bluuebunny/crossref_metadata_2025 huggingface dataset:
Gain spectrum of a high-pressure CO2 laser
Authors: Miller J. L. , Ross A. H. M. , George E. V.
Published: February 2003

The gain spectrum of a high-pressure uv preionized CO2 laser was measured for pressures to 14 atm. The data show an ∼10% increase in the gain of the P branch of the 961-cm−1 (00°1) - (10°0)1 band which is attributed to the overlapping 927-cm−1 0111- (1110)1 band. The measured gain was shown to be in good agreement with the theoretical predictions of a four-temperature kinetic model.
Excitation mechanism of the He-I+ laser
Authors: Shay T. , Kano H. , Collins G. J.
Published: February 2003

We have investigated the afterglow decay rates of sixteen iodine ion, I(II), laser lines in spontaneous emissions. All lines originate from the four triplet terms of the 5s25p3(2D0)6p electronic configuration. The variation of the I(II) spontaneous emission decay rates with increasing iodine pressure provides direct evidence that a charge-transfer reaction involving the ground-state atomic helium ion and a ground-state iodine atom is a primary source of excitation for the upper levels of the helium-iodine ion laser. A total velocity-averaged cross section, σ (He+-I), of 3×10−16 cm2 has been measured.
Nonlinear interaction between oppositely propagating surface waves
Authors: Padmore T. C. , Stegeman G. I.
Published: February 2003

The nonlinear interaction between two oppositely directed surface acoustic waves (SAW) is analyzed. It is shown that the surface boundary conditions lead to the generation of up to three bulk waves at the sum frequency of the two input waves. The interaction is characterized by two frequency-independent parameters which are related to the total surface displacement at the sum frequency and the strength of the bulk waves generated. These parameters are calculated for a number of materials of technological interest.
Surface acoustic wave tapped correlator using time integration
Authors: Menager O. , Desormiere B.
Published: February 2003

A new alternative to the nonlinear delay line convolver is presented, one which has the special advantage of being able to correlate millisecond signals without time inversion. An experimental verification achieved with a simple device is described and the possible use of a more complete system is explained.
Doppler-free two-photon electronic absorption of nitric oxide and benzene
Authors: Gelbwachs J. A. , Jones P. F. , Wessel J. E.
Published: February 2003

Doppler-free electronic state absorption spectra of molecules have been recorded by means of counterpropagating-beam two-photon spectroscopy. The molecular transitions that were investigated were the A2Σ+1(v=0) ←X2Π1/2 (v=0) transition of nitric oxide and the 1B2u←1A1g, 1410 transition of benzene. Linewidths observed were less than the Doppler width for each transition.
Self-compensation of donors in high-purity GaAs
Authors: Wolfe C. M. , Stillman G. E.
Published: February 2003

Column-IV (Si, Ge, and Sn) and column-VI (S, Se, and Te) impurities are used to dope high-purity layers of vapor epitaxial GaAs. Resistivity and Hall data on a large number of samples show that the common donors in GaAs (assumed to be column-IV impurities on gallium sites and column-VI impurities on arsenic sites) are compensated by acceptor centers which are donor impurity-vacancy complexes. These acceptor complexes are tentatively identified as column-IV impurities on gallium sites associated with single gallium vacancies and column-VI impurities on arsenic sites associated with single arsenic vacancies.
Photoluminescence from Be-implanted GaAs
Authors: Chatterjee Pallab K. , Vaidyanathan K. V. , McLevige W. V. , Streetman B. G.
Published: February 2003

Low-temperature (6 °K) photoluminescence data on Be-implanted GaAs are presented. A luminescence band centered at 1.4902 eV is related to recombination involving the Be acceptor. Annealing to 900 °C with Si3N4 encapsulation is shown to optically activate the implanted Be and reorder the lattice. The ionization energy of Be is estimated to be 22±3 meV.
Observation of an x-ray shuttering mechanism utilizing acoustic interruption of the Borrmann effect
Authors: Hauer Allan , Burns S. J.
Published: February 2003

Observations of acoustic interruption of x-ray transmission through a high-quality silicon crystal with a low dislocation density are described. Borrmann x-ray topographs are used to visualize the acoustic strain field. Meausrements were made of the variation of x-ray transmission vs acoustic power. The possible application of this effect as a fast acousto-optic switch mechanism is discussed.
Backscattering of keV molecular hydrogen ions from Au surfaces
Authors: Eckstein W. , Verbeek H. , Datz S.
Published: February 2003

Appreciable quantities of molecular hydrogen ions have been observed in backscattering of 5-keV D3+ from Au. At a scattering angle of 10° the D+2/D+1 ratio was 5×10−2 and D+3/D+1=2×10−4. The ratios decrease with increasing scattering angle, but D+2 is observable at angles up to 50°.
cw laser oscillation in Cu II
Authors: McNeil J. R. , Collins G. J. , Persson K. B. , Franzen D. L.
Published: February 2003

We have obtained cw laser oscillation on 23 transitions of Cu II in the blue-green and near infrared by exciting either a He-Ar, He-Ne, or a He-Xe discharge in a copper hollow cathode. The Cu II wavelengths range from 4506 to 7988 Å. Output characteristics of the Cu II laser lines as functions of helium pressure; He:Ar, He:Ne, and He:Xe mixture ratios; and discharge current are presented. Single-line output power, from the 7808-Å transition of Cu II, of 150 mW has been obtained.
Detection of core-gas ions from 3He-filled pellets in laser-driven fusion studies
Authors: Goforth R. R.
Published: February 2003

3He2+ ions from laser-irradiated 3He-filled glass microsphere targets were mass spectroscopically observed only at low velocities consistent with the predictions of hydrodynamic calculations. The null measurements at high velocity indicate that the core gas is largely contained.
Optical waveguide characteristics of reactive dc-sputtered niobium pentoxide films
Authors: Aagard R. L.
Published: February 2003

Reactively dc-sputtered films of Nb2O5 have very good optical characteristics when prepared under the proper conditions. Substrate preparation, sputtering pressure, gas composition, and deposition power have beem determined which yield films having refractive index from 2.1 to 2.27 and waveguide loss less than 2 dB/cm at 6328 Å.
A second look at the excitation mechanism of the He-Hg+ laser
Authors: Kano H. , Shay T. , Collins G. J.
Published: February 2003

We have resolved the controversy in the literature concerning the dominant excitation mechanism of the cw mercury ion laser by obtaining the first direct experimental proof that thermal energy charge transfer is the dominant formation process for the excited 7p2P terms of Hg II which support cw laser oscillation of 6150 and 7944 Å. Using a floating double probe we have monitored directly the helium ion density versus time and confirmed its one-to-one correspondence with the measured decay of spontaneous emission from the Hg II 7p2P levels. The measured value of the cross section, σ (He+-Hg), is 1.3×10−14 cm2, amongst the largest ever observed in atomic physics, and confirms earlier work by Dyson.
LPE growth of GaAs by supercooling technique: Elimination of surface terraces
Authors: Toyoda Nobuyuki , Mihara Minoru , Hara Tohru
Published: February 2003

The surface morphology of thin GaAs LPE layers grown on substrates misoriented from the (100) or (111) B plane is studied. The experiments demonstrate that surface terraces can be eliminated by using initially supercooled solutions. Very smooth surfaces are obtained for growth even on substrates miroriented 0–10° off the (100) plane.
Planar-to-homeotropic structure transition under electric field in an A-phase smectic
Authors: Hareng M. , Le Berre S. , Metzger J. J.
Published: February 2003

We have obtained a planar-to-homeotropic structure transition in a smectic-A liquid crystal under electric field. The mechanisms involved in this transition are described and explained. The most important feature is the nucleation of a new type of defect which gives rise to a network of focal conics, then to a quasihomeotropic structure.
High-pressure absorption spectrum of CO2 laser bands at 10 μm
Authors: Miller J. L. , George E. V.
Published: February 2003

The absorption coefficient at the center of several lines of the 961- and 1064-cm−1 bands of CO2 has been measured for CO2 and mixtures of CO2 and N2 and He at absolute pressures to 18 atm. The data are in good agreement with the theory of pressure-broadened non-Lorentzian overlapping lines, which predicts greater peak absorption than theories that calculate the spectrum as a sum of Lorentzian-shaped lines.
Pump absorption and saturation in the CH3F 496-μm laser
Authors: Hodges D. T. , Tucker J. R.
Published: February 2003

Results are presented from a series of diagnostic experiments designed to measure the fundamental absorption parameters in CH3F for the P (20) CO2 laser line at 9.55 μm. These parameters include the small-signal absorption coefficient, the saturation intensity for the absorbing transition, and the homogeneous linewidth. These data provide a quantitative characterization of the pumping process for the cw CH3F laser operating at 496 μm.
A fast scalable switching technique for high-power CO2 laser radiation
Authors: Alcock A. J. , Corkum P. B. , James D. J.
Published: February 2003

Fast switching of high-power 10-μm radiation by reflection from optically induced carriers in polycrystalline germanium has been demonstrated. Initial studies carried out with a single-mode TEA CO2 laser and a 2-nsec ruby laser pulse have resulted in the generation of synchronized ∼2-nsec pulses of 0.69- and 10-μm wavelength. Potential applications of this technique include the selection of single high-energy pulses from the mode-locked output of large-aperture CO2 lasers.
Low-energy ion-scattering spectrometry (ISS) of the SiO2/Si interface
Authors: Harrington William L. , Honig Richard E. , Goodman Alvin M. , Williams Richard
Published: February 2003

The interface between Si and thermally grown SiO2 has been examined in detail by low-energy 4He+ ion scattering. The oxide composition is shown to be stoichiometric to within 15–20 Å of the interface. ISS depth profiles clearly establish a region of excess Si that extends from the interface into the oxide for 15–20 Å, corresponding to four or five molecular layers. The amount of excess Si is calculated from the experimental data as 1.4×1014 atoms/cm2 per monomolecular layer (about 20% excess).
New effect in Josephson mixing of a submillimeter laser signal and a microwave signal
Authors: Henningsen J. O. , Lindelof P. E. , Steingrimsson B. S.
Published: February 2003

An oscillatory quasiperiodic structure is observed in the I-V characteristic of a Josephson point contact irradiated by a 525.5-GHz submillimeter laser signal and a 4.5-GHz microwave signal. Solving the resistively shunted Josephson (RSJ) model by a novel approach, in which the supercurrent is treated as a perturbation, the structure is shown to result from higher-order mixing processes.
Trace-element analysis of water samples using 700-keV protons
Authors: Rickards J. , Ziegler J. F.
Published: February 2003

We have evaluated the trace-element sensitivty of ion-induced x-ray analysis on residues from water samples using 700-keV protons. We find that most elements of interest can be detected in quantities below one part per billion in running times of about 3 min. We discuss in detail the necessary steps for absolute calibration of the analysis system, and the process of sample preparation in countries where high-purity substrates are difficult to obtain.
Infrared-pumped third-harmonic and sum-frequency generation in diatomic molecules
Authors: She C. Y. , Billman Kenneth W.
Published: February 2003

Using molecular hydrogen as a model system, we present the first calculation which demonstrates the feasibility of efficient third-harmonic and sum-frequency generation of ir laser radiation by diatomic molecular gases. A conversion efficiency of 10% without phase matching is achievable with a modest laser intensity of about 20 MW/cm2. In addition to a two-photon resonance, the efficient conversion depends on a mechanism which makes use of virtual vibronic transitions exclusively. Possible methods for phase matching are also suggested.
Subnanosecond relaxation time measurements using a transient induced grating method
Authors: Phillion Donald W. , Kuizenga Dirk J. , Siegman A. E.
Published: February 2003

The orientational relaxation times and S1 singlet lifetimes for Rhodamine 6G molecules in various alcohols have been measured using mode-locked laser pulses in a transient induced grating technique. The transient grating technique can be applied to measure a variety of atomic and molecular excited state phenomena on subnanosecond to picosecond time scales.
Temporal evolution of the electron density in high-pressure electron-beam-excited xenon plasmas
Authors: Zamir E. , Werner C. W. , Lapatovich W. P. , George E. V.
Published: February 2003

Measurements of the free-free absorption coefficient in high-pressure (50–400 psia) e-beam-excited rare-gas plasmas have been used to deduce the temporal evolution of electron density in these systems. The measurements were carried out using a focused CO2 laser beam passing through the excited region of the plasma. Comparison of theory and experiment in the early afterglow, where Penning ionization of excimers dominates the electron production, yields a room-temperature rate coefficient of 8×10−11 cm3/sec for this process in xenon.
Liquid-phase epitaxial growth of thin GaAs layers from supercooled solutions
Authors: Mihara Minoru , Toyoda Nobuyuki , Hara Tohru
Published: February 2003

A liquid-phase epitaxial technique using supercooled solutions free from precipitates has been developed. Excellent surface morphology and a reproducible thickness control of GaAs layers within 7% have been obtained for layer thicknesses at around 0.6 μ. This technique is readily applicable to GaAs field-effect transistors (FET’s) and other devices.
Continuous operation over 10 000 h of GaAs/GaAlAs double-heterostructure laser without lattice mismatch compensation
Authors: Kan H. , Namizaki H. , Ishii M. , Ito A.
Published: February 2003

By improving the crystal growth conditions, continuous operation over 10 000 h has been achieved with a conventional metallic stripe geometry double-heterostructure laser without using additional Al to the GaAs active region or P to the adjacent GaAlAs layers, and this laser is still being operated.
GaAs-GaAlAs distributed-feedback diode lasers with separate optical and carrier confinement
Authors: Aiki K. , Nakamura M. , Umeda J. , Yariv A. , Katzir A. , Yen H. W.
Published: February 2003

Remarkable reduction of the threshold current density is achieved in GaAs-GaAlAs distributed-feedback diode lasers by adopting a separate-confinement heterostructure. The diodes are lased successfully at temperatures up to 340 °K under pulsed operation. The lowest threshold current density is 3 kA/cm2 at 300 °K.
Defect-controlled generation in deeply depleted MOS-C structures
Authors: Small D. W. , Pierret R. F.
Published: February 2003

A model and supporting experimental evidence are presented to explain the nonlinear carrier generation rate versus semiconductor depletion width dependence which is frequently observed in the course of carrier generation lifetime (τ0) measurements. Experimental observations indicate a direct correlation between the occurrence of the nonlinear generation rate exhibited by MOS-C structures and a large Si defect concentration, thereby suggesting that, when the defect concentration is large, the carrier generation rate within a structure is totally dominated by enhanced generation from bulk centers positioned in the vicinity of defect sites.
Nitrogen reaction at a silicon–silicon dioxide interface
Authors: Raider S. I. , Gdula R. A. , Petrak J. R.
Published: February 2003

Evidence is provided indicating that a nitridation reaction occurs at a silicon–silicon dioxide interface during high-temperature annealing in nitrogen. The factors affecting nitrogen-reaction kinetics are similar to those affecting oxidation of silicon with dry oxygen. The nitridation reaction is significantly slower than the oxidation reaction, and trace amounts of oxidants can effectively compete with nitrogen for silicon reaction sites.
Lithium ammonium sulphate, a polar ferroelastic which is not simultaneously ferroelectric
Authors: Hildmann B. O. , Hahn Th. , Cross L. E. , Newnham R. E.
Published: February 2003

Lithium ammonium sulphate LiNH4SO4 has been shown to be the first of a new family of polar ferroelastic crystals which are not simultaneously ferroelectric. Stress-induced shear twin motion in the ferroic phase below 10 °C verifies ferroelasticity, and the symmetry constraints are such that the prototypic polar axis does not change. From symmetry it is shown that only seven species of fully ferroelastic nonferroelectric polar ferroics are possible. Other crystals which may show this phenomenon are discussed.
Intensity and polarization effects of a single 30-psec laser pulse on five-photon surface photoeffect of gold
Authors: Lompre L. A. , Thebault J. , Farkas Gy
Published: February 2003

A single-pulse 30-psec Nd-YAG laser was used to induce five-photon photoelectric emission from a gold metal cathode. The time and the spectral distributions were Gaussian. The pulse was selected from a mode-locked pulse train and amplified. Theoretically predicted intensity dependence curves have been obtained with a certain decrease of the photoionization probability towards the high light intensities. The measured polarization dependence shows that the photoeffect is a surface one. However, an interesting effect was found, which seems to be connected with the phase relations of the oscillating em field components.
LaB6 single-crystal tips as an electron source of high brightness
Authors: Shimizu R. , Kataoka Y. , Kawai S. , Tanaka T.
Published: February 2003

A LaB6 single crystal produced at the National Institute for Research in Inorganic Materials was used as an electron source of high brightness with a commercial-type electron probe microanalyzer (EPMA). A single-crystal tip of 0.2 mm φ×4 mm was cut out from a mother crystal of LaB6 obtained by discharge machining. The tip, held with Ta ribbons by electron beam welding, was mounted in a conventional tungsten hairpin filament holder which is commonly used in electron microscopes (CEM), scanning electron microscopes (SEM), and EPMA. Using this LaB6 emitter in an electron gun of the commercial type EPMA, JAX-3, instead of the conventional tungsten hairpin, the gun was operated under the same conditions as the tungsten hairpin: vacuum between low 10−4 and high 10−5 Torr, emission current ∼100 μA at 25 kV. It is concluded from a comparison of the scanning electron micrographs obtained with the LaB6 emitter and the tungsten hairpin that the LaB6 emitter can well be used instead of the conventional tungsten hairpins as an electron source of higher brightness for CEM and SEM even in such a low vacuum as ∼10−5 Torr for practical use.
Measurement of very short optical delays in multimode fibers
Authors: Crosignani B. , Daino B. , Di Porto P.
Published: February 2003

We describe a new method for measuring group-delay differences between the modes of an optical fiber of the order of 1 psec. This is accomplished by Fourier analyzing the intensity output of the fiber, which is fed with a quasimonochromatic signal whose frequency is linearly modulated in time. We present the results of an experiment, in which time delays of the order of 10 psec have been measured. This confirms the potential of the method for measuring dispersion in optical fibers.
Ultrasonic phase-contrast imaging
Authors: Mezrich R. , Vilkomerson D. H. R.
Published: February 2003

The phase-contrast method of visualizing transparent objects is applied to ultrasonic imaging. In this method a thin polyethylene phase plate is placed at the back focal plane of an acoustic object lens which causes velocity variations in the object to be converted to proportional amplitude variations at the image plane. Examples of the application of this method to image acoustically transparent (i.e., nonabsorbing) structures, using a recently developed system to visualize ultrasonic waves, are presented.
Transform-limited picosecond pulse generation in a synchronous mode-locked dye laser pumped by doubled Nd:YAG
Authors: Goldberg L. S. , Moore C. A.
Published: February 2003

Synchronous mode locking of a dye laser longitudinally pumped by the second-harmonic pulse train from a passively mode-locked, repetitively pulsed Nd:YAG laser has been studied. The dye laser, incorporating Fabry-Perot tuning elements, has produced intense TEM00 pulses as short as 12 psec in duration with a transform-limited bandwidth of 2 cm−1. The mode-locked dye pulses are time synchronizable with the intense Nd:YAG pulses and have been tuned from 549–727 nm using several laser dyes. Both lasing efficiency and pulse duration exhibit pronounced cavity length dependences that result from processes of gain depletion and population recycling during a pumping pulse. Pulses shorter than the pump are generated under cavity length conditions for which only gain depletion effects occur.
CO chain-reaction chemical laser
Authors: Jeffers W. Q. , Ageno H. Y.
Published: February 2003

The operation of a CO chemical laser fueled by carbon monosulfide (CS) and oxygen and pumped by a chain-reaction mechanism is reported. For CS-to-CS2 mole ratios of 2.0, the chain length is 8.5. The optical performance of this chain-reaction laser, producing specific energies of 67 kJ/lbm, is superior to the performance of previous CO chemical lasers.
Anomalous temperature effect of oxidation stacking faults in silicon
Authors: Hu S. M.
Published: February 2003

We observed an anomalous temperature effect in the growth of oxidation stacking faults in silicon. For a given oxidation time, the size of stacking faults first increases with temperature following an Arrhenius relation, reaches a peak at some temperature, and then decreases with temperature rather sharply until, finally, the faults totally vanish. The temperature above which the oxidation stacking faults vanish is dependent on the crystal surface orientation as well as on the oxidation ambients. In dry oxygen, this temperature is ∼1240 °C for {100} surfaces, ∼1220 °C for {111} surfaces, and ∼1175 °C for {1,0,11} surfaces (5° off {100}). Thus, the size-versus-temperature curve of the growth of oxidation stacking faults can be divided into two regions, which may be called the growth and the retrogrowth regions. In the growth region the growth follows a power law of (size) ∝ (time)0.8; in the retrogrowth region, the power law breaks down. The activation energy in the growth region is 2.3 eV for all surface orientations and oxidation ambients. A more complete picture of the growth of stacking faults emerges, in which the reported ’’immunity to stacking faults’’ of certain vicinal {100} surfaces is merely a point far out in the retrogrowth region.
Electron microscopic observations of coherent boundaries in γ- (Cu-Al)
Authors: Torres V. Gabriel , Radcliffe S. V.
Published: February 2003

Electron microscopic evidence is obtained for the presence of a possible two-phase structure inside the γ-phase field of the Cu-Al system. Alloys with composition 34.54 at.% Al show a banded microstructure. When the bands are observed edge on adjacent plates differ in brightness. They are visible as fringe patterns when lying in planes inclined to the foil plane. Electron diffraction experiments show that the only crystallographic difference between two adjacent plates is the size of the unit cell. The probable composition of the coexisting phases is suggested to be Cu9Al4 and Cu17Al9.
Controlled-inversion transistors
Authors: Kroger H. , Wegener H. A. R.
Published: February 2003

Current-voltage characteristics similar to those of a semiconductor-controlled rectifier have been observed in three-terminal devices which have only a single p-n junction. The structure investigated is a layered sequence of metal/conducting ’’insulator’’/p-silicon/n+-silicon with electrical terminals at the metal and both sides of the junction. If a positive bias is applied to the metal the device can reside in either a low- or a high-impedance state. These states are brought about by controlling the presence or absence of the inversion layer at the insulator-silicon interface. Experimental data demonstrate the efficiency of this control permitted by the third intermediate terminal.
Nonlinear propagation of void front during electromigration in alloy films
Authors: Ho P. S. , Howard J. K.
Published: February 2003

Void formation during electromigration has been observed near the anode edge of a Cu-Al zone in an Al stripe. Growth of new voids was continuous with a void front propagating along the electron flow direction at a nonlinear rate. Such motion of the void front can be quantitatively correlated to the electromigration of Cu at grain boundaries. The measured displacements of the void front were analyzed to yield the grain-boundary diffusivity and effective charge for Cu electromigration.
High-field conduction and breakdown in liquid sulfur
Authors: Proud J. M. , Auborn J. J.
Published: February 2003

The absence of C-H bonds in aprotic and particularly in molecular liquids possessing a wide liquid range enhances the probability of observing α processes in these liquids. Evidence for electron multiplication and breakdown in the liquid phase of sulfur is presented. Current-voltage nonlinearities and the bubble-free development of electrical discharges are observed.
Diagnostics of a stationary MPD-type plasma jet with a HCN laser interferometer
Authors: Graser Wolfram , Hoffmann Peter
Published: February 2003

A HCN laser interferometer of the Ashby-Jephcott type operating at a wavelength of 337 μm was used to measure spatially resolved electron densities in a stationary MPD-type plasma jet with non-LTE behavior. Experiments were performed with and without superimposed magnetic fields up to 0.1 T at the exit of the plasma accelerator. Electron densities were obtained within the limits of 5×1012 and 1015 cm−3 with an accuracy better than 10%. Within the axially symmetric expanding plasma of about 15-cm average diameter and 50-cm length the radial resolving power came to less than 1 cm. So this technique has proved to be suitable to fill a gap in the diagnostics of stationary magnetized plasmas in the mean range of electron densities.
Population inversions in atomic cesium in the cesium-fluorine reaction system
Authors: Hall Lawrence H.
Published: February 2003

The chemiluminescence of the electronically excited cesium atom in the cesium-fluorine reaction system was analyzed to give relative excited-state populations. Pumping rates into each state have been calculated. The populations measured show 27 population inversions on optically allowed transitions.
Self-imaging in homogeneous planar optical waveguides
Authors: Ulrich R. , Ankele G.
Published: February 2003

The formation of one-dimensional self-images in planar optical waveguides is described ray optically and is demonstrated experimentally. The self-images can be erect or inverted, single or multiple, and magnified or demagnified. Possible applications in integrated optics include a cross over of strip guides, a simple 3-dB directional coupler, and a filter.
Ionized Zn doping of GaAs molecular beam epitaxial films
Authors: Naganuma Mitsuru , Takahashi Kiyoshi
Published: February 2003

Molecular beam epitaxial growth of GaAs with an ionized Zn beam as dopant is reported. In the normal molecular beam epitaxy, the sticking coefficient of Zn is nearly zero and Zn has not been used as a dopant. By ionizing the Zn atoms, a sticking coefficient of ∼0.03 was obtained, and this value is much larger than that of any other p-type dopants for GaAs except for Ge which is amphoteric.
Double-wavelength laser
Authors: Lotem Haim , Lynch R. T.
Published: February 2003

A new technique is reported which allows a laser to operate simultaneoulsy at two or more wavelengths from a high-gain grating- or prism-tuned laser. This is done by inserting a small-angle wedge in the laser to form two independent cavities. The relative intensities at the output wavelengths are governed by the wedge location. Tuning of the new wavelength is accomplished by rotating the wedge. The difference frequency between the two output wavelengths is not limited by the gain characteristics of the active medium since different active media can be used simultaneously. The wedge technique was used in a nitrogen-laser-pumped dye laser and the usefulness of such a laser in nonlinear opitcal experiments was shown.
Saturation effects in a tunable coherent near-infrared source
Authors: Tyler Israel L. , Alexander R. W. , Bell R. J.
Published: February 2003

A saturation effect in a tunable infrared source utilizing four-wave parametric conversion in potassium vapor is reported and is shown to be the result of parasitic oscillations. A hundredfold increase over previously attained power levels has been effected via elimination of these oscillations.
Generation of single-picosecond dye laser pulses using one- and two-photon traveling-wave excitation
Authors: Rubinov A. N. , Richardson M. C. , Sala K. , Alcock A. J.
Published: February 2003

Single-photon and two-photon traveling-wave excitation of superradiant emission in Rhodamine 6G by single-picosecond 1.06-μ laser pulses is reported. In addition, results are presented on the application of optical Kerr-effect photography to a time-resolved spectroscopic study of the dye laser emission.
Photoluminescence of boron-implanted AlxGa1−xAs (x=0.37)
Authors: Makita Yunosuke , Gonda Shun-ichi
Published: February 2003

Optical characteristics of B (group-III) isoelectronic impurity in AlxGa1−xAs (x=0.37) are investigated by photoluminescence measurements. Two new bands are observed at 2 K in B-implanted and annealed AlxGa1−xAs. One band is at 167.4 meV below the edge emission line, the other at 23.5 meV. The latter is observed clearly only through time-resolved spectroscopy, because the donor-acceptor pair emission almost overlaps the band. These observations suggest that the B impurity makes bound states in AlxGa1−xAs.
cw operation of distributed-feedback GaAs-GaAlAs diode lasers at temperatures up to 300 K
Authors: Nakamura M. , Aiki K. , Umeda J. , Yariv A.
Published: February 2003

Distributed-feedback GaAs-GaAlAs diode lasers with separate optical and carrier confinement have been successfully operated under dc bias up to room temperature. They lased in a single longitudinal mode with a threshold current density of 0.94 kA/cm2 at 170 K and 3.5 kA/cm2 at 300 K.
Raman studies of the electro-optic properties of CuX (X=Cl, Br, I) multicrystallite samples
Authors: Ben-Amar A. , Wiener-Avnear E.
Published: February 2003

A measurement of the Raman scattering efficiencies from an ensemble of random-oriented cyrstallites provides a method for evaluating the electro-optic coefficients in CuX (X=Cl, Br, I) binary zinc-blend semiconductors. A systematic trend in the values of both the electronic and ionic contributions to the nonlinear response is found to be related to the ionicities in these crystals.
Subpicosecond chronoscopy
Authors: Bradley D. J. , Sibbett W.
Published: February 2003

Subpicosecond time resolution with a new design of the electron-optical streak camera (the Photochron II) is demonstrated with ultrashort Raman pulses.
Conditions for shock vaporization of metals
Authors: Hornung K. , Michel K. W.
Published: February 2003

We briefly describe the method and communicate the results of a number of calculations concerning the shock vaporization of different metals which are of practical interest for atmospheric and ionospheric vapor releases (Li, Na, Sr, Ba, Pb, Eu, Fe, and U). The calculations include the determination of shock-wave entropies and residual temperatures, as well as a model description of the vaporization process upon expansion of the released material into vacuum. The results contain explicit values for the degree of vaporization from the onset up to conditions corresponding to critical entropy, depending upon shock strength.
Particulate semiconductor solar cells
Authors: Weisberg L. R. , Grain C. F. , Addiss R. R.
Published: February 2003

A new method of fabricating solar cells is proposed, namely, using particulate semiconductor layers deposited in a binder by high-speed emulsion coating technology. The feasibility of this approach was demonstrated by the fabrication of a solar cell using particulate ZnO layers with over 50% quantum efficiency, and 3% power conversion efficiency, to uv light.
Lanthanum beryllate: A new rare-earth ion laser host
Authors: Morris R. C. , Cline C. F. , Begley R. F. , Dutoit M. , Harget P. J. , Jenssen H. P. , La France T. S. , Webb R.
Published: February 2003

Optical quality crystals, measuring up to 2.5×20 cm, of the compound La2Be2O5 : Nd3+ have been grown from the melt. The results of physical- and optical-property measurements and laser testing (long pulse, Q switched, and cw mode) are reported. Linearly polarized laser oscillations at 1.07 and 1.08 μm are observed. Long-pulse slope efficiencies about 60% greater than for YAG : Nd at comparable pumping thresholds and Q-switched energy storage nearly three times that of YAG : Nd are also observed.
Picosecond-gated optical amplifier
Authors: Busch G. E. , Greve K. S. , Olson G. L. , Jones R. P. , Rentzepis P. M.
Published: February 2003

A picosecond-gated optical amplifier (PGOA) characterized by high gains (≳102), large extinction ratios (∼105), and short aperture times (∼10 psec) is described. The active component of the system is a saturable absorbing dye which is irradiated by a high-intensity ultrashort laser pulse. The technique is illustrated by simultaneously gating and amplifying a weak picosecond continuum pulse propagating through a scattering medium. Performance characteristics of the PGOA and ultrafast shutters are compared.
Intense laser emission at 3577 Å using N2-SF6 mixtures in a TE nitrogen laser
Authors: Itani Junichi , Kagawa Kiichiro , Kimura Yoshitake
Published: February 2003

Intense laser emission at 3577 Å (v′=0 of the C3πu state to v″=1 of the B3πg state of the nitrogen molecule) has been demonstrated to take place by an addition of a large quantity of SF6 as a foreign gas in a transversely excited nitrogen laser. The output at 3577 Å is increased with increasing partial pressure of SF6, until a total pressure of up to 250 Torr. With sufficient SF6 added, the output at 3371 Å is increased by a factor of 1.3 as compared with the case of N2 gas alone.
Etched buried heterostructure GaAs/GaAlAs injection lasers
Authors: Burnham R. D. , Scifres D. R.
Published: February 2003

An injection laser is described in which a semicircular GaAs active region is completely surrounded by Ga1−xAlxAs by using selective etching and a single liquid-phase epitaxial growth.The active region dimensions can be made much more symmetric than those obtained with conventional stripe geometry lasers resulting in improved optical characteristics and low room-temperature threshold currents.
Pulse shortening and pulse deformation in a high-power iodine laser amplifier
Authors: Skribanowitz N. , Kopainsky B.
Published: February 2003

Pulse propagation in a photodissociative iodine laser amplifier is investigated both experimentally and numerically. Pulse reshaping and shortening occur in agreement with theory. It is found that pulse shortening by gain saturation is impractical for subnanosecond pulses.
Steady-state excitation of a sodium beam using a cw laser
Authors: Carter Gary M. , Pritchard David E. , Ducas Theodore W.
Published: February 2003

We demonstrate a method for maintaining a large fraction (≳17%) of an atomic sodium beam in an excited state. The method uses the Doppler shift to produce, from a single-frequency laser source, a frequency spectrum which prevents optical pumping of the atoms into either of the hyperfine levels of the ground state. A small magnetic field is used to prevent pumping into a magnetic sublevel of the ground state. The method may be used for both the P1/2 and P3/2 fine-structure levels.
Production of intense deuteron beams
Authors: Golden J. , Kapetanakos C. A.
Published: February 2003

Results are reported on the production of 400-keV 50-nsec-duration 1.3-kA deuteron beams using a reflex triode.
Laser-induced dissociation of ozone and resonance fluorescence of OH in ambient air
Authors: Wang Charles C. , Davis L. I. , Wu C. H. , Japar S.
Published: February 2003

In the measurement of hydroxyl (OH) concentrations in air using the technique of resonance fluorescence, it was established that the presence of ambient ozone led to significant interference. It is concluded that this is a result of OH formation due to laser-induced dissociation of ozone. A reduction in the power density of excitation was required to reduce this effect to a negligible level.
Observation of a dynamical central peak in the light-scattering spectrum of a glass
Authors: Firstein L. A. , Cherlow J. M. , Hellwarth R. W.
Published: February 2003

We report the first observation of a dynamical central peak in the light-scattering spectrum of a glass (Schott LaSF-7). After an iodine-vapor filter had removed the elastically scattered component, the spectrum of the light scattered by the glass still exhibited a component centered between the two Brillouin lines.
Electro-optical properties of amorphous As2Se5-silicon heterojunctions
Authors: Alonso B. , Piqueras J. , Muñoz E.
Published: February 2003

The properties of heterojunctions between As2Se5 amorphous films and monocrystalline silicon are studied. The As2Se5 films behave as a memory-type switch, and the I-V characteristics of the heterojunctions on n-type Si are asymmetric but not clearly rectifying. Short-circuit photocurrent has been investigated in detail, and a band model is presented.
XeBr