmer A. Jay
Published: January 2004

A model on the preionization requirements for initiating a volume-stabilized glow discharge is proposed. The basic requirement of the model is that the preionized electron density be large enough to cause appreciable spatial overlap of the primary avalanches and consequent smoothing of space-charge field gradients at the stage when streamer formation would otherwise occur. A minimum required preionization electron density of ∼ 104 cm−3 is predicted for a typical CO2 TEA laser discharge and is consistent with experimental observations.
Operation of a 15-atm electron-beam-controlled CO2 laser
Authors: Harris N. W. , O'Neill F. , Whitney W. T.
Published: January 2004

We describe the operation of a 15-atm electron-beam-controlled CO2 laser. Stable glow discharges have been sustained in the high-pressure He:CO2:N2 mixtures for 0.5 μsec using an electron-beam current of ≲ 1.5 A/cm2. A small-signal gain ∼ 0.052 cm−1 has been measured in a 70%(He):25%(CO2):5%(N2) mixture for an energy input to the gas ∼ 115 J/l atm. We have obtained a laser output energy of 1.2 J from a volume of 22 cm3 for an over-all efficiency of 2.5%.
Multiphoton photorefractive processes for optical storage in LiNbO3
Authors: von der Linde D. , Glass A. M. , Rodgers K. F.
Published: January 2004

Permanent reversible changes of the refractive index of pure and doped LiNbO3 have been obtained by multiphoton absorption. Greatly increased sensitivity over the linear process enables holograms to be recorded even in high-purity LiNbO3, with a diffraction efficiency of 25% with less than 0.4 J/cm2. These holograms can be read nondestructively, eliminating the need for fixing processes while the versatility of optical erasure is maintained.
Palladium silicide formation observed by Auger electron spectroscopy
Authors: Robinson G. Y.
Published: January 2004

The growth kinetics and composition of thin films of Pd2Si on <111> single-crystal Si was observed by combining Auger electron spectroscopy with the in situ sputter etching. The characteristic Auger spectrum for Pd2Si was measured and separately identified by x-ray diffraction analysis. In-depth composition profiles indicated that a Si-rich region exists near the silicide/silicon interface during the diffusion-limited Pd2Si formation.
Coherent optical pulse reshaping in a resonant molecular absorber
Authors: Hamadani S. M. , Goldhar J. , Kurnit N. A. , Javan A.
Published: January 2004

The coherent reshaping of short-duration (2–40 nsec) N2O laser pulses in a resonant NH3 absorber is studied for a variable number of absorption lengths (αl ≤ 14). For small-area square pulses, the reshaping can produce subnanosecond pulses at the leading and trailing edges. A rapid phase reversal gives rise to amplification for times comparable to the transverse relaxation time. Zero-degree pulses [∫−∞∞E(z,t) d t=0] are observed to propagate with enhanced transmission for both short-duration low-intensity pulses and longer pulses of intensity sufficient to enable observation of optical nutation effects.
Local control of uniaxial anisotropy in LPE bubble garnet films
Authors: Gyorgy E. M. , LeCraw R. C. , Blank S. L. , Wolfe R.
Published: January 2004

Local control of the growth-induced anisotropy in LPE bubble garnet films can be obtained by masking part of the film with a layer of epitaxial Gd3Ga5O12 and annealing at elevated temperatures (∼ 1200 °C) in a nitrogen atmosphere for approximately 1 h. In the regions exposed to nitrogen, the introduction of oxygen vacancies accelerates the reduction of Ku by the randomizing of the rare-earth ion distribution.
Energy density and time constant of heavy-ion-induced elastic-collision spikes in solids
Authors: Sigmund Peter
Published: January 2004

Spike effects may influence sputtering and disordering of ion-bombarded solids in the case of a high density of energy deposition and long lifetime. We estimate both quantities and find very pronounced variations with the atomic numbers of the projectile ion and target and the bombarding energy. The predicted energy range where sputtering should be affected is consistent with observed anomalies in the measured yield.
Real-time convolution using acousto-optic diffraction from surface waves
Authors: Kramer C. J. , Araghi M. N. , Das P.
Published: January 2004

Convolution of two signals has been obtained in real time using the efficient diffraction of laser light from acoustic surface waves. Two pulse-modulated 45-MHz surface waves are launched from the two ends of a surface wave delay line. Laser light enters the delay line from one side, interacts with two oppositely directed parallel acoustic beams along their widths, and exits from the other side. The diffracted light, after an optical Fourier transformation, is incident on a photodiode which produces an electrical output containing the desired convolution signal. With the present 5-μsec interaction length and 9-MHz transducer bandwidth, the time-bandwidth product is 45.
Charge storage in SiO2 under low-energy electron bombardment
Authors: Fanet J. M. , Poirier R.
Published: January 2004

Low-energy (≃ 10 eV) electron bombardment on an SiO2 layer gives rise to strong trapping at the surface and to a positive space-charge build-up near the Si–SiO2 interface. The density, the capture cross section, and the energy level of the traps have been evaluated using, respectively, the constant current charging process and the quantum yield of vacuum photoemission versus wavelength.
A monolithic zinc-oxide-on-silicon convolver
Authors: Khuri-Yakub B. T. , Kino G. S.
Published: January 2004

A monolithic convolver using rf-sputtered zinc oxide deposited on silicon was constructed and operated at a center frequency of 120 MHz. The electronic efficiency obtained with this device F = Pout/Pin1Pin2, using 100-Ω cm silicon, was −70 dB m. This corresponds to an input-output efficiency of approximately −50 dB with a 20-dB m reference signal. These results agreed well with our theoretical expectations for the device. The theory predicts that with a properly optimized device, the electronic efficiency F can be of the order of −50 dB m.
Proton emission from microinstabilities in an electron-beam diode
Authors: Johnson David J. , Kerns John R.
Published: January 2004

The radial proton emission from a 5-MV 50-kA electron-beam diode with polyethylene anode has been spatially and spectrally measured with pinhole cameras and ion-sensitive vacuum diode detectors. The spatial measurements indicate that the protons originate from electron-beam pinches less than 200 μm in diameter. The proton spectrum measured between 80 keV and 3 MeV is in qualitative agreement with published data for a computer simulation of proton acceleration via the relativistic electron-ion two-stream instability in a tightly pinched electron beam.
Photovoltaic short-circuit minority carrier injection
Authors: Berry W. B.
Published: January 2004

Short-circuit capacitance data, for solar cells with base resistivities in the range 0.5–90 Ω cm, indicate a junction capacitance injected carrier concentration of the order 1014 cm−3 at photovoltaic current densities of 25 mA/cm2. This short-circuit injected carrier concentration, which is usually assumed to be zero, is nine orders of magnitude greater than the equilibrium concentration. This condition is explained in terms of an expanded interpretation of the Shockley injection relation where the chemical potential K of the electrochemical potential, μ = K−eV, dominates injection rather than the electrostatic potential V.
Epitaxial silicon p-n junctions on polycrystalline ``ribbon'' substrates
Authors: Kressel H. , Robinson P. , McFarlane S. H. , D'Aiello R. V. , Dalal V. L.
Published: January 2004

Silicon epitaxial layers have been deposited on polycrystalline silicon ``ribbon'' substrates. It is shown that the epitaxial layer is structurally much superior to the substrate material. Good quality p-n junctions have been epitaxially grown on these ribbons with reasonable values of minority carrier lifetime and saturation current density, but variations are observed related to structural imperfections.
Relative cross section and depolarization of NOCI
Authors: Hoell J. M. , Wade W. R.
Published: January 2004

The Raman scattering cross section of NOCl at a Raman shift of 334.4 ± 1.6 cm−1 is measured relative to the N2 Raman cross section. At 4880 Å, σNOCl/σN2 = 0.9 ± 0.1. An upper limit of 0.08 is also reported for depolarization ratio of the NOCl Raman line.
Transport coefficients of InAs epilayers
Authors: Wieder H. H.
Published: January 2004

Heteroepitaxially grown single-crystal InAs layers exhibit anomalies in the magnetic field dependence of their Hall coefficients, their magnetoresistance, and the temperature dependence of their electron mobilities. These are attributed to a degenerate surface accumulation of electrons and are interpreted in terms of a two-layer model, one with bulklike and the other with surfacelike charge carrier transport coefficients.
Selectively etched diffraction gratings in GaAs
Authors: Comerford L. , Zory P.
Published: January 2004

Selective etching techniques are described which have been utilized to fabricate V-groove diffraction gratings with spatial frequencies greater than 4000 lines/mm in {100} surfaces of GaAs.
A novel GaAs avalanche photodiode
Authors: Piqueras J. , Muñoz E.
Published: January 2004

A GaAs metal-semi-insulating-p-n+ structure is described as a novel reach-through avalanche photodiode. The p and n+ layers are simultaneously obtained by heat treatment and liquid-phase epitaxy. The high field at the p - n+ depletion layer allows one to reach multiplication factors close to 104 without avalanche breakdown. Photoinjected electrons from the metal barrier can extend the photodetection range up to 1.6 μm for Sn Schottky barriers.
Limit pulses in passive nonlinear absorbers
Authors: Lee C. T.
Published: January 2004

We reinvestigate the propagation of coherent pulses in absorbers with nonlinear refractive index. We show that a term neglected by previous authors places an upper limit on the attainable field strength in steady-state pulses. In ruby with a Cr3+ doping density of 1017 cm−3, for example, this limit is less than 2×106 V/cm.
GaAs IMPATT diodes prepared by molecular beam epitaxy
Authors: Cho A. Y. , Dunn C. N. , Kuvas R. L. , Schroeder W. E.
Published: January 2004

The performance of GaAs IMPATT diodes with a low-high-low doping structure prepared by molecular beam epitaxy (MBE) is described. Measured small-signal noise and high-level power-noise performance compare favorably to corresponding results for flat-doping-profile diodes. At 11 GHz a noise measure of 44 dB was obtained with 2.8-W power output. The concomitant efficiency was 18%.
Nature of optically induced defects in Ga1−xAlxAs–GaAs double-heterojunction laser structures
Authors: Petroff P. , Johnston W. D. , Hartman R. L.
Published: January 2004

It is shown by transmission electron microscopy (TEM) investigation that the dark line defect (DLD) structure induced by optical pumping of undoped Ga1−xAlxAs–GaAs double-heterostructure (DH) laser material is identical to the DLD's which develop during laser diode operation of devices fabricated from similar p-n structure material. This confirms the DLD generation, and subsequent failure of cw laser diodes can be a growth-related property of Ga1−xAlxAs–GaAs DH laser material and is not necessarily associated with p-n junction dopants or contact metallization technology.
Magnesium and zinc ion implantation into sulfur-doped GaP
Authors: Inada Taroh , Ohnuki Yashuhide
Published: January 2004

Electrical conduction type conversion was achieved by implanting either 15-keV Mg or Zn ions into n-type GaP substrates at room temperature and by subsequent annealing at 900°C. The p-n junction formed by the Zn implant lay at about 12.2 μm beneath the implanted surface and this depth was approximately 120 times deeper than that formed by the Mg implantation. For higher-temperature annealing, diffusion played a predominant role in the final atom location of Zn implanted in GaP, but that of Mg was not so affected. Hall mobility of holes was found to be approximately 28 cm2/V sec at room temperature in both p-type layers formed by Mg and Zn implantations. In the Zn-implanted samples, the room-temperature hole concentration, determined from the Hall coefficient, was found to exceed the Zn concentration expected from ion dose.
New phenomena on drain-to-source breakdown voltage of n-channel FET
Authors: Tsujide T.
Published: January 2004

Drain-to-source avalanche breakdown voltage which continues to increase gradually (walkout) with increasing drain voltage turns back instantaneously and negative resistance characteristics appear in the drain current-vs-drain voltage curve when the drain avalanche current exceeds a critical value. These phenomena can possibly be attributed to turn on of the avalanche-current-induced n+p n+ bipolar transistor operation. Further the model postulates electron injection and neutralization of holes trapped during walkout.
Dynamic model of high-pressure rare-gas excimer lasers
Authors: Werner C. W. , George E. V. , Hoff P. W. , Rhodes C. K.
Published: January 2004

The dynamic behavior of the high-pressure rare-gas VUV excimer systems is examined. It is found that the collisional coupling of the excited singlet and triplet manifolds in combination with the losses arising from photoionization play a vital role in determining the over-all performance. The proposed mechanisms provide a unified description of both the pressure dependence of the stimulated output and the observed pressure shift of the stimulated spectrum in xenon. Numerical values of the relevant parameters are given.
Phase-matched second-harmonic generation in GaAs optical waveguides by focused laser beams
Authors: van der Ziel J. P. , Miller R. C. , Logan R. A. , Nordland W. A. , Mikulyak R. M.
Published: January 2004

Using a tunable parametric oscillator operating near 2 μm, we have observed second-harmonic generation in a GaAs double-heterostructure waveguide in the region of phase matching. The harmonic intensity is strongly peaked when the guide propagation constants of the TE (m=0) fundamental and TM (m=2) harmonic are equal. Away from phase matching, the characteristic effects of strong focusing in the plane of the guide are observed. These are the one-dimensional analogs of the harmonic generation effects observed using two-dimensional focused laser beams.
Field dependence of the wall width and wall energy of compensation walls
Authors: Hansen P.
Published: January 2004

The influence of external magnetic fields on the energy and width of compensation walls in ferrimagnetic garnets of nonuniform magnetization has been investigated. Solutions for the angle between the direction of the applied magnetic field normal to the film plane and the magnetization in the wall have been obtained numerically where both the uniaxial and the cubic anisotropies were taken into account. The wall energy is shown to increase and the wall width to decrease with increasing magnetic field.
Velocity scatter in magnetic bubble motion
Authors: Josephs Richard M.
Published: January 2004

Measurements of bubble domain translational velocities using the transport technique are described. The dependence of the velocity on drive field has been determined using the measured spatial dependence of the velocity and the calculated spatial variation of the drive field. This is illustrated for an ion-implanted epitaxial film of Y2.4Eu0.6Ga1.2Fe3.8O12. Increased scatter in the velocity data occurs under conditions in which the bubble may run out. This demonstrates that the familiar elliptic instability suffices to explain the observed velocity scatter and that the more complex mechanism of ``dynamic conversion'' is not required.
Performance of 6-m 1300-MHz superconducting niobium accelerator structures
Authors: Turneaure J. P. , Schwettman H. A. , Schwarz H. D. , McAshan M. S.
Published: January 2004

The design, manufacture, and performance of several 6-m-long 1300-MHz superconducting niobium accelerator structures, which are part of the Stanford superconducting accelerator, are briefly described. In these standing-wave accelerator structures, we have achieved cw energy gradients as high as 3.8 MeV/m and unloaded Q's as high as 6.9×109 measured at 3.0 MeV/m and 1.9 K. In addition, electron-beam currents up to 5000 μA have been accelerated through the structure without exciting beam-breakup modes.
Integrated circuits as viewed with an acoustic microscope
Authors: Lemons R. A. , Quate C. F.
Published: January 2004

The images of a high-frequency bipolar transistor obtained with an acoustic microscope are compared with those of a differential interference optical microscope and a scanning electron microscope in order to illustrate that the acoustic microscope can be used in a reflection-type mode to obtain quality pictures of a surface containing integrated circuits. The frequency of the acoustic beam is 600 MHz and the resolution is near 2 μ.
Damage-induced microdomains in LiTaO3
Authors: Venables J. D.
Published: January 2004

Thin wafers of LiTaO3 prepared from fully poled boules by mechanical cutting and polishing techniques have been found to contain defects at high concentrations (up to 107/cm2). Examination of these wafers by optical and electron microscope techniques indicates that the defects are cylindrical domains 1–3 μm in diameter, within which the ferroelectric axis is inverted relative to the surrounding material. These inverted domains appear to have nucleated at screw dislocations, b∥ <0001>, which are observed near the axis of each domain. The results have implications for many applications of LiTaO3, because such multidomain configurations may contribute to undesirable optical scattering, Barkhausen noise, or degraded pyroelectric response. It is suggested also that the permanent optical damage generated in LiTaO3 by intense laser radiation may arise in part by the nucleation of similar inverted domains at dislocations generated through the action of large thermal stresses.
Wraparound ASW delay line with lens guidance and monolithic amplification
Authors: Henaff Jeannine , Pirio Francis , Sinou Marc , Feldmann Michel , Le Contellec Michel
Published: January 2004

A wraparound acoustic surface wave (ASW) delay line incorporating a periodical Δν/ν lens guiding structure and a monolithic InSb amplifier is described. Normal mode computation accounts for parabolic anisotropy. Experimental results on a 120-MHz recirculating LiNbO3 delay line are reported.
Implosion of an unneutralized drifting relativistic electron beam
Authors: Friedman M. , Vitkovitsky I. M.
Published: January 2004

A hollow relativistic electron beam, drifting in vacuum, can be made to implode radially when a grounded conductor is placed on the beam axis. The collapse is the result of the change in the direction of the electric field relative to that of a freely propagating beam. The entire energy content of the collapsed beam is dissipated in the conductor.
Surface waves and grating-tuned photocathodes
Authors: Endriz J. G.
Published: January 2004

Deposition of an Sl– [Ag–O–Cs] type photocathode onto a diffraction grating substrate has been shown to produce a photoemitter which provides resonant coupling to surface waves and associated significant enhancement in quantum efficiency at preselected frequencies for specified light angle of incidence.
Analysis of α relaxation in polymers by asymmetrical distribution functions of relaxation times
Authors: Vanderschueren J.
Published: January 2004

The distribution function of relaxation times for the α dispersion in polycarbonate has been calculated from measurements of thermally stimulated discharge currents. This function can be adequately described by the empirical expression of Havriliak and Negami, first derived from the complex plane analysis of ac dielectric data. The values of the distribution parameters obtained from the two types of measurements are in excellent agreement.
Microwave modulation of CO2 lasers in GaAs optical waveguides
Authors: Cheo P. K. , Gilden M.
Published: January 2004

Sideband power has been generated at frequencies offset approximately 10 GHz from a CO2 laser line, P(20)00°1→10°0, in a thin slab of GaAs. Efficent nonlinear interaction was accomplished by having the thin slab serve as both an optical waveguide and a microwave minigap ridge waveguide. With a 20-W microwave signal applied to a 30-μm-thick optical waveguide contained in a 0.9-cm-long ridge section, about 0.4% laser power has been transferred into the sidebands, consistent with the theory.
Multi-kilojoule HF laser using intense-electron-beam initiation of H2–F2 mixtures
Authors: Gerber R. A. , Patterson E. L. , Blair L. S. , Greiner N. R.
Published: January 2004

We report here the results of an HF-laser experiment in which an intense electron beam is used to initiate high-pressure room-temperature H2/F2 mixtures. The maximum laser energy was 2.3 kJ in a 35-nsec (FWHM) pulse with a mixture of 360-Torr F2, 140-Torr O2, 100-Torr SF6, and 100-Torr H2. Electrical efficiency for the laser was as high as 200%. The maximum chemical efficiency was 5.2%.
Space and time resolved gain measurements of a uv-sustained CO2 laser
Authors: Clark W. M. , Lind R. C.
Published: January 2004

Laser gain measurements at 10.6 μm are presented for a 2.5×5×50-cm high-pressure uv-sustained discharge in a CO2:N2:He:tri-n -propylamine gas mixture. The spatial variation of the gain, with a resolution of a 1.5-mm-diam spot, is discussed. The temporal behavior of the gain is shown to be influenced by the uv-induced photoionization, an acoustical disturbance generated by the uv source arcs, and by photoemission and collisional ionization effects near the solid electrode.
GaAs–Alx Ga1−x As double-heterostructure lasers prepared by molecular-beam epitaxy
Authors: Cho A. Y. , Casey H. C.
Published: January 2004

GaAs–Alx Ga1−x As double-heterostructure (DH) lasers that exhibit laser properties similar to DH lasers prepared by liquid-phase epitaxy have been prepared by molecular-beam epitaxy. For a structure with a 0.53-μ-thick active layer, the as-grown threshold current density at room temperature was 3.5×104 A/cm2, but by annealing the threshold was reduced to 4.0×103 A/cm2.
Residual disorder in Si from oxygen recoils in annealed ``through-oxide'' arsenic implants
Authors: Chu W. K. , Müller H. , Mayer J. W. , Sigmon T. W.
Published: January 2004

Channeling effect measurements were used to evaluate the residual damage in Si after 1000 °C anneal for high-dose (5×1015−2×1016 cm−2) As implantations through oxide layers. For these implantations the amount of damage after anneal increases with As dose and oxide thickness. This residual damage effect was simulated by oxygen implants into Si. We conclude that oxygen recoils are responsible for the disorder found in through-oxide implants and for defects found at the periphery of oxide cuts used as implantations masks.
Generation and detection of 150-psec mode-locked pulses from a multi-atmosphere CO2 laser
Authors: Alcock A. J. , Walker A. C.
Published: January 2004

Mode-locked operation of a uv-preionized TE CO2 laser has been investigated at pressures in the 10–15-atm range. By upconverting the output to 0.96 μm and recording it with a streak camera it has been shown that pulses of duration less than 150 psec can be generated using p-type Ge saturable absorbers.
Generation of subnanosecond CO2 laser pulses at 10.6 μm by pulse compression techniques
Authors: Feldman B. J. , Figueira J. F.
Published: January 2004

The results of an investigation of the time evolution of a mode-locked pulse produced by a CO2 laser passively mode locked with an In-doped Ge bleachable absorber are presented. The observed pulse shortening is explained by a simple theory of pulse compression due to the saturable absorber. Pulse durations as short as 400 ps are observed.
Gigahertz tunable waveguide CO2 laser
Authors: Abrams R. L.
Published: January 2004

A sealed-off cw waveguide CO2 laser has been continuously tuned over 1.2 GHz on a single transition at 10.6 μm. The laser consists of a 9.5 cm×1.0 mm square discharge tube fabricated from polished BeO slabs. Line selection is achieved with a diffraction grating and tuning is accomplished by piezoelectric control of the resonator length.
Traveling-wave gas laser
Authors: Faxvog F. R. , Gara A. D.
Published: January 2004

The ratio of the clockwise to counterclockwise intensities in a multimode HeNe ring laser was measured as the strength of unidirectional coupling between the two intensities was varied. These results are compared to calculations based on a gain saturation with field coupling model which indicates that intensity ratios >102 are possible. With the addition of an etalon in the laser cavity, stable single-mode operation is observed.
Amplification by injection locking of a Josephson oscillator
Authors: Stancampiano C. V. , Shapiro Sidney
Published: January 2004

Josephson oscillations near 9 GHz, produced by a point-contact junction mounted in a coaxial resonator and biased onto the cavity-induced step in its V-I curve, have been pulled in frequency and phase locked by a weak injected signal at a nearby frequency. The resulting output was at the signal frequency and had the narrow bandwidth and frequency stability of the input but the power level of the Josephson oscillations. Maximum gain of 51 dB was achieved for an input of 10−16 W.
Critical current density of a superconducting copper-base alloy containing Nb3Sn filaments
Authors: Tsuei C. C. , Suenaga M. , Sampson W. B.
Published: January 2004

The critical current density Jc of 0.25-mm Cu88.5Nb10.0Sn1.5 and Cu83.5Nb15.0Sn1.5 wires has been measured at 4.2 °K as a function of magnetic field H up to 100 kG. A typical value of Jc at H = 0 is ∼105 A/cm2 indicating that the critical current density of the Nb3Sn filaments is probably of the order of 106 A/cm2. Mechanical deformation such as bending some of the wire samples around a 1/2-in.-diam mandrel does not produce any significant degradation of Jc at H =40 kOe.
Tunable acousto-optic filter utilizing acoustic beam walkoff in crystal quartz
Authors: Chang I. C.
Published: January 2004

A new configuration of a tunable acousto-optic filter utilizing acoustic beam walkoff in crystal quartz is described. By changing the acoustic frequency from 54 to 175 MHz, tuning of optical wavelength from about 650 to 250 nm is obtained in a single filter.
Interior-surface acoustic waveguiding in capillaries
Authors: Rosenberg Robert L. , Schmidt R. V. , Coldren L. A.
Published: January 2004

Capillary tubing, used as a waveguide for surface acoustic waves confined to the interior surface, is shown to be a guiding structure that has a number of properties useful for long-delay-line applications. Very clean rf pulse transmission has been achieved, with spurious bulk modes stripped away by absorption at the outer surface. Low dispersion is available with bore diameters of a few Rayleigh wavelengths. In a fused silica structure flame-drawn to a half-meter length, the propagation loss was experimentally found to be limited by material bulk attenuation constants.
Deflection of atomic beams by resonance radiation using stimulated emission
Authors: Nebenzahl I. , Szöke A.
Published: January 2004

A new method is presented for the deflection of atomic and molecular beams by momentum transfer from resonantly absorbed and reemitted electromagnetic radiation. The method, which uses adiabatic rapid passage by chirped optical pulses, is capable of high energy efficiency. It can be used for isotope separation.
Large refractive index change induced by ion implantation in lithium niobate
Authors: Wei David T. Y. , Lee William W. , Bloom Louis R.
Published: January 2004

Large but negative refractive index change (∼ 10% at 632.8-nm line) is observed in several lithium niobate samples, each occurring in a thin layer induced by implantation of argon or neon ions. Implantation energy is 60 kV and the ion dose is 1016 cm−2 or more in each sample. Mechanisms causing the refractive index change and possible applications for integrated optics are discussed.
Migration of Mo atoms across Mo–Si interface induced by Ar+ ion bombardment
Authors: Nishi H. , Sakurai T. , Akamatsu T. , Furuya T.
Published: January 2004

Backscattering analysis is used to investigate the effect of 150-keV Ar ion bombardment on Mo thin films evaporated on silicon. Ar ion bombardment induces the migration of Mo atoms into the underlying substrate. These migration phenomena are caused mainly by an atomic recoil process, and depend on implanted ion dose and on film thickness. These phenomena are also affected by the peculiarity of the Mo–Si interface. The migration of Mo atoms occurs most noticeably at a thickness of 450±50 Å, where about five Mo atoms for every incident Ar ion are introduced.
Efficient uv generation at 3547 Å in RDP
Authors: Kato K.
Published: January 2004

The efficient generation of uv radiation at 3547 Å has been achieved in rubidium dihydrogen phosphate (RDP) through frequency mixing of the fundamental and second harmonic radiation of a Nd:YAG laser. An over-all peak power conversion efficiency of 21% was obtained for the experimental conditions described, thus demonstrating the attractiveness of RDP for frequency conversion applications.
Simultaneous measurement of absorption and scattering losses in bulk glass and optical fibers by a microcalorimetric method
Authors: Zaganiaris Alcibiade
Published: January 2004

When light is launched into either an optical fiber or a bulk glass rod, discrimination of scattered and absorbed energies is possible through the different thermokinetics of these phenomena. The design and performance of a differential calorimetric arrangement are presented and simultaneous measurements of the various loss coefficients are reported. At the present time, sensitivity is of the order of 1 dB/km and can be further improved.
Magnetic anisotropy in Pb-substituted Eu3 Fe5 O12 films
Authors: Plaskett T. S. , Klokholm E. , Cronemeyer D. C. , Yin P. C. , Blum S. E.
Published: January 2004

A large uniaxial magnetic anisotropy has been observed in (100) and (111) Pb-substituted Eu3 Fe5 O12 garnet films grown by the LPE technique from PbO:B2O3 fluxes. For a Pb content of about 5.0 wt% the uniaxial anisotropy was 1.9×105 erg/cm3 in films of (100) orientation and 0.5 × 105 erg/cm3 for (111) film orientations. This uniaxial anisotropy is shown to be induced by the Pb and is similar to the growth-induced anisotropy observed in mixed iron garnets.
A surface acoustic wave planar resonator employing an interdigital electrode transducer
Authors: Lakin K. M. , Joseph T. , Penunuri D.
Published: January 2004

A surface acoustic wave planar resonator is described in theory and experiment. The resonance is due to energy storage within an interdigital transducer. Experimental results are reported for a one hundred finger pair double electrode transducer on YZ LiNbO3 which exhibited a resonance Q of 1900 at 34 MHz. The resonator is unique in that the resonant frequency is not determined by material dimensions and many such devices can be fabricated upon a common substrate.
Extended dislocations in GaAs0.7P0.3
Authors: Mader S. , Blakeslee A. E.
Published: January 2004

Misfit dislocations in epitaxially grown layers of GaAs1−xPx with a lattice constant gradient were examined by weak beam TEM. They are dissociated into partial dislocations and in specimens with (113) growth planes they form networks of extended and contracted nodes on (111) planes. The dissociation corresponds to an intrinsic stacking fault energy of 43 erg/cm2 for GaAs0.7P0.3.
Rayleigh wave guidance using anisotropic topographic structures
Authors: Coldren L. A.
Published: January 2004

A new type of topographic acoustic surface waveguide which uses substrate anisotropy is described. In this guide the velocity reduction at the center of a hump or depression on the substrate is primarily due to the change in crystal cut rather than a reduction in material constraint as in other topographic guides. Experimental results obtained on the (001) apex of a 110 axis Bi12GeO20 rod are in good agreement with the predictions of a ``lenslike media'' theory based on parabolically approximated wave surfaces.
Two-photon resonantly enhanced self-defocusing in Cs vapor at 1.06 μ
Authors: Lehmberg R. H. , Reintjes J. , Eckardt R. C.
Published: January 2004

The electronic nonlinear refractive index in Cs vapor at 1.06 μ is shown to be negative and to consist of two distinct contributions. One of these contributions arises from a two-photon resonance in the susceptibility and can be made comparable in magnitude to the positive n2 in laser glass. The other term arises from population redistributions between the ground and first excited state. We present measurements of self-defocusing of a single pulse from a Nd: YAG mode-locked laser that are in agreement with the theoretical predictions.
Stimulated cyclotron resonance scattering and production of powerful submillimeter radiation
Authors: Sprangle P. , Granatstein V. L.
Published: January 2004

Interaction of a high-frequency electromagnetic pump wave with a magnetized plasma is analyzed. Enhanced growth rates for parametric instability are found near cyclotron resonance. The result implies that tunable high-power submillimeter sources could be developed using intense relativistic electron beams.
Observation of subgrain boundaries and dislocations by neutron diffraction topography
Authors: Schlenker M. , Baruchel J. , Pétroff J. F. , Yelon W. B.
Published: January 2004

We have improved the resolution of neutron diffraction topography by working with a low-divergence primary beam from a neutron guide tube and using an almost perfect monochromator. As a result, we have obtained neutron topographs revealing, although with a resolution still very inferior to that of x-ray topography, subgrain boundaries and inclusions in a Fe-2.5 wt% Si single crystal, as well as some individual dislocations in a germanium single crystal. Their contrast is compared with that of x-ray topographs of the same specimens and discussed.
Phase-matched guided optical second harmonic wave generation in oriented ZnS polycrystalline thin-film waveguides
Authors: Ito Hiromasa , Uesugi Naoshi , Inaba Humio
Published: January 2004

The first experimental verification of phase-matched SHG was performed in the polycrystalline ZnS thin-film waveguide deposited on a BK-7 glass substrate. The complete phase-matching between the TE1 mode at the fundamental frequency of 1.054 μm and the TM4 mode at its second harmonic wave was realized by using a tunable optical parametric oscillator. The interaction length estimated from the tuning curve for the phase matching was about 35 μm and the output harmonic power was of the order of milliwatts at 300-W fundamental input under the phase-matched condition.
Coherent anti-Stokes Raman spectroscopy
Authors: Begley R. F. , Harvey A. B. , Byer R. L.
Published: January 2004

Coherent anti-Stokes Raman spectroscopy offers significant advantages over standard incoherent Raman spectroscopy. The advantages include 105 improvement in conversion efficiency, spectral and spatial discrimination against fluorescence, low incident average power, and no requirement for a monochromator. The potential disadvantages of signal scaling as power cubed and requirement for a high peak power tunable laser source are largely overcome by presently available tunable laser sources. The method appears particularly useful for investigating biological compounds where background fluorescence is a problem for conventional spontaneous Raman studies. We show that for low concentrations, the density-squared signal dependence becomes linear due to coherent mixing with an intense solvent Raman mode or the third-order background signal.
Low-loss parallel-plate waveguide at 10.6 μm
Authors: Nishihara H. , Inoue T. , Koyama J.
Published: January 2004

A slightly curved parallel-plate waveguide made of metal or dielectric material is proposed for a low-loss and self-focusing optical guide for CO2 laser beams. The minimum-loss TE1 mode in a copper guide with a separation of 0.5 mm has a transmission loss as low as 0.02 dB/m, and the loss is 6 times less than that of the TE01 mode in the hollow circular guide of diameter equal to the separation. Theoretical prediction of the low-loss and self-focusing characteristics of the waveguide has been experimentally confirmed.
Anomalies in the surface plasmon resonance excitation at both surfaces of evaporated metal films
Authors: Weber Willes H. , McCarthy S. L.
Published: January 2004

Measurements of the resonant excitation of surface plasmons at both the air and substrate surfaces of evaporated Ag films indicate that the real part of εAg is a larger negative number at the substrate interface. This difference can be explained with a Maxwell-Garnett type theory which assumes that the film density near the air surface is several percent below that near the substrate interface.
Semiconductor-electrolyte interface devices for solar energy conversion
Authors: Jayadevaiah T. S.
Published: January 2004

A new application of the well known semiconductor-electrolyte interface is reported in this letter. The space-charge layer necessary for photovoltaic processes is simply created in the semiconductor-electrolyte interface by the charge transfer process. Application of this interface for solar energy conversion is quite interesting. These cells avoid the costly and elaborate p-n junction fabrication and allow the use of polycrystalline and amorphous semiconductors for photovoltaic conversion.
Tunable dye laser pulse converter for production of picosecond pulses
Authors: Chan C. K. , Sari S. O.
Published: January 2004

An open flowing Rh6G dye laser, cavity length tuned to a mode-locked Ar+ laser, has been used to generate continuous pulse trains tunable from 5600 to 6100 Å over the dye lasing bandwidth. Interferometric pulsewidth measurement using second harmonic generation yields a pulsewidth of 2.8 ps.
Nondestructive technique for the precise evaluation of optical waveguides
Authors: Kato Daisuke
Published: January 2004

In order to offer an effective method to measure a characteristic such as the light attenuation in an optical waveguide without breaking or contacting the sample, regular light scattering signals have been separated from the irregular ones by rejecting the Rayleigh component.
Streak camera investigation of the self-focusing onset in glass
Authors: Campillo A. J. , Fisher Robert A. , Hyer R. C. , Shapiro S. L.
Published: January 2004

The onset of self-focusing in a glass sample has been studied with a streak camera. After passing through the sample, the beam is no longer focused by a subsequent lens into a nearly diffraction-limited spot, but rather into a time-dependent ring. A simple model explains these results and indicates practical limitations for uniformly illuminating small targets with a Nd:glass laser chain.
Temperature dependence of the gold acceptor energy level in silicon
Authors: Engström O. , Grimmeiss H. G.
Published: January 2004

Using the spectral distribution of the optical emission rates it is shown that the gold acceptor energy level in silicon is probably pinned to the conduction band in the temperature range between 90 and 242 K.
Transport and localized levels in amorphous binary chalcogenides
Authors: Bube Richard H. , Mahan John E. , Shiah Ralph T.-S. , Plas Hubert A. Vander
Published: January 2004

Measurements of photoconductivity versus intensity and temperature, photoconductivity decay, thermoelectric power versus temperature, and field effect have been extended to several binary amorphous semiconductors: Sb2Te3, As2Te3, As2Se3, and Ge2Te7, to be compared with earlier measurements on As2SeTe2 and Ge3Se2Te4 and more complex multicomponent chalcogenides. Analogous behavior is found in all these materials: about 1019 cm−3 eV−1 localized recombination levels within about 0.1 eV of the gap edges; about 1019 cm−3 eV−1 localized levels near the equilibrium Fermi level; thermally activated mobility with activation energy of the order of 0.1–0.2 eV. Crystallization produces an increase in photoconductivity at 100°K by over a factor of 106.
Quantum detection of microwave acoustic pulses
Authors: Martin M. , Desmons J. Y.
Published: January 2004

The effect of longitudinal phonons on a very wide Dayem bridge involving amplitude voltage steps ΔV=hv/2e of the detected echoes has been measured. The mechanism seems to be related to the motion of the vortices created by the dc bias current.
A single flux quantum Josephson junction memory cell
Authors: Zappe H. H.
Published: January 2004

Operation of a DRO single flux quantum Josephson junction memory cell is described. Writing and sensing is performed with coincident currents. The device acts as its own sense detector, switching to the gap voltage if a flux quantum was stored. Dense arrays not requiring standby power are potentially feasible.
Experimental observation of the switching transients resulting from single flux quantum transitions in superconducting Josephson devices
Authors: Guéret P.
Published: January 2004

We have made what we believe is the first experimental observation of the switching transients resulting from single flux quantum transitions in superconducting devices. For that purpose, we used ``long'' Josephson junctions or interferometers which exhibit overlapping vortex modes. By applying a magnetic field to such devices, vortex-mode transitions are induced. The resulting transients are detected by a small Josephson junction located nearby. The experimental results show unambiguously that the points where a signal is detected by the sense junction correspond to the vortex-mode boundaries of the device. These results have important implications for memory applications.
Quantitative assessment of laser-induced stress waves generated at confined surfaces
Authors: Fairand B. P. , Clauer A. H. , Jung R. G. , Wilcox B. A.
Published: January 2004

Laser-induced stress waves in iron samples were analyzed by measuring the pressure environment at the back surface of various sample thicknesses. These results were compared with numerical calculations obtained from a one-dimensional radiation hydrodynamics computer code. The experiments were conducted in an air environment under ambient conditions and the metal surfaces were confined by transparent overlays. Peak pressures exceeding 50 kbar were measured with quartz pressure transducers at a laser power density of about 109 W/cm2. Computer predictions agreed favorably with the experimental results and indicated that peak pressures exceeding 100 kbar could be generated by appropriate modifications in the laser environment and target overlay configuration.