bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical gain in a neutron-induced 3He-Ne-O2 plasma
Authors: DeYoung R. J. , Wells W. E. , Miley G. H.
Published: February 2003

A single pass gain of ∼0.9% p/m (at 8446 Å in atomic oxygen) has been measured for a 3He-Ne-O2 plasma generated by the volumetric 3He(n,p)3H reaction induced by neutrons from a pulsed nuclear reactor. The plasma was contained in an optical cavity containing a chopping fan that permitted a measurement of the ratio of output 8446 Å from the normal cavity to that with the back mirror blocked. This ratio, called the unblocked-blocked ratio, was used to study the gain dependence on total pressure and concentration. The maximum gain observed was for a concentration of 0.048% O2 and 1.5% Ne, at a total pressure of 600 Torr. The peak gain remained fairly constant with neutron fluxes from 1013 to 2.5×1015 n/cm2 sec. Results of other concentration studies are also discussed. The laser medium is pumped by thermal neutrons from the Illinois TRIGA reactor that impinge on a 80-cm by 0.8-cm-i.d. glass tube containing from 50 to 800 Torr 3He-Ne-O2.
Low-loss high-purity GaAs waveguides for monolithic integrated optical circuits at GaAs laser wavelengths
Authors: Stillman G. E. , Wolfe C. M. , Rossi J. A. , Heckscher H.
Published: February 2003

Attenuation measurements in epitaxial n-GaAs waveguides of different purity have been made near the absorption edge. These measurements show that losses of less than 2 cm−1 can be achieved at energies within 50 meV of the band edge using material with ND+NA⩽2×1015 cm−3. These loss values are low enough to permit the use of GaAs waveguides in some integrated optical circuits and, in addition, are significantly lower than those published for AlxGa1−xAs waveguides of similar purity at energies comparably near the absorption edge.
New nanosecond continuum for excited-state spectroscopy
Authors: Lin Chinlon , Stolen R. H.
Published: February 2003

A new nanosecond broad-band continuum source is described. The continuum is generated by nonlinear optical processes in fiber waveguides pumped with a 20-kW 10-ns dye-laser pulse of broad spectral width (∼150 Å). The continuum has a bandwidth of several thousand cm−1 in the visible with a total power ∼1 kW. The new continuum is in many aspects superior to previously known continuum sources for nanosecond time-resolved excited-state spectroscopy.
Enhancement of the donor activity of implanted selenium in GaAs by gallium implantation
Authors: Woodcock J. M.
Published: February 2003

n-type doping levels in GaAs up to 5×1018 cm−3 have been obtained by the ion implantation of 400-keV selenium ions at 200 °C followed by 360-keV gallium ions at 200 °C. This is an order of magnitude above the maximum obtained from the implantation of selenium alone.
Epitaxial silicon solar cells
Authors: D’Aiello R. V. , Robinson P. H. , Kressel H.
Published: February 2003

p +/p/n/n+ epitaxial silicon solar-cell structures were fabricated with the n-base region intentionally graded over 2 orders of magnitude in a thickness of 35 μm. Solar cells made from these layers exhibited near-ideal I-V characteristics in the practical operating range, with an open-circuit voltage of 636 mV, fill factor of 0.79, and AM1 efficiency of 12.6%. A similar epitaxial structure containing no gradient in the n-base showed good solar-cell performance but lower open-circuit voltage (603 mV).
Influence of the altered layer on depth profiling measurements
Authors: Winters Harold F. , Coburn J. W.
Published: February 2003

A simple phenomenological theory of alloy sputtering is developed which suggests that in some instances the depth resolution of depth profiling measurements is limited by the time it takes to create a layer of altered chemical composition at the surface.
Structure relaxation spectrum of metallic glasses
Authors: Chen H. S. , Coleman E.
Published: February 2003

The structural relaxation spectra of (Pd0.6Ni0.4) 0.80P0.20 and Pd0.775Cu0.06Si0.165 metallic glasses have been obtained with a differential scanning calorimeter. The relaxation spectrum exhibits two distinguishable broad features: a low and high activation energy spectrum. The low activation energy spectrum peaks at activation energy ε≈22 kcal/mole. The intensity of the low activation energy spectrum relative to the total spectrum decreases with decreasing quenching rate. Implications of these phenomena are discussed. The observed heat of relaxation of the glasses is in fair agreement with the value calculated from viscosity data using the entropy model of viscous flow.
Ti and V layers retard interaction between Al films and polycrystalline Si
Authors: Nakamura K. , Lau S. S. , Nicolet M-A. , Mayer J. W.
Published: February 2003

Fine-grained polycrystalline Si (poly Si) in contact with Al films recrystallizes at temperatures well below the Si-Al eutectic (577 °C). We show that this interaction can be deferred or suppressed by placing a buffer layer of Ti or V between the Al film and the poly Si. During annealing, Ti or V form TiAl3 or Val3 at the buffer-layer–Al-film interface, but do not react with the poly Si so that the integrity of the poly Si is preserved as long as some unreacted Ti or V remains. The reaction between the Ti or V layer and the Al film is transport limited (∝t1/2) and characterized by the diffusion constants 1.5×1015 exp(−1.8eV/kT) Å2/sec or 8.4×1012 exp(−1.7eV/kT) Å2/sec, respectively.
Composition-ratio dependence of formation of bound states in nitrogen-implanted AlxGa1−xAs
Authors: Makita Yunosuke , Ijuin Hachiro , Gonda Shun-ichi
Published: February 2003

