bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of OH in the atmosphere using a dye laser
Authors: Baardsen E.L. , Terhune R.W.
Published: January 2004

Preliminary experiments suggesting the feasibility of using a resonance fluorescence scheme to detect ambient concentrations of OH in the atmosphere (106 molecules/cm3) were carried out using OH concentrations near 1012 molecules/cm3. The P1(1) line of the v = 0 → 1 branch of the lowest electronic transition of OH at 2822 Å was resonantly excited with radiation from a doubled dye laser. The subsequent fluorescence from the v = 0 → 0 branch with Δν ≅ 3050 cm−1 was observed to have a fluorescence efficiency of 0.6 × 10−3 in N2 at atmospheric pressure with a 10-mm partial pressure of H2O. This fluorescence occurs 500 cm−1 away from any strong Raman line in the atmosphere.
Electro-optical activity of crystals
Authors: Anastassakis E.
Published: January 2004

It is shown that the well-known piezomagnetic tensor can be used to determine those experimental configurations in which the electro-optical activity can be separated from birefringence, optical activity, and linear electro-optical effect.
Attenuation of multimode glass optical waveguides
Authors: Keck D.B. , Schultz P.C. , Zimar F.
Published: January 2004

Glass optical waveguides show great promise of being the transmission medium for optical communication links. Single-mode waveguides have already been reported having a total attenuation of less than 20 dB/km. In this work we report measurements on the first low-loss multimode glass waveguide. These measurements include both total attenuation as a function of wavelength and total radiation attenuation at 632.8 nm. Total attenuation as low as 7 dB/km was observed near 1060 nm. This is due in part to fabrication techniques which diminished the OH concentration in the glass. A total radiation loss of 12.3 dB/km was measured that is higher than that predicted solely by Rayleigh scattering.
Pyroelectric effect in Tl3AsSe3
Authors: Deis D.W. , Roland G.W.
Published: January 2004

The room-temperature pyroelectric coefficient of Tl3AsSe3, a hexagonal nonferroelectric crystal, is 0.35 μC/cm2 °K, one of the largest observed to date. This large pyroelectric coefficient and the measured electrical properties make this material attractive for pyroelectric detector applications.
Mechano-optic polarization modulator using a reflection diffraction grating
Authors: Azzam R.M.A. , Bashara N.M.
Published: January 2004

A mechano-optic polarization modulator is described which uses a diffraction grating from which incident s-polarized (perpendicular to the plane of incidence) light is obliquely reflected. Rotation of the grating around its normal causes optical rotation of the plane of polarization of the reflected light. The ellipticity and amplitude modulation which accompany this azimuth modulation are insignificant. The modulation is linear up to a limit determined by the onset of a surface-plasmon-excitation anomaly. A 610-lines/mm diffraction grating is used to linearly modulate a 6328-Å He–Ne laser with a modulation index of 0.183° of optical rotation per degree of mechanical rotation. This modulation effect is useful in instruments that use polarization-modulated light and ac phase detection. It also provides a method for optical measurement of torsional oscillations.
Current-voltage characteristics of Al–SiO2–Si structures
Authors: Av-Ron M. , Shatzkes M.
Published: January 2004

Experimental results are presented on conduction, breakdown, and switching in Al–SiO2–Si MOS dots. Transitions from the low-conduction state are found to terminate in self-healing breakdowns. There also exists a higher-conduction state in which destructive breakdowns do not occur.
Tests on superconducting helix resonators
Authors: Benaroya R. , Jaffey A.H. , Johnson K. , Khoe T. , Livingood J.J. , Nixon J.M. , Parker G.W. , Ramler W.J. , Aron J. , Wesolowski W.A.
Published: January 2004

A niobium helix-resonator cavity close to the frequency suitable for a heavy-ion accelerator has been subject to an 8-week test, including 323 h at full power (axial electric field Eax>2.5 MV/m). The cavity, with an anodically deposited protective film of Nb2O5, had a high Q and supported high fields without deterioration over the whole period during which it was subject to a moderate internally generated x-ray dose. Properties were found to be stable against considerable thermal cycling and exposure to air. Measurement of emitted x-ray maximum energy allowed an independent corroboration of the field measurement calibration.
Comparison of the oxidation process in strontium and cerium by ultraviolet photoelectron spectroscopy
Authors: Helms C.R. , Spicer W.E.
Published: January 2004

The ultraviolet photoemission technique has been applied to the study of the oxidation of strontium and cerium. It has been found that the photoemission measurement provides a method to determine the oxide growth rate perpendicular to the surface, the composition of the surface, and the stable oxide phases formed during the oxidation process.
Generation of infrared radiation in a metal-to-metal point-contact diode at synthesized frequencies of incident fields: a high-speed broad-band light modulator
Authors: Sanchez A. , Singh S.K. , Javan A.
Published: January 2004

This letter reports for the first time the detection of infrared radiation emitted from a metal-to-metal point-contact diode as the result of mixing the frequencies of the radiation fields applied to the diode.
Secondary electron emission from GaAs
Authors: Gutierrez W.A. , Pommerrenig H.D. , Holt S.L.
Published: January 2004

Secondary emission measurements have been made on thick and thin epitaxially grown p-doped GaAs. Reflection mode gains of 400 at primary voltages of 20 kV have been observed for unthinned layers. The variation of gain with white-light photoresponse has also been measured. For 5-μ-thick self-supporting layers, a gain of 115 and 30 (at 10 kV primary voltage) has been measured for the reflection and transmission modes, respectively. The escape depth is estimated to be 2 μ with an escape probability of 0.14.
Interaction of laser light with magnetic domains
Authors: Ashkin A. , Dziedzic J.M.
Published: January 2004

Laser beams, when partially absorbed in epitaxial (Er2Eu1Ga0.7Fe4.3O12) magnetic garnet films, are used to thermally manipulate bubble and strip magnetic domains. Bubbles and strips can be created or annihilated, as well as captured and moved about freely by the light spot, without the use of magnetic circuits. Bubbles can be arranged in fixed arrays or propagated at high speeds. A novel form of reversible strip domain writing is demonstrated.
Efficiency shift in very high efficiency GaP (Zn–O) diodes
Authors: Solomon R. , DeFevere D.
Published: January 2004

High-efficiency GaP (Zn–O) diodes have been observed, in some instances, to show a substantial and permanent increase in efficiency when subjected to a large forward bias. Experiments suggest that the effect is related to precipitation in the n and p layers. A model is presented which is able to account for most of the observations.
Magnetostatic potential wells and drive fields in field access bubble domain drive circuits
Authors: George P.K. , Chen T.T.
Published: January 2004

A technique for experimentally measuring the z-component fields produced by Permalloy drive circuits in the presence of both bubble and external in-plane drive fields is proposed. Experimental results based upon this technique are presented for a simple bar, a Y-bar propagation pattern and a chevron propagation pattern. The implications of these results with respect to device operation and design are discussed.
Single-frequency traveling-wave Nd:YAG laser
Authors: Clobes A.R. , Brienza M.J.
Published: January 2004

Single-frequency operation of a cw pumped Nd:YAG laser was achieved by using a ring cavity configuration containing a small differential loss. The resulting unidirectional traveling wave eliminated spatial hole burning, and the output of the laser was at a single frequency.
R-branch emission from a cw CO chemical laser
Authors: Jeffers W.Q.
Published: January 2004

The effect of adding vibrationally ``cold'' CO to a CO chemical laser is shown to increase the inversion ratios on the vibration levels of the chemically formed molecules. This fact is demonstrated experimentally by the observation of R-branch emission, reported here for the first time in any cw flow and mixing chemical laser. R-branch lines can be seen experimentally only with the addition of cold CO, and then only with a frequency-selective optical cavity. Theoretical calculations indicate that the total inversions predicted from the known distribution of the O + CS pumping reaction are rapidly depleted by vibration-vibration (VV) relaxation. The collisional VV exchanges with cold CO are shown to increase the vibrational inversion ratios to the extent that total inversion is observable in experimental devices limited by mixing and reaction times that are not fast compared with VV equilibration.
Secondary hydrodynamic structure in dynamic scattering
Authors: Sussman Alan
Published: January 2004

A hydrodynamic regime in dynamic scattering has been observed in which the relaxation time depends on the voltage at turnoff. This regime manifests itself, above a threshold voltage, with microscopic regions of increased on-axis optical density which grow until the whole cell area is converted. It has been found in all nematic materials which exhibit dynamic scattering. With originally perpendicular homeotropic orientation, the speed of relaxation increases with the square of the voltage at turnoff. With originally parallel homeotropic orientation, the speed of relaxation decreases with increasing voltage at turnoff. The time t to fill a given area depends on the current density and the voltage above a second threshold Vm, according to the empirical relation J(V - Vm)t = const. For MBBA, the second threshold is about 15 V, and the constant 10−3 J/cm2. The relation is independent of current density, temperature, and thickness (greater than 10−4 cm). This phenomenon may explain variations in response as seen by different workers. A hydrodynamic model is proposed, with contributions attributable to the dielectric anisotropy.
Auger spectroscopic observation of Si–Au mixed-phase formation at low temperatures
Authors: Narusawa T. , Komiya S. , Hiraki A.
Published: January 2004

When a Si crystal substrate is covered with evaporated Au and heated at relatively low temperatures (100–300 °C) in an oxidizing atmosphere, because of the Si–Au reaction at the interface, a SiO2 layer is readily formed over the Au layer. Present Auger spectroscopic study concludes that the reaction induces a Si–Au mixed phase that is almost identical with the Si–Au alloyed phase obtained by heat treatment in a high vacuum at temperatures well above the Si–Au eutectic point (370 °C). The Auger spectra of Si in both the mixed and alloyed phases differ obviously from that of the pure Si crystal.
Efficient pulsed chemical laser
Authors: Suchard S.N. , Ching A. , Whittier J.S.
Published: January 2004

Output pulse observations are presented for a helium-diluted CO2 laser pumped by VV (vibration-vibration) energy transfer from vibrationally excited DF produced by the D2–F2 chain reaction. Flash photolysis of the F2 served to initiate the reaction. A 290-cm3 reaction chamber containing a 0.5-atm mixture with mole ratio D2:F2:CO2:He = 0.33:1:8:10 gave a single-pulse output energy of 2.8 J. Relative to the amount of D2 present in the reaction chamber, this corresponds to a chemical efficiency greater than 5%.
Self-mode-locking of a transversely excited N2 laser in the first positive system at 1.048 μm
Authors: Gleason T.J. , Willett C.S. , Curnutt R.M. , Kruger J.S.
Published: January 2004

An investigation has been made of the spontaneous self-mode-locking in a transient transversely excited N2 laser operating in the first positive system (B3πg−A 3Σu+) in molecular nitrogen on the 0–0 band at 1.048 μm. The laser emission, which had a typical pulse length of 60 nsec, consisted of a train of mode-locked pulses of about 6-nsec duration with a peak power of about 0.5 kW.
Effect of thick Cs–O layers on photoemission from negative-electron-affinity cathodes
Authors: Sonnenberg H.
Published: January 2004

The effect of thick Cs–O layers on photoemission from GaAs and InAs0.4P0.6 cathodes is experimentally investigated. Simple empirical relationships between the yield and thickness and between the escape probability and thickness are given.
Use of rotated electrodes for amplitude weighting in interdigital surface-wave transducers
Authors: van den Heuvel A.P.
Published: January 2004

Amplitude weighting in an interdigital surface-wave transducer array may be achieved by misaligning the electrodes with the incident-wave phase fronts. Since in this method all the electrodes are full aperture, the problems of diffraction loss and phase-front distortion are avoided. Transducers employing this method of weighting to achieve a flat bandpass response were used to construct delay lines on quartz and lithium niobate, and their performance is shown to be in reasonable agreement with predictions.
Experimental investigation of electron emission of a tungsten cathode in a cesium plasma
Authors: Blom J.H. , Pels H.J.
Published: January 2004

The voltage drop at a tungsten cathode surrounded by cesium plasma is measured as a function of the current density and temperature of the cathode. Current densities, an order of magnitude higher than predicted by the Langmuir S curves, accompanied with low voltage drops, have been measured for certain cathode temperature regimes. These results seem to be of interest for the emission properties of electrodes in closed-cycle MHD generators.
High-speed Pb1−xSnx Te photodiodes
Authors: Andrews A.M. , Higgins J.A. , Longo J.T. , Gertner E.R. , Pasko J.G.
Published: January 2004

Low-capacitance (< 10 pF) Pb1−xSnxTe photodiodes operating near 77 °K (areas 1.7 × 10−4 cm2) have been obtained via liquid-phase epitaxial growth of low-carrier-concentration material (low 1014 cm−3 to high 1015 cm−3). Response to a mode-locked 1.06-μm Nd:YAG laser with the devices terminated in 50 Ω indicated a frequency response to 400 MHz. With a 14-Ω load and by exciting a photocurrent with radiation from a CO2 laser, the shot noise rolloff point was found to be 1200 MHz. Optimum parameters have not yet been achieved, as evidenced by the increase in frequency response with increase in reverse bias; these results represent only a lower limit to this material's capability.
Double-heterostructure GaAs : Si diode lasers
Authors: Rossi J.A. , Hsieh J.J.
Published: January 2004

Double-heterostructure diode lasers with Si-doped active regions have exhibited laser action within the wavelength range 9100–9500 Å under pulsed room-temperature conditions. Threshold current densities are typically 4 × 103−1.1 × 104 A/cm2, and total power conversion efficiencies are ∼ 1–3%.
Highly anisotropic columnar structures in silicon
Authors: Levinson Lionel M.
Published: January 2004

Unidirectional solidification of the CrSi2–Si eutectic leads to formation of an oriented array of CrSi2 fibers embedded in a matrix of Si. The aligned eutectic is highly anisotropic, with resistivity parallel and perpendicular to the CrSi2 fiber alignment axis characterized by ρ⊥/ρ∥≈ 103−104 for a specimen produced from 100-Ω cm Si and 99.996% iodide chromium.
Fundamental transverse electric field (TE0) mode selection for thin-film asymmetric light guides
Authors: Suematsu Yasuharu , Hakuta Mitsuari , Furuya Kazuhito , Chiba Kazuhiro , Hasumi Ritsuo
Published: January 2004

TE0 mode selection was observed in an asymmetric dielectric light guide with a metal-film outer coating. TM0 mode and higher-order modes could not transmit through the guide, whereas the loss of the TE mode, the insertion loss, was small. The experimental data were in good agreement with the theoretical results given here. Filter action is explained by modal repulsion from the metal wall that is inherent in an asymmetric guide.
Evanescent-field-pumped dye laser
Authors: Ippen E.P. , Shank C.V.
Published: January 2004

A new dye laser pumping scheme is described in which molecules lying external to a waveguiding film are excited via evanescent fields from an optical pump contained in a waveguide. The excited molecules lying close to the surface then emit into a waveguide mode. An experiment is performed in which Rhodamine 6G in benzyl-alcohol glycerol mixtures is excited by an optical evanescent field contained in a waveguiding film.
Densities of amorphous Si films by nuclear backscattering
Authors: Brodsky M.H. , Kaplan D. , Ziegler J.F.
Published: January 2004

The backscattering of 2500-keV alpha particles is used to measure the densities of amorphous Si films. The density of amorphous Si is found to be inversely proportional to the electron spin resonance signals. The extrapolated density at zero spins is equal to 1.01 ± 0.02 times that of crystalline Si. The highest density achieved in a real amorphous film was 0.97 ± 0.02 times the crystalline density.
Thin birefringent polymer films for integrated optics
Authors: Sosnowski T.P. , Weber H.P.
Published: January 2004

The fabrication of low-loss (0.1 dB/cm) thin birefringent polymer films on glass substrates is reported. A birefringence of 4.7 × 10−3 was measured in polystyrene. In such films, TE and TM modes can be made degenerate by controlling the film thickness. Degeneracy over distances of up to 3 cm was achieved. Such guides may simplify the construction of modulators and other devices requiring degenerate mode operation.
Optical damage in KTN
Authors: King S.R. , Hartwick T.S. , Chase A.B.
Published: January 2004

An analysis of light-induced refractive-index changes (``optical damage'') has been carried out for paraelectric electro-optic crystals. The results are compared with experimental data taken on several KTN crystals. Both the spatial extent and temporal variations of optical damage are accurately determined by the theory for all crystals tested. The rate at which optical damage occurs can be used to determine the product of absorption, mobility, and lifetime for the material.
High-performance photon drag detector for a CO2 laser using p-type tellurium
Authors: Panyakeow S. , Shirafuji J. , Inuishi Y.
Published: January 2004

A photon drag detector with high sensitivity at 10.6-μ radiation from a Q-switched CO2 laser was developed by using p-type tellurium. The observed value of the photon drag signal at 77 K was as high as 5 mV on a 5-mm-long sample, perpendicular to the c axis, when the peak intensity of the incident laser pulse was 1 kW. The photon drag effect is dominantly generated by light holes, so that the polarity of the induced voltage is consistent with that expected on the basis of momentum transfer from photons to holes. There was observed no polarity change over a temperature range in the present experiment, in contrast to p-type germanium. The momentum relaxation time in the light hole band was estimated to be about 10−14 sec.
Cs–O negative-electron-affinity surfaces on silicon
Authors: Howorth J.R. , Holtom R. , Harmer A.L. , Trawny E.W.
Published: January 2004

The thickness of cesium and oxygen deposits required to produce negative electron affinity on semiconductors is not clear from published data. Photoemission measurements show that, for heavily doped p-type silicon, negative electron affinity can be achieved with either monolayer or thick deposits of cesium and oxygen, whereas deposits of intermediate thickness are less effective. The results also show that for silicon the lowest effective work function can be achieved by monolayer activation.
Quenching of laser dye fluorescence by absorption from an excited singlet state
Authors: Wieder Irwin
Published: January 2004

Quenching of fluorescence of common laser dyes is observed and measured as a function of the intensity of an excitation pulse at 3371 Å and the concentration of the dye. The observed effects can be explained by a model where there are sequential absorptions of pump radiation from the ground state and first excited singlet state followed by a radiationless decay, and where molecules can be cycled many times during each excitation pulse.
Optical waveguides by diffusion in II-VI compounds
Authors: Martin W.E. , Hall D.B.
Published: January 2004

Planar optical waveguides have been made by sealed ampoule diffusion of Cd and Se into ZnS and Cd into ZnSe. Three-dimensional diffused guides of Cd-diffused ZnSe have been made by using a masking layer of evaporated oxidized SiO, which was shadowed with silica or glass fibers or copper wire. Structures 50 and 160 μm wide and 10 μm deep with severely etched surfaces yielded losses of 10 dB/cm. Suppression of thermal etching in small-index-gradient guides 10 μm wide by 3 μm deep gave losses of less than 3 dB/cm.
Direct determination of Hall mobility of photoelectrons in the ferromagnetic semiconductor EuO
Authors: Kajita Koji , Masumi Taizo
Published: January 2004

The importance of applying the pulsed Redfield technique in the direct determination of the Hall mobility μH of photocarriers in ferromagnetic semiconductors is exemplified, for the first time, by using pure EuO crystals. The value of μH is obtained directly from the measurement of the Hall angle θ = μHB/c, where B is the magnetic induction and c is the light velocity. Thus, it is shown that a large negative-magnetoresistance effect in undoped EuO crystals near the Curie temperature Tc can be attributed mainly to the mobility change. The photocarriers are identified to be electrons, and a mobility value as high as 250 cm2/V sec is observed at 26 °K.
Energy losses of hot electrons in a thin layer of SiO2 on Si
Authors: Poirier R. , Olivier J.
Published: January 2004

In vacuo photoemission from SiO2-covered Si shows that the quantum yield and the energy threshold depend on the SiO2 layer in the 10- to 120-Å thickness range. These effects have been explained by electron-optical phonon scattering in the thin SiO2 layer before one Si-emitted electron escapes into the vacuum. An approximate value of the phonon energy at the center of the Brillouin zone (ΔE = 83 meV) and a mean free path for phonon scattering (l = 35 Å) are given.
Simultaneous two-wavelength selection in the N2 laser-pumped dye laser
Authors: Pilloff Herschel S.
Published: January 2004

A technique is reported which allows simultaneous two-wavelength selection in the N2 laser-pumped dye laser. The two wavelengths are continuously tunable anywhere within the optical gain region of the particular dye solution used, and the two output beams are collinear and collimated, have mutually orthogonal polarizations, and in general can be temporally synchronized. Following the description of this device, the extension of this technique to other lasers and a few potential applications will be briefly discussed.
CO TEA laser at 77°K
Authors: Cohn D.B.
Published: January 2004

A CO TEA laser, cooled to 77°K by a surrounding liquid-nitrogen bath, is found to exhibit laser action on approximately 60 transitions over the spectral range 4.960–5.610 μm. Following a single 0.5-μsec excitation pulse, lasing action is observed to continue up to 2 msec with 15 Torr of CO and up to 4 msec with a 14-Torr CO–N2 mixture.
Absorption saturation in germanium, silicon, and gallium arsenide at 10.6 μm
Authors: Gibson A.F. , Rosito C.A. , Raffo C.A. , Kimmitt M.F.
Published: January 2004

The absorption of p-type Ge, Si, and GaAs at 10.6 μm decreases at high intensities. The saturation intensity of Ge, 10 MW cm−2, is sufficiently low for it to be used for passive mode locking of a TEA laser.
Low-loss epitaxial ZnO optical waveguides
Authors: Hammer J.M. , Channin D.J. , Duffy M.T. , Wittke J.P
Published: January 2004

Optical waveguide losses below 5 dB/cm have been measured on single-crystal epitaxial ZnO films grown on Al2O3. These films promise to be useful in a variety of active integrated optic applications. Comparison of the details of loss measurements with carrier density and mobility measurements gives information on possible loss mechanisms.
Importance of Fresnel reflections in laser surface damage of transparent dielectrics
Authors: Crisp M.D. , Boling N.L. , Dubé G.
Published: January 2004

It is shown that interference between incident and reflected light waves at the surfaces of a transparent dielectric material significantly influences surface damage thresholds. For normal incidence the light that is reflected at the entrance face of a surface is 180° out of phase with the incident light, and the resulting interference causes a sizable reduction in the electric field at the entrance face. The light reflected at the exit face suffers no phase shift, and as a result its interference with the incident light slightly increases the electric fields experienced at the exit surface. The analysis predicts a definite ratio for the damage threshold of the entrance and exit surfaces. This and one other prediction are experimentally investigated for Owens-Illinois ED-2 laser glass.
Wall mobility and velocity saturation in bubble-domain materials
Authors: Callen H. , Josephs R.M. , Seitchik J.A. , Stein B.F.
Published: January 2004

The conventional dynamical equations of wall motion are modified by a phenomenological nonlinear damping factor to describe the nonlinearity and velocity saturation observed in some bubble materials. We show that under certain restrictive but common conditions the solution of the resultant nonlinear differential equation can be obtained from the conventional linear solution by the simple transformation t → t ± x/v, where v is the saturation velocity. The conditions for this solution are (a) that the inertial terms are negligible and (b) that the motion is such that the velocity does not change sign. Solutions of the modified dynamical equation are compared with measurements of step-function wall response and of bubble collapse in Y2.4Eu0.6Fe3.8Ga1.2O12, and it is shown that the measurements are consistently and adequately described by the nonlinear dynamical equation. The nonlinear damping also modifies the equation describing bubble velocity in gradient fields, and it is shown that the modified equation is consistent with propagation data.
Ageing of the residual surface resistance of superconducting lead cavities
Authors: Danielsen M.
Published: January 2004

Measurements of the residual surface resistance of superconducting lead cavities as a function of time during a period of a month showed an oscillating variation. An explanation of the ageing curves is proposed.
High-efficiency Ga1−xAlxAs–GaAs solar cells
Authors: Woodall J.M. , Hovel H.J.
Published: January 2004

Heterojunction solar cells consisting of pGa1−xAlxAs–pGaAs–n GaAs are grown by liquid-phase epitaxy and exhibit power conversion efficiencies of over 16% (corrected for contact area) measured in sunlight for air mass 1 at sea level, while efficiencies of 19–20% are obtained for an air mass value of 2 or more. The improved efficiencies compared to conventional homojunction (Si and GaAs) cells are attributed to the reduction of series resistance and the reduction of surface recombination losses resulting from the presence of the heavily doped Ga1−xAlxAs layer. Open-circuit voltages of 0.98–1.0 V and short-circuit currents of 18–21 mA/cm2 (corrected for contact area) are observed for a solar input intensity of 98.3 mW/cm2.
Photosensitive field emission from silicon point arrays
Authors: Thomas R.N. , Nathanson H.C.
Published: January 2004

Efficient photoemission has been demonstrated from uniform large-area arrays of field emitters, fabricated at densities of 106 in.−2 by microetching techniques in p-type silicon. Such arrays were shown to emit electrons into vacuum when biased by a closely spaced plane anode (125- to 500-μm spacing) at a few kilovolts. No high-vacuum cesiation or high-temperature cleaning is required to observe this emission. Stable reflective photosensitivities exceeding 1500 μA/lm and quantum efficiencies of 2% at 1.06 μm and 28% at 0.90 μm have been demonstrated in thick p-type silicon arrays.
Transmissive-mode silicon field emission array photoemitter
Authors: Thomas R.N. , Nathanson H.C.
Published: January 2004

The photosensitivity of thin silicon field-emitter array structures has been investigated in transmission over the 0.4- to 1.1-μm spectral region. Quantum yields of 45% at 0.90 μm and 0.5% at 1.06 μm have been measured at 90 °K. Image formation at wavelengths longer than 0.85 μm with a resolution approaching 10 line pairs/mm has been demonstrated with prototype 30-mm-diam target structures. It is also shown that large-area avalanche multiplication of carriers may be used without significant image degradation.
Switching and modulation of light in magneto-optic waveguides of garnet films
Authors: Tien P.K. , Martin R.J. , Wolfe R. , Le Craw R.C. , Blank S.L.
Published: January 2004

We report for the first time switching and modulation of light in a magneto-optic waveguide that is a single-crystal epitaxially grown iron-garnet film. These experiments involve the Faraday rotation of the magnetic film and the motion of magnetization in the plane of the film. We have modulated light from a 1.152-μm laser up to 80 MHz. We were also able to switch light between two waveguide modes by applying a magnetic field as small as 0.2 Oe.
Microwave Kerr effect on polar liquids
Authors: Najim M. , Matheau J.C. , Lefeuvre S.
Published: January 2004

It is possible under some restrictive conditions on the choice of dielectric materials to show and measure Kerr effect at microwave frequencies. The quadratic Kerr law is verified and the Kerr constant is calculated in the X-band for tri-o-cresylphosphate and cyclohexanol.
Noncollinearly phase-matched second-harmonic generation in LilO3
Authors: Umegaki Shinsuke , Yabumoto Seiichi , Tanaka Shun-ichi
Published: January 2004

Efficient second-harmonic generation of light, where the wave-vector-matching condition is satisfied noncollinearly or two-dimensionally, has been observed using a Nd:YAG laser as a fundamental and LiIO3 as a nonlinear crystal. The phase-matching condition has been found to be satisfied in a wide range of the angle around the optic axis of the crystal.
Schottky barrier height dependence on Si crystal orientation
Authors: Gutknecht P. , Strutt M.J.O.
Published: January 2004

Planar Al–nSi and PtSi–nSi Schottky barriers with diffused p-type guard rings have been fabricated on (111) and (100) silicon surfaces. The barriers have been produced by sputtering the metals on sputter-etched silicon surfaces. For Al–nSi barriers the barrier height is 0.72 eV on (111) surfaces and 0.81 eV on (100) surfaces, as determined from the forward I-V characteristic. This difference in barrier potential has been confirmed by C-V measurements. No difference in barrier height is found for PtSi–nSi barriers made on (111) and (100) surfaces. A qualitative explanation is given for the experimental results in terms of strong or weak coupling of surface states to the metal.
Amplification at 1.06 μm using a Nd : glass thin-film waveguide
Authors: Yajima Hiroyoshi , Kawase Shigeki , Sekimoto Yasuo
Published: January 2004

Nd-doped glass (3.5 wt% Nd2O3) is sputtered on Corning No. 7059 glass to make an active thin-film waveguide. The thin film is pumped with a Xe flash tube, and the amplification of 1.06-μm laser light that propagates in the thin film is observed.
Electron energy relaxation times in GaAs and InP
Authors: Glover G.H.
Published: January 2004

The field-dependent energy relaxation times of electrons in GaAs and InP have been determined from the 34-GHz complex conductivity measured in the presence of a dc heating field. The values for GaAs and InP are 2.5 and 1.7 psec, respectively, at low fields, but increase rapidly near the bulk-effect threshold field values. Moreover, the relaxation time for InP is found to be less than that for GaAs at all fields. These results are in qualitative accord with predictions based on velocity-field measurements.
Photoinitiated and photosustained laser
Authors: Seguin H. , Tulip J.
Published: January 2004

The gases and cathode of a TEA CO2 laser are irradiated with uv radiation. The resulting photoionization and photoemission initiate and assist in sustaining a high-energy low-field-strength discharge. Output energy of 50 J/liter at an efficiency of 15% has been obtained in an initial demonstration.
Coincidence of Er : YAG laser emission with methane absorption at 1645.1 nm
Authors: White Kenneth O. , Schleusener Stuart A.
Published: January 2004

A recently developed solid-state-laser-simulated tuning technique has been used to investigate the coincidence of Er : YAG laser emission with methane (CH4) gas absorption in the 1.6-μm region. When the laser is operated under maximum-bandwidth conditions, full coincidence is obtained, thus enabling possible remote sensing of CH4 in the eye-safe region. Unresolved fine structure of the CH4 absorption line was indicated.
Nonlinear loss in Nd-doped laser glass
Authors: Penzkofer A. , Kaiser W.
Published: January 2004

The amplifier gain and the energy transmission in Nd-glass were investigated as functions of light intensity using single picosecond pulses. The observed reductions of gain and transmission are well accounted for by a two-photon absorption process in the Nd3+ system. There is good agreement between the measured and calculated two-photon absorption cross section of σ′ = (1.3 ± 0.3) × 10−32 cm4/W. The two-photon absorption limits the obtainable output intensity in a Nd-glass amplifier and reduces the self-focusing action in the material.
Instantaneous velocity correlations from a single dopplermeter
Authors: MacIntyre Ferren
Published: January 2004

A new method for measuring velocities and velocity structure functions of turbulence with a single dopplermeter (laser Doppler-shift velocimeter) is analyzed by optical mixing theory. The zero-mean-velocity signal is mixed electronically with a local oscillator before FM demodulation to recover the instantaneous velocity.
Electrical CO-mixing gas-dynamic laser
Authors: Brunet H. , Mabru M.
Published: January 2004

An electric-discharge CO-mixing laser is described in which N2 is vibrationally excited in an electrical discharge and then mixed with cold CO in a supersonic expansion providing a population inversion between CO vibrational bands. Continuous output is achieved from an optical cavity established transverse to the flow. Maximum laser power obtained to date is 45 W, corresponding to an efficiency of 4% and a volumetric power density of 6 W/cm3.
Identification of donor species in high-purity GaAs using optically pumped submillimeter lasers
Authors: Fetterman H.R. , Waldman J. , Wolfe C.M. , Stillman G.E. , Parker C.D.
Published: January 2004

An optically pumped NH3 laser has been used in conjunction with careful doping experiments in high-purity GaAs to determine the ionization energy of isolated tin donors. The energy obtained is 5.820 meV, which corresponds to a central-cell correction of 0.081 meV. This technique for impurity analysis is estimated to be sensitive to donor concentrations of less than 1011 cm−3.
Mass motion as observed by light-beating spectroscopy
Authors: Ben-Yosef N. , Zweigenbaum S. , Weitz A.
Published: January 2004

In the power spectra of the scattered light from silver chloride colloidal particles in water, a Lorentzian shifted from zero frequency has been observed in addition to the zero-centered one. The shifted peak is attributed to the mass motion due to liquid flow resulting from the heating of the illuminated part by the laser beam.
Isotope-shift Zeeman effect for trace-element detection: an application of atomic physics to environmental problems
Authors: Hadeishi Tetsuo
Published: January 2004

Bitter's magnetic scanning method was applied to the detection of trace amounts of mercury, using the Zeeman effect of an isotope-shifted 198Hg line. This new technique for trace-element detection makes it possible to detect Hg in the ppb (part-per-billion) range directly from a host material in a few seconds.
Surface charge effects on the resistivity and Hall coefficient of thin silicon-on-sapphire films
Authors: Ham W.E.
Published: January 2004

Surface depletion due to surface charges was observed on thin films of silicon on sapphire spinel. A gated metal-oxide-semiconductor (MOS) Hall bar structure with a deposited silicon dioxide dielectric was used to determine the true average properties of the films. It is shown that these charges can cause very serious errors in the interpretation of resistivity, Hall coefficient, and mobility data. A decreasing mobility into the films is directly observed.
Effect of channeling and irradiation temperature on the morphology of blisters in niobium
Authors: Kaminsky M. , Das S.K.
Published: January 2004

The morphology of blisters formed in monocrystalline and polycrystalline niobium samples under 0.5-MeV 4He-ion impact at 900°C has been studied. For the irradiated monocrystalline samples, the results reveal that the shape and size of the observed blisters are highly dependent on channeling conditions.
High magnetic coercivity of neodymium- and didymium-cobalt alloys sintered with Pr and Sm additives
Authors: Tsui J.B.Y. , Strnat K.J. , Schweizer J.
Published: January 2004

The coercive forces of micron-sized NdCo5 and DiCo5 are less than 200 Oe. When these compounds were sintered with Pr–Co and Sm–Co as sintering aids, relatively high coercivities could be obtained. The highest coercivities of sintered NdCo5 and DiCo5 are 4000 and 10 280 Oe, respectively.
The effect of inhomogeneities in acoustic-surface-wave amplification
Authors: Burke B.E. , Bers Abraham
Published: January 2004

We present the results of a theoretical analysis of acoustic-surface-wave amplification by a sheet of electrons whose density and drift velocity vary along the common direction of acoustic wave propagation and electron drift. Such inhomogeneities not only may result from doping variations but are inherent for drifting electrons at the surface of a semiconductor because of fringing electric fields due to the applied dc potential. We propose the results as a possible explanation of the observed inability of such amplifiers to reach the maximum gain predicted by the homogeneous amplifier theory.
Effects of electropolishing on the tunneling current in aluminum-aluminum-oxide-aluminum diodes
Authors: Antula Jovan
Published: January 2004

The electropolishing of Al–Al2O3–Al structures using low-frequency (50 Hz) alternating current has been experimentally investigated. It is found that, by polishing, the tunnel film thickness could be increased up to 40% without changing the electrical capacitance of the film.
Internal photoemission: CdS-PVK and CdSe-PVK
Authors: Salaneck William R.
Published: January 2004

The electric field and temperature dependence of the quantum gain associated with the internal photoemission of holes from CdS and CdSe into poly(N-vinyl carbazole), i.e., PVK, are discussed in terms of a simple model of energy-loss scattering by holes near the PVK surface. Excellent qualitative agreement is obtained between simple analytical expressions derived on the model and data on CdS-PVK and CdSe-PVK.
Unstable resonators for CO2 electric-discharge convection lasers
Authors: Wisner George R. , Foster Martin C. , Blaszuk Paul R.
Published: January 2004

A series of unstable resonators have been operated in a convective CO2 electric-discharge laser, and the diffraction spreading angle of the output beams has been experimentally determined. Cavities with Fresnel numbers from 5.0 to 35 have been operated, and several of the resonators have produced essentially diffraction-limited output at power levels up to 1500 W.
Accumulation- and inversion-layer Hall mobilities in silicon films on sapphire
Authors: Ipri A.C.
Published: January 2004

The temperature dependence of electron and Hall mobilities in accumulation and inversion layers is presented for silicon-on-sapphire films. The inversion-layer mobilities, as a function of surface carrier density, are also given. It is suggested that the reduced mobility resulting in these layers is due to silicon-oxygen complexes located near the film surface. From the data presented, it is expected that deep-depletion n-channel transistors will have approximately 40% higher effective mobilities than conventional inversion-mode n-channel devices on sapphire.
Ohmic contacts on n+- and p+-Si by ion implantation
Authors: Feuerstein A. , Kalbitzer S.
Published: January 2004

Thin layers of n+- and p+-Si have been metallized by implantation of ion doses of 1017 Al/cm2 at energies of 8 keV. Ohmic characteristics have been obtained after moderate annealing treatments.
Charge storage in ZnIn2S4 single crystals
Authors: Romeo N. , Dallaturca A. , Braglia R. , Sberveglieri G.
Published: January 2004

We observe that, when ZnIn2S4 monocrystals at a temperature below 170°K are illuminated by light of the gap energy, the dark resistance, after illumination, is lowered by about nine orders of magnitude. This high-conductivity state persists until the crystals are either (a) warmed to room temperature, (b) exposed to light of a definite energy less than the gap width, or (c) placed in an electric field. We propose a level 1.76 eV above the valence band, with a repulsive barrier of 0.11 eV, which an electron must penetrate to enter this level and recombine.
Electro-optic contrast observations in single-domain epitaxial films of bismuth titanate
Authors: Wu S.Y. , Takei W.J. , Francombe M.H.
Published: January 2004

Electro-optic switching has successfully been demonstrated on untwinned (010) epitaxial bismuth titanate films grown on (110) MgAl2O4 substrates. This result is achieved on large-area films using an interdigitated electrode array structure which can be used both for electrical poling and subsequent electro-optic address. A contrast ratio higher than 7:1 between the on and off states is obtained with a 10-μm-thick film. A gradual variation of the contrast ratio with switching field is observed, which gives the film a capability for grey scale.
Effect of a thin Permalloy layer on bubble-domain stability
Authors: Lin Y.S.
Published: January 2004

This letter reports a theoretical and experimental investigation on the effect of placing a thin Permalloy layer atop bubble-domain materials. The Permalloy layer shifts and broadens the domain static bias field range because of the increase of bubble energy. The bias field shift effect starts diminishing in the presence of an in-plane field. The experimental observations are satisfactorily explained by an analytical model in which the magnetostatic coupling energy between Permalloy and bubble is first calculated and then extended to Thiele's stability theory by a pertubation method.
Effects of cw power on the pulsed gas breakdown threshold in argon at 10.6-μ radiation
Authors: Moody Carlton D.
Published: January 2004

When the focused beams of a pulsed CO2 laser and a cw CO2 laser were superimposed, the pulsed gas breakdown threshold was raised. It was found that the increase in the threshold was dependent on the gas pressure and cw power. When the intensities obtained with different focal diameters were compared, it was found that the cw gas breakdown threshold has a 1/r2 dependence on the radius of the focused cw power spot.
Laser-induced gas breakdown initiated by ultraviolet photoionization
Authors: Robinson A.M.
Published: January 2004

The threshold for laser-induced gas breakdown at 10.6 μm has been investigated in the presence of a spark discharge. Lowering of the threshold was observed over that measured in the absence of the spark for several gases. In argon at 100 Torr, threshold was a factor of 3.9 lower with the spark 3.7 cm from the laser-induced breakdown region.
Scaled photocount correlation of non-Gaussian scattered light
Authors: Koppel Dennis E. , Schaefer Dale W.
Published: January 2004

The photocount autocorrelation of non-Gaussian scattered laser light is discussed as a tool for the study of both very dilute or highly correlated scattering systems. A scaled photocount correlation technique is introduced and shown to produce a function directly proportional to the correlation function of the integrated scattered intensity, independent of the field statistics. This technique overcomes the serious problems of interpretation that can arise when the commonly used clipped correlation technique is applied to non-Gaussian fields. The scaled correlation technique is demonstrated experimentally with a simple scattering system, a small number of particles under uniform translational motion.
Remote spectroscopic analysis of ppm-level air pollutants by Raman spectroscopy
Authors: Hirschfeld Tomas , Schildkraut E.R. , Tannenbaum Harvey , Tanenbaum David
Published: January 2004

The design and performance of a remote Raman spectrometer are described. The unit has been tested at ranges from several hundred yards to a half-mile in full daylight under both clear atmosphere and fog conditions. Good S/N ratios were obtained for the detection of atmospheric H2O and CO2 as well as SO2 (300 ppm m) and hydrocarbon vapors (17 ppm m) in controlled sources, with a range resolution of 10 m. This is more than two orders of magnitude better than the best published results to date.
Parametric amplification and oscillation in nonlinear backward scattering
Authors: Hsu Hsiung , Yu Chung
Published: January 2004

The characteristics of backward-traveling-wave (BTW) parametric amplification and oscillation are analyzed. Effects of variations in pump excitation and interaction length on the stability of amplification, oscillation threshold, and over-all gain, etc., are discussed in detail. In this type of interaction, a BTW signal is always amplified more effectively than an FTW (forward-traveling-wave) signal. The significance of BTW interactions for large pump excitation or long interaction length is also indicated.
Use of direct overtone excitation in the measurement of the HF(v=2) deactivation rate
Authors: Bina M.J. , Jones C.R.
Published: January 2004

This letter reports the demonstration of direct optical overtone excitation of the second vibrational level of hydrogen fluoride. A unique variation of the laser-excited-fluorescence technique was employed in the experiment to achieve a significant nonequilibrium population of HF(v=2) within a room-temperature mixture of HF and argon. The HF(v=2) level was excited by a pulse from a temperature-tuned Nd:YAlO3 laser, and the resultant fluorescence was monitored. The Δv=1 fluorescence from the mixture revealed the presence of a double exponential decay. The preliminary data allow the interpretation of the two exponentials as representing the v=2→v=1 and v=1→v=0 collisional deactivations. This in turn has led to an approximate value for the ratio of the time constants of the processes of τ1/τ2=2.2±0.4.
Laser-beam writing on amorphous chalcogenide films: crystallization kinetics and analysis of amorphizing energy
Authors: Weiser K. , Gambino R.J. , Reinhold J.A.
Published: January 2004

By using laser pulses, the kinetics of crystallization of Te-rich films were studied as a function of light intensity and pulse duration. The initial devitrification was found to be temperature activated (ΔE≃1–1.6 eV), and no evidence for photocrystallization was found. Amorphizing energies for 100-nsec pulses ranged from 0.13 to 0.55 nJ/μ2, depending on the degree of crystallization. Part of this increase is due to heat-of-fusion effects, but most of it is due to increased thermal conductivity with increased crystallization.
Noise figure calculation for the Rayleigh wave amplifier
Authors: Kino G.S. , Coldren L.A.
Published: January 2004

The noise figure of a Rayleigh wave amplifier is calculated using the impedance field method of noise calculation. The coupling of noise in the semiconductor to the acoustic wave is obtained from a normal mode formula. The results indicate that relatively low noise figures should be obtainable, and that trapping phenomena can be the major source of noise excitation.