The formation of isoelectronic bound states in AlxGa1−xAs implanted with nitrogen has been investigated by means of photoluminescence. These bound states can be observed for compositions x≳0.29. For compositions x⩽0.31 the effect of the implantation is to decrease the emission intensity.
Fast-discharge-initiated XeF laser
Authors: Wang C. P. , Mirels H. , Sutton D. G. , Suchard S. N.
Published: February 2003

By means of fast-discharge circuitry, intense laser emission was observed from the XeF molecule at 351, 353, and 349 nm in a gas mixture of He, Xe, and NF3. The over-all electrical efficiency based on the energy deposited in the gas was 1.2%; the ’’wall-plug’’ efficiency was 0.2%. An output energy of 1 mJ was measured from a laser pulse 40 nsec in duration, yielding a peak power of 25 kW. A simple model is proposed to estimate the laser performance.
γ-ray spectra detected with HgI2 at room temperature
Authors: Puschert W. , Scholz H.
Published: February 2003

Detectors for γ rays working at room temperature were made of HgI2 grown from the vapor phase by the method of dynamic gradient reversal. These detectors show a resolution (FWHM) of 2.3–3.5 keV for 241Am γ rays (59.5 keV) with negligible effects on polarization and spectral response for counting rates up to 5000/sec. For 137Cs γ rays (662 keV), the resolution could be increased for the first time to about 50 keV, provided that the thickness of the detectors was not more than about 0.5 mm. With a quasihemispherical detector, having a better efficiency, it was also possible to obtain a 137Cs spectrum with a pronounced photopeak.
Nonlinear acoustic microscopy
Authors: Kompfner R. , Lemons R. A.
Published: February 2003

The sharply convergent acoustic beam used in the scanning acoustic microscope can provide sufficient intensity to produce strong nonlinear effects at microwave frequencies. Second harmonic acoustic radiation generated in the vicinity of the beam focus is readily detected and used to form an image of an object placed in the focal plane.
Direct observations of defects in implanted and postannealed silicon wafers
Authors: Glowinski L. D. , Tu K. N. , Ho P. S.
Published: February 2003

We have used transmission electron microscopy to study crystalline defects in Si wafers which were first implanted with Si ions to produce an amorphous surface layer and then annealed to produce epitaxial regrowth. The original high degree of crystalline perfection is not entirely recovered. In the implanted layer, small defect clusters, interstitial loops, and large half-loops have been observed. The density, distribution, and characteristics of these defects have been determined.
Pulse dispersion in multimode fibers with graded B2O3-SiO2 cores and uniform B2O3-SiO2 cladding
Authors: Cohen L. G. , Tasker G. W. , French W. G. , Simpson J. R.
Published: February 2003

Dispersion differences between B2O3 and SiO2 constituents make nonparabolic profiles optimal equalizers of modal group delays. Pulse dispersion measurements were correlated with graded refractive-index profile shapes in a systematic study of a series of multimode fibers with graded B2O3-SiO2 cores and uniform B2O3-SiO2 cladding. One of the fibers had an α≈1.77 power law exponent, which at λ≈907.5 nm wavelength caused 2σ=0.26 nsec/km full rms output pulse spreading. When expected material dispersion effects were deconvolved from the output pulse spreading, the resultant pulse width was approximately 75 times less than the result expected for a comparable step-index fiber.
Positive gain measurements on the 3350-Å continuum band of Hg2
Authors: Schlie L. A. , Guenther B. D. , Rathge R. D.
Published: February 2003

A He-Cd+ laser operating at 3250 Å and an Ar+ laser at 3511 Å and 3638 Å have been used to probe for gain on both sides of the Hg2 3350-Å (A31u→X1Σg+) continuum band in Hg vapor at a pressure of 3.75 atm that was pumped by a 1.5-MeV 600-J 20-nsec electron beam. This letter presents the first observation of positive gain on this 3350-Å band of Hg2. The results indicate that the stimulated emission cross section for this band is larger than any associated photoionization process in the Hg vapor and has a magnitude of approximately 10−18 cm2. Also, raising the temperature of the vapor above its saturation value increases the maximum value and duration of the observed gain, indicating that the population of the upper level of this transition is being fed by a temperature-dependent internal energy reservoir in the Hg.
Time-resolved pump depletion in n-InSb Raman spin-flip laser
Authors: Figueira J. F. , Cantrell C. D. , Rink J. P. , Forman P. R.
Published: February 2003

We have observed a strong transient optical absorption in n-InSb (n=1016 cm−3) induced by an intense (2 MW cm−2) 10.6-μm laser beam at 2 K. Detailed studies of the time history of the transmitted 10.6-μm beam and the spin-flip Raman laser pulse produced in the InSb show that the 10.6-μm absorption lasts for ≳100 ns, and that spin-flip lasing occurs only at the beginning of the intense portion of the 10.6-μm pump pulse and after the absorption has disappeared.
Thermal oxidation of silicon wafer with ’’striations’’ from heavy phosphorus doping
Authors: Ritchie Kim
Published: February 2003

The oxidation of heavily phosphorus doped (⩽0.001 Ω cm 〈111〉) silicon wafers yielded nonuniform oxide films at thicknesses ⩽2000 Å. The variation of the film thickness and oxidation kinetics was influenced by the dopant concentration and the associated ’’striations’’ in the silicon.
Impact ionization rates for electrons and holes in GaAs1−xSbx alloys
Authors: Pearsall T. P. , Nahory R. E. , Pollack M. A.
Published: February 2003

We have measured the impact ionization rates for electrons and holes in GaAs1−xSbx for alloys with x=0.05, 0.10, and 0.12. The results show that the ionization rates for electrons (α) and holes (β) are different and a function of Sb content. In particular, for GaAs0.88Sb0.12 electrons have the higher ionization rate with α/β=2.5, while for GaAs holes have the higher ionization rate with α/β=0.25.
Correlation between critical temperature and other electrical properties for thin tantalum films
Authors: Aguado Bombin R. M. , Neal W. E. J.
Published: February 2003

Measurements on thin tantalum films prepared by evaporation in ultrahigh vacuum show definite correlation between the critical temperature (Tc) and resistivity ratio (ρ300/ρ10). Empirical relationships are given for films having resistivity ratios in the range 1.2–6 corresponding to a thickness range 11⋅5–965 nm.
Melt removal and planar growth of In1−xGaxP1−zAsz heterojunctions
Authors: Coleman J. J. , Holonyak N. , Ludowise M. J.
Published: February 2003

Evidence is provided showing that incomplete melt removal, or wipe-off, at the conclusion of liquid phase epitaxial (LPE) In1−xGaxP1−zAsz growth results in strained pitted dark layers because of the loss in composition match between the melt and substrate. Similarly, a small amount of drag-over of one quaternary melt under a different composition melt is sufficient to cause attack of the underlying substrate (or LPE layer) and to cause local changes in the second melt destroying the composition match with the substrate. Single-layer and multilayer In1−xGaxP1−zAsz structures are shown in which incomplete melt removal causes the growth of pitted ragged nonuniform layers side by side with uniform planar layers.
High mass resolution with a new variable anharmonicity Penning trap
Authors: Van Dyck R. S. , Wineland D. J. , Ekstrom P. A. , Dehmelt H. G.
Published: February 2003

A modified Penning trap has been developed and shown to yield 100 times narrower axial resonance linewidths on electrons than that of a previous unmodified Penning trap. An extra pair of electrodes is inserted in the standard trap configuration, which effectively nulls the quartic term in the trapping potential. With existing signal-to-noise limitations, an axial frequency resolution of 0.02 ppm can be obtained. This device is particularly attractive to high-resolution mass spectrometry.
High-efficiency four-wave sum mixing in magnesium at 140 nm
Authors: Wallace Stephen C. , Zdasiuk G.
Published: February 2003

In magnesium, bound-continuum matrix elements contribute constructively to the magnitude of the third-order nonlinear susceptibility χ(3ω)(3) for sum-frequency mixing in the region of the first continuum. Thus, continuously tunable harmonic radiation in the region 140–160 nm (9000 cm−1) can be readily obtained with two dye lasers of modest power. The onset of saturation in the vacuum ultraviolent intensity at 1436 nm was not observed until incident powers ⩾30 kW, where the measured power conversion efficiency was 0.2%.
Low-loss AlxGa1−xAs waveguides grown by molecular beam epitaxy
Authors: Merz J. L. , Cho A. Y.
Published: February 2003

Low-loss AlxGa1−xAs waveguides with x=0.1 and x=0.25 have been fabricated by molecular beam epitaxy. Losses are determined for both n- and p-type waveguides using a combination of Raman scattering and transmission measurements. These waveguides have optical losses ⩽1.5 cm−1 between 1.1 and 1.4 eV, the energy of the GaAs double heterostructure laser, and are comparable to similar waveguide structures grown by liquid phase epitaxy.
Characteristics of a water absorber in front of a silicon solar cell
Authors: Chappell Terry I. , White Richard M.
Published: February 2003

In a system for converting sunlight to both electric power and heat, a selective absorber between the sun and a semiconductor solar cell may provide a substantial thermal output without seriously reducing the electrical output. Calculations for water in front of a typical silicon solar cell show, for example, that a water layer 1 cm thick absorbs 16.3% of the incident energy (chiefly photons having energies below the energy gap of silicon) while reducing the electric power output only slightly, from 13.8 to 13.1%. Experimental results confirm this finding.
Scattering of electromagnetic waves from a rough surface
Authors: Sung C. C. , Holzer J. A.
Published: February 2003

The average irradiance of reflected electromagnetic waves from a Gaussian rough surface is calculated exactly without the conventional small-slope or stationary-phase approximation. Numerical results for the one-dimensional problem are presented and compared with previous calculations.
Electroabsorption in GaAs and its application to waveguide detectors and modulators
Authors: Stillman G. E. , Wolfe C. M. , Bozler C. O. , Rossi J. A.
Published: February 2003

The electroabsorption coefficient of GaAs has been measured in uniform electric fields at wavelengths from 0.91 to 0.93 μm. These measurements were made using Schottky barrier contacts on low-loss GaAs waveguides consisting of high-purity epitaxial GaAs grown on heavily doped GaAs substrates. The experimental results are in good agreement with theoretical calculations of the Franz-Keldysh effect. Electroabsorption detectors with subnanosecond response time and 100% internal quantum efficiency have been integrated into these waveguides. Small values of avalanche gain have been obtained without any intentional guard-ring structure. Integrated electroabsorption modulators with greater than 20-dB depth of modulation were also fabricated.
Parallel diffusion constant of hot electrons in silicon
Authors: Nag B. R.
Published: February 2003

A formula is derived for the parallel diffusion coefficient of hot electrons starting from the diffusion equation derived earlier by the author. Values of the coefficient predicted for silicon from the formula are in excellent agreement with recent experimental results.
Nucleation of CuSi precipitate colonies in oxygen-rich silicon
Authors: Tice W. K. , Tan T. Y.
Published: February 2003

The nucleation of CuSi precipitate colonies in silicon containing substantial amounts of oxygen has been studied by transmission electron microscopy. It is shown that oxygen in Si can influence precipitation of Cu by generating prismatic dislocation loops at the interface between the Si matrix and oxygen-rich precipitates. Such loops act as nucleation sites for CuSi precipitates, which form star-shaped colonies upon continued solid solution decomposition.
Electro-optically switched coupler with stepped Δβ reversal using Ti-diffused LiNbO3 waveguides
Authors: Schmidt R. V. , Kogelnik H.
Published: February 2003

An experimental electro-optical switched directional coupler is reported which is formed in LiNbO3 by diffused Ti strip waveguides and uses stepped reversed phase mismatching to provide electrical adjustment of both switch states. A measured 400:1 conversion of light from one guide to the other was obtained.
Saturable transmission in mercury cadmium telluride
Authors: Matter J. C. , Smirl A. L. , Scully M. O.
Published: February 2003

We have observed saturable absorption effects in mercury cadmium telluride. The transmission of etched Hg0.39Cd0.61Te saturates by more than a factor of 10 for high pulse energies at the wavelength λ=1.06 μm. The lifetime of this short-lived saturation is measured to be less than 50 psec.
Focal properties of geodesic waveguide lenses
Authors: Verber C. M. , Vahey D. W. , Wood V. E.
Published: February 2003

The focal properties of uncorrected geodesic lenses in ion-exchanged glass waveguides are reported. A 13.8-mm-focal-length lens resolved by beams with an angular separation of 27.6 mrad, while a 28-mm-focal-length lens resolved beams with an angular separation of only 3.3 mrad. Intensity profiles of the focal region of the former lens revealed a 40-μ spot size when the input aperture was 5 mm, and a spot size of 7.7 μ when the aperture was reduced to 1 mm. This value is close to the diffraction-limited spot size of 5.7 μ.
Splicing tolerances in graded-index fibers
Authors: Adams M. J. , Payne D. N. , Sladen F. M. E.
Published: February 2003

Calculations are presented showing that, in general, a parabolic-index fiber is more sensitive to lateral misalignments within a splice than a step-index fiber. However, misalignments result in the excitation of leaky modes in graded-index fibers, and this can lead to optimistic joint loss measurements. Effective losses are given for various lengths of fiber following the splice, and it is shown that a parabolic-index fiber may appear more tolerant to misalignment than a step-index fiber when short lengths are used.
Laser action at 12.812 μm in optically pumped NH3
Authors: Chang T. Y. , McGee J. D.
Published: February 2003

Optical pumping of the aR (6,0) line of the ν2 fundamental vibrational band of NH3 has led to laser action on the aP (8,0) line at 12.812 μm of the same vibrational band. A 5-kW pulsed output has been obtained by using 1.5 MW of pump power at 9.294 μm from a CO2 laser.
Photographic observation of the path of a laser beam in a plasma
Authors: Box S. J. C. , Byszewski W. W. , John P. K.
Published: February 2003

The path of a CO2 laser beam through a plasma is photographed by an image converter camera in conjunction with an interference filter. The filter was used to isolate a silicon impurity line the intensity of which was very sensitive to changes in plasma temperature produced by the absorption of the laser energy.
Photon emission and photoionization measurements in the CO2 laser environment
Authors: Seguin H. J. J. , McKen D. , Tulip J.
Published: February 2003

Recent monochromator measurements of the photon emission and volume photoionization produced by a simple spark source within the laser gas environment are presented. Nitrogen gas is seen to dominate the ultraviolet radiation generated while carbon dioxide is shown to control the photon transmittance in the laser volume. The data clearly identify two narrow photon bands as the only useful portions, of the spark emission spectrum, in the production of volume ionization.
Far-infrared generation from a spin-flip laser
Authors: Shaw E. D.
Published: February 2003

Far-infrared emission has been observed from an InSb spin-flip Raman laser where a mode-locked TEA CO2 laser is used as the pump source. 400 μW of power are generated in 2-nsec pulses near 100 μm. This contrasts with the usual two-crystal scheme where one crystal is used to generate the Raman Stokes signal and a second InSb crystal is used as a mixer crystal. This experimental simplification allows for a much more direct evaluation of the usefulness of the spin-flip Raman laser as a source of far-infrared radiation. It is concluded that current technology permits construction of a spin-flip Raman far-infrared spectrometer tunable over about 60–125 cm−1.
Highly electronegative metallic contacts to semiconductors using polymeric sulfur nitride
Authors: Scranton R. A. , Mooney J. B. , McCaldin J. O. , McGill T. C. , Mead C. A.
Published: February 2003

The Schottky barriers formed on n-ZnS and n-ZnSe by polymeric sulfur nitride have been compared to barriers formed by Au. Barrier energies as determined by photoresponse, current-voltage, and capacitance-voltage methods show that (SN)x is approximately 1.0 eV higher than Au on n-ZnS and 0.3–0.4 eV higher than Au on n-ZnSe. We believe that this is the first report of any metallic contact more electronegative than Au.
MIS-Schottky theory under conditions of optical carrier generation in solar cells
Authors: Card H. C. , Yang E. S.
Published: February 2003

The theory of MIS-Schottky barriers and their electrical characteristics is examined for its application to solar cells. It is found that the interface behavior of contacts forward-biased by illumination is qualitatively different from that of the same contacts biased in the dark by an applied forward voltage. Observed increases due to the interfacial layer in the open-circuit voltage of the solar cell cannot therefore be associated with increases in the ’’n value’’ measured for the dark current, but rather are due to the different effects of this layer on the transport properties of majority and minority carriers. The theory predicts an optimum thickness for the interfacial layer above which the short-circuit (minority-carrier) current decreases, and the efficiency (fill factor) is degraded.
Sputtering of Au by 45-keV ions for different fluences
Authors: EerNisse E. P.
Published: February 2003

Measurements are presented of absolute sputtering coefficients S for polycrystalline Au bombarded by 45-keV ions with Zion ranging from 2 to 79. Low-fluence results taken with chemically etched Au surfaces represent the first complete set of S values taken under the nearly ideal sputtering conditions of vanishingly small ion fluence and undamaged target surface. The results confirm unambiguously the smooth monotonic increase in S with Zion as predicted by sputtering theory. High-fluence results are also obtained which are representative of implanted-target surface conditions. These results exhibit the periodic variation of S with Zion as seen in past sputtering investigations.
Single heterostructure AlxGa1−xAs phase modulator with SnO2-doped In2O3 cladding layer
Authors: Reinhart F. K. , Sinclair W. Robert , Logan R. A.
Published: February 2003

Sputter deposition of low-resistivity (0.02 Ω cm) layers of SnO2-doped In2O3 onto AlxGa1−xAs results in heterojunction barriers to either n- or p-type material. Low-loss AlxGa1−xAs waveguides with SnO2-In2O3 cladding have been fabricated. Their propagation properties can be efficiently modulated by means of the linear electro-optic effect. Phase shifts for TE modes of 160 deg/V cm were measured at a wavelength λ=0.9 μm.
Optical studies of the back-channel leakage in N-channel MOSFET on silicon-on-sapphire (SOS)
Authors: Harari Eli
Published: February 2003

Internal photoemission studies of the Si-sapphire interface of N-channel transistors fabricated on silicon-on-sapphire (SOS) indicate that the leakage current observed in such devices after exposure to ionizing radiation is due to holes trapped in the sapphire close to the silicon interface. These holes can be removed by recombination with electrons photoinjected into the sapphire from the silicon. The much smaller preirradiation N-channel leakage cannot be removed by electron photoinjection and is therefore thought to have a different origin.
Electron distribution function in electron-beam-excited plasmas
Authors: Brau C. A.
Published: February 2003

In monatomic plasmas excited by high-intensity relativistic electron beams, the electron secondary distribution function is dominated by elastic electron-electron collisions at low electron energies and by inelastic electron-atom collisions at high electron energies (above the excitation threshold). Under these conditions, the total rate of excitation by inelastic collisions is limited by the rate at which electron-electron collisions relax the distribution function in the neighborhood of the excitation threshold. To describe this effect quantitatively, an approximate analytic solution of the electron Boltzmann equation is obtained, including both electron-electron and inelastic collisions. The result provides a simple formula for the total rate of excitation.
Combined suppressive and extinction writing using M and M
A centers in Li-doped NaF
Authors: Casasent David , Caimi Frank
Published: February 2003

The photodichroism and dispersion of M and MA centers in Li-doped NaF are used in a gray-scale image recording, reading, and storage scheme, combining extinction and suppressive writing. Improved sensitivity, contrast, and the use of the same wavelength for writing and reading are the principal advantages.
Efficient high-power operation of the cw far-infrared waveguide laser
Authors: Hodges D. T. , Foote F. B. , Reel R. D.
Published: February 2003

Order-of-magnitude increases in output power and efficiency have been obtained from optically pumped FIR lasers using a new FIR waveguide laser geometry and a new output coupler. Conversion efficiencies 5–15% of the theoretical maximum are reported for several lines between 71 and 1222 μm and cw output of 400 mW at 118 μm and 40 mW at 496 μm are obtained from a laser 2 m in length. These results indicate that the stronger FIR transitions are capable of cw operation at the 0.1–1.0-W level for 100 W of CO2 pump power.
Synchronous mode locking of two cw dye lasers sharing a common amplifier medium
Authors: Couillaud B. , Ducasse A.
Published: February 2003

A double-wavelength synchronously mode-locked cw dye laser is described. This laser consists of two resonators sharing a common amplifier medium, the passive mode locking of one cavity acting as a gain modulator for the second one. When the relative lengths and internal losses of the two oscillators are carefully adjusted, pulses are shown to be generated at two independently tunable wavelengths.
New ion laser transitions in He-Au mixtures
Authors: Reid R. D. , McNeil J. R. , Collins G. J.
Published: February 2003

We have observed 20 new laser transitions when exciting a helium discharge in a gold-plated hollow cathode. The new ion laser transitions span the wavelength region from 253 to 763 nm. The behavior of laser power as a function of helium pressure and discharge current is presented. In general, the transitions have low threshold currents (<4 A), and the output power does not saturate at the limit of the discharge current. Multiline output power of 125 mW has been demonstrated in the 250–290-nm region.
SAW image scanner using transverse acoustoelectric effect in photoconductive CdS
Authors: Yamada Masayoshi , Hamaguchi Chihiro
Published: February 2003

Optical image scanning utilizing the transverse acoustoelectric effect induced by surface acoustic waves propagating on a basal plane of photoconductive cadmium sulfide is experimentally demonstrated. ’’Positive’’ high sensitivity is obtained by using a cadmium sulfide crystal known well to be an excellent photoconductor as well as a good piezoelectric material.
Electrohydrodynamic instabilities in nematic liquids of positive dielectric ansiotropy
Authors: Sussman Alan
Published: February 2003

True hydrodynamic instabilities in nematic and weakly cholesteric liquids of positive dielectric anisotropy were observed under ac excitation. Static and dynamic periodic structures occur under two regimes. The low-conductance mode is characterized by an instability threshold voltage which is independent of the driving frequency and almost independent of temperature until a transition frequency is reached. Above that transition frequency, the threshold is a field, proportional to the square root of the driving frequency and varying with temperature as the square root of the viscosity. The high-conductance mode is characterized by a field threshold at all driving frequencies. The conductance mode type is determined by both the charge relaxation frequency and the electrode spacing. The existence of a cutoff frequency for the instability lends additional support to the identification of the phenomenon as a conductance mode.
Generation of coherent anti-Stokes rotational Raman radiation in hydrogen gas
Authors: Barrett J. J.
Published: February 2003

Coherent anti-Stokes rotational Raman scattering (CARS) has been observed for the J=3→5 rotational transition in hydrogen at a Raman frequency shift of 1033.4 cm−1. The pump wavelength of 532.1 nm was provided by a frequency-doubled acousto-optic Q-switched cw krypton-arc-lamp-pumped Nd:YAG laser, and the Stokes radiation at 563.1 nm was generated by a rhodamine 6G jet-stream dye laser excited by the 532.1-nm radiation. A comparison is made of the H2 rotational CARS signal with the vibrational CARS signal produced by the 995.4-cm−1 ν2 vibrational mode of benzene.
Off-resonant infrared laser action in NH3 and C2H4 without population inversion
Authors: Chang T. Y. , McGee J. D.
Published: February 2003

Several new infrared laser lines in CO2-laser-pumped NH3 and C2H4 have been observed under conditions that preclude population inversion. The emission frequency is found to be off resonant by roughly the same amount as the pump frequency, which is consistent with the theory of Raman-type transition in a coupled three-level system.
Galvanic detection of optical absorptions in a gas discharge
Authors: Green R. B. , Keller R. A. , Luther G. G. , Schenck P. K. , Travis J. C.
Published: February 2003

An electrical signal, resulting from discrete optical absorptions, has been observed for a variety of elements, including several for which such an effect had not been previously reported. In the present case, the effect is observed as a change in the voltage across a gas discharge tube produced by irradiation with a laser tuned to the wavelength of a transition of a species in the discharge. This signal may be used—without optical detection apparatus—for spectroscopic investigations or analytical determinations of materials in the discharge. Signals were obtained for transitions of lithium, sodium, calcium, barium, uranium, neon, and helium, in commercial hollow cathode lamps, and neon and helium in conventional discharge tubes.
Crack formation in InP-GaxIn1−xAs-InP double-heterostructure fabrication
Authors: Nagai Haruo , Noguchi Yoshio
Published: February 2003

InP-Ga0.47In0.53As-InP double-heterostructure laser diodes which emit infared radiation near 1.6 μm were prepared. At 77 K, the laser threshold current density was about 2500 A/cm2. Cracking of GaxIn1−xAs epitaxial layers on InP substrates due to lattice mismatch was observed, and the composition range of GaxIn1−xAs in which no cracking occurred was found.
Thin-film Bi2WO6
Authors: Payne D. A. , Mukherjee Jahar L.
Published: February 2003

Thin films of Bi2WO6 were prepared by rf sputtering from a stoichiometric power target onto glass substrates. As deposited the films were noncrystalline, but after a low-temperature heat treatment (200 °C) the films became highly crystalline and were single phase. Data are given for the fabrication procedure and material characteristics. Profilometry measurements indicate that the films were smooth (±200 Å) and suitable for photolithography. Bismuth tungstate is a highly acentric polar material which may be used in piezoelectric and pyroelectric devices. The recrystallized films were optically transparent and interferometry measurements are reported for the determination of refractive index.
Planar and axial channeling of 800-keV As in 〈110〉 silicon
Authors: Wilson R. G.
Published: February 2003

We believe that we have observed planar channeling of As in the open {112} plane of Si by measurement of the depth distribution of electrically active As implanted in Si at 800 keV. The assumed planar-channeled distribution is sharply peaked and is found for ions directed 0.55 ° away from the 〈110〉 axis in the direction of the {112} plane. This distribution occurs 2.6 μm in depth with a FWHM of only 800 Å and contains 3% of the total 1.5×1012 cm−2 implanted As ions. The corresponding sharply peaked 〈110〉 axial-channeled As distribution occurs 5.5 μm in depth with a FWHM of 0.40 μm and contains 28% of the implanted As ions. The axial-channeling distribution degrades as the angle away from the 〈110〉 axis increases until at 0.55° the planar-channeling distribution occurs abruptly and the axial-channeling distribution nearly disappears. The electronic stopping power of Si for 800-keV As ions in the {112} plane is determined to be 1.05×10−13 cm2 eV from these data and from accurately channeled (by Rutherford backscattering) As ion ranges measured in Si from 10 to 800 keV. While the axial-channeled distribution is skewed toward the surface, the planar-channeled distribution does not appear to be skewed.
Active branching waveguide modulator
Authors: Burns W. K. , Lee A. B. , Milton A. F.
Published: February 2003

We report the observation of electrically controlled modulation in a single-mode channel waveguide branch fabricated on Ti-diffused LiNbO3. Over 55% intensity modulation has been observed for applied voltages of ±30 V with an active length of 2.9 mm. Experimental factors limiting device performance are discussed. A theoretical description of the device, based on power transfer between local normal modes, is presented and shown to be consistent with experimental results when sideways diffusion in the channels is approximately accounted for.
Observation of bulk waves in surface acoustic wave device by frequency-shift holography
Authors: Chiba Takao , Togami Yuji
Published: February 2003

The radiation patterns of bulk waves generated by an interdigital transducer and their reflection patterns at the bottom plane of a Y-cut Z-propagating LiNbO3 have been observed clearly on the crystal using a frequency-shift-holography method. The effects of polarization of the observing light of this method and the effect of roughing the bottom plane of the crystal have been studied.
Production of large warm plasmas by staged laser heating of solid targets
Authors: Greig J. R. , Pechacek R. E.
Published: February 2003

We have shown that it is possible to create a warm plasma (kTi∼50 eV) containing in excess of 1019 electrons using multistage laser heating of a solid target. The target was first irradiated by ∼-10 J Nd/glass laser prepulse, then 600 nsec later by the ∼90 J Nd/glass main pulse. After a delay of ∼4.0 μsec, the mostly un-ionized cloud of target material so created was ionized and heated by irradiation with ≳300 J from a CO2 laser pulse.
Multifilamentary Nb-Nb3 (Al,Ge) superconductors
Authors: Pickus M. R. , Dariel M. P. , Holthuis J. T. , Wang J. Ling-Fai , Granda J.
Published: February 2003

Multifilamentary Nb-Nb3 (Al,Ge) superconductors were prepared using an infiltration process. The critical temperature of sample diffusion reacted in the 1250–1700 °C temperature interval ranged from 16 to 19.0 °K. A critical current density of 105 A/cm2 at 50 kOe was observed for samples reacted at lower temperatures.
Increased domain wall velocities due to an orthorhombic anisotropy in garnet epitaxial films
Authors: Stacy W. T. , Voermans A. B. , Logmans H.
Published: February 2003

Magnetic domain wall velocities are compared for (Eu,Lu)3 (Fe,Al)5O12 films grown on (110) and (111) Gd3Ga5O12 substrates. The (110) films have an orthorhombic anisotropy which is partly stress induced and partly growth induced; the (111) films are uniaxial. Wall velocities approaching 500 m/sec have been measured in the orthorhombic films while the (111) films exhibit a maximum velocity of ∼5 m/sec. The results are compared with theoretical limiting velocities.
Ion-beam-deposited polycrystalline diamondlike films
Authors: Spencer E. G. , Schmidt P. H. , Joy D. C. , Sansalone F. J.
Published: February 2003

X-ray and electron beam diffraction analyses have been carried out on thin films deposited from a beam of carbon ions. Results show that the films consist of a polycrystalline background of cubic diamond with a particle size of 50–100 Å with single-crystal regions up to 5 μm in diameter.
Piezoelectric effect in a cholesteric liquid crystal layer subjected to shear vibration
Authors: Kagawa Yukio , Hatakeyama Toyomasa
Published: February 2003

Piezoelectric effects are observed in a mixed cholesteric liquid crystal layer. It is sandwiched by a pair of nesa-coated glass plates one of which is subjected to lateral motion to develop the shear vibration in the layer. It is found that the electric potential is generated from the layer, the frequency of which is the same as that of the exciting vibration. Three cases of the molecular orientation process for the liquid crystal layer are tested: (i) previous impression of dc voltage, (ii) lecithin application on the surfaces of the substrate glass plates, and (iii) previous static shear strain on the layer. 10–20 mV peak-to-peak (p-p) are generated for the vibratory displacement of 1 μm (p-p) of 25 kHz.
High-sensitivity acoustically scanned optical imaging device using charge storage effect
Authors: Defranould Ph. , Gautier H. , Maerfeld C.
Published: February 2003

A new principle of acoustic scanning of an optical image is described. The illumination modulates the storage time constant of a charge grating acoustically stored in a p−n diode matrix. One surface acoustic pulse directly reads out the resulting charge distribution. Owing to integration effects, the device exhibits a very high sensitivity and an electronically variable contrast.
Thermionic work function of (Cs)ZnO
Authors: Sommer A. H. , Briere T. R.
Published: February 2003

The collector electrode of a thermionic converter requires a material having a low thermionic work function and chemical stability in a Cs atmosphere in the 800 °K range. This letter reports that ZnO with an adsorbed Cs film meets these requirements. The work function is approximately 1.3 eV. Various methods of preparing the ZnO film are described as well as an experiment in which Cs was replaced by K.
Thin-film (Pb,Sn)Se photodiodes for 8–12-μm operation
Authors: Hohnke D. K. , Holloway H. , Yeung K. F. , Hurley M.
Published: February 2003

Photodiodes have been made from thin films of p-type (Pb,Sn)Se on BaF2 substrates. Surface inversion using Pb barriers has given devices with D* (10.1 μm) ≳5×1010 cm Hz1/2 W−1 and D* (11.5 μ) ≳2×1010 cm Hz1/2 W−1 at 77 K with zero-bias resistance-area products up to 2 Ω cm2. Quantum efficiencies of the best devices were about 0.5.
Second-harmonic generation in GaAs ’’stack of plates’’ using high-power CO2 laser radiation
Authors: Thompson D. E. , McMullen J. D. , Anderson D. B.
Published: February 2003

Efficient wide-band high-power generation of CO2 laser second-harmonic radiation is reported using a ’’stack-of-plates’’ approach to phase match the interaction in GaAs. A long collinear interaction length is achieved by using a series of {111} GaAs crystalline plates at Brewster’s angle, each one coherence length thick, oriented so as to alternate the sign of the nonlinear polarization in each consecutive plate. The peak second-harmonic power generated was 60 kW at 5.3 μm using 3 MW of mode-locked pump power with a stack of 12 GaAs plates. 420
Threshold instability in IGFET’s due to emission of leakage electrons from silicon substrate into silicon dioxide
Authors: Ning T. H. , Osburn C. M. , Yu H. N.
Published: February 2003

Experimental evidence of a new type of threshold instability in IGFET’s due to the emission of leakage electrons from the silicon substrate into SiO2 is presented. Also presented is a model relating the emission current to the leakage current components of the device. This emission phenomenon could be a serious threshold instability problem at high operating temperatures where the leakage current level is high, especially in devices with a dual dielectric as the gate insulator where the electron trap concentration is very high.
Bulk generation current in depleted germanium junctions
Authors: Hall R. N.
Published: February 2003

Bulk generation in buried germanium junctions has been measured in the range 77⩽T⩽160 K using a new ’’monode’’ structure which eliminates surface leakage. Above 120 K the current varies with an activation energy of 0.36 eV. At lower temperatures the generation current per unit volume is constant at 3×10−14 A/cm3 and is shown to be produced by ionization caused by cosmic and environmental background radiation.
Enhanced crystallinity of low-temperature-deposited silicon films on graphite substrates
Authors: Chang Chin-An , Siekhaus Wigbert J.
Published: February 2003

Silicon thin films (2000–3000 Å) were vacuum deposited onto graphite substrates held at 600 °C with a prior coating of an ultrathin Si-Al-Si (∼100-500-100 Å) sandwich layer. X-ray diffraction showed a considerable increase in silicon crystallinity over those directly deposited onto graphite at the same substrate temperature. The increase observed is comparable to that using quartz substrates. The distribution of aluminum in the silicon films thus deposited is determined using Auger spectroscopic depth profiling.
Atmosphere effects on Nb3Ge growth and superconductivity
Authors: Sigsbee R. A.
Published: February 2003

Quantitative improvements are observed in the Tc, resistivity ratio, and reproducibility of superconducting Nb3Ge films coevaporated in air, N2, and O2 background pressures of 10−6–10−5 mm Hg. Tc onsets above 21.5 °K and (300 °K/25 °K) resistivity ratios above 2 are achieved. Pressures above the optimum result in degraded film properties.
Effect of stress on the critical current of Nb3Sn multifilamentary composite wire
Authors: Ekin J. W.
Published: February 2003

A critical-current study of flexible Nb3Sn multifilamentary composite wires has been conducted at 4 K in magnetic fields to 90 kOe (7.2×106 A/m) while the wire is subjected to high mechanical stresses. The results show that at stresses above 1–2×108 Pa (strains of 0.1–0.2%) the critical current is significantly degraded, with the magnitude of the reduction dependent on reinforcement techniques used in the wire’s construction. The effect increases with magnetic field and results in the introduction of significant resistance at current levels well below the zero-stress critical current. Design considerations for the use of Nb3Sn wires in the high-stress environments of large-scale superconducting magnets are discussed.
Magnetization, magnetic anisotropy, and domain patterns of Fe80B20 glass
Authors: Hasegawa R. , O’Handley R. C. , Tanner L. E. , Ray R. , Kavesh S.
Published: February 2003

The thermomagnetization behavior, magnetic anisotropy, and magnetic domain patterns of ribbons of the newly synthesized Fe80B20 glass have been examined. This glass exhibits a saturation moment of 1.99 μB/Fe atom, a ferromagnetic Curie temperature of 647 K, and a crystallization temperature of ∼660 K. The direction of magnetic anisotropy lies at ∼60° to the ribbon axis in the plane of the ribbon. Large domains, elongated parallel to the ribbon axis, are observed.
Room-temperature mesa lasers grown by selective liquid phase epitaxy
Authors: Bellavance D. W. , Campbell J. C.
Published: February 2003

A new monolithic mesa laser structure grown by liquid phase epitaxy through openings in a silicon nitride mask is reported. The optical feedback is provided by vertical as-grown crystalline facets. Double heterojunction lasers have been grown with this new structure and room-temperature operation has been achieved.
Single-transverse-mode injection lasers with embedded stripe layer grown by molecular beam epitaxy
Authors: Lee T. P. , Cho A. Y.
Published: February 2003

Lateral current confinement was achieved in injection lasers with embedded stripes selectively grown by molecular beam epitaxy. A single transverse mode was obtained at currents 4–6 times threshold with a 5-μm-wide stripe.
Single-pulse coherent anti-Stokes Raman scattering
Authors: Roh Won B. , Schreiber Paul W. , Taran J. P. E.
Published: February 2003

A new technique for use in coherent anti-Stokes Raman scattering experiments allows the simultaneous generation of an entire Q-branch spectrum of the anti-Stokes radiation from a molecular gas using a single laser pulse. With this technique the stringent requirements of the previous techniques concerning laser linewidth and frequency stability are significantly relaxed. The excellent temporal resolution (20 nsec) makes the technique very attractive for temperature and concentration measurements of molecular gases, even in nonstationary media.
Intracavity second-harmonic generation in a Nd pentaphosphate laser
Authors: Chinn S. R.
Published: February 2003

We have achieved cw second-harmonic generation using an intracavity Ba2NaNb5O15 doubler crystal in a low-power NdP5O14 laser pumped by a dye laser. Our results show the feasibility of obtaining visible (0.525 μm) second-harmonic radiation from similar lasers pumped by near-infrared semiconductor sources.
Stark-tuned resonances of N15H2D with CO2 laser lines
Authors: Tangonan G. L. , Abrams R. L.
Published: February 2003

The CO2 laser spectroscopy of gas mixtures of N15H2D and N15HD2 has been studied. Four new resonances with the P (28), P (26), P (10), and R (18) lines have been observed. The applicability of these new resonances to Stark cell stabilization of CO2 lasers is discussed.
Interdiffusion between GaAs and AlAs
Authors: Chang L. L. , Koma A.
Published: February 2003

Epitaxial structures composed of thin layers of GaAs and AlAs were grown by the technique of molecular beam epitaxy. The interdiffusion coefficient was measured by Auger-electron profiling after annealing the structures under As-rich conditions over the temperature range 850–1100 °C. This coefficient was found to be extremely small, in the 10−18 cm2/sec region at the lower temperatures. It also depends on the alloy composition, decreasing with an increase in Al. Such dependence becomes stronger at higher temperatures, giving rise to activation energies of 4.3 and 3.6 eV in the limits of GaAs and AlAs, respectively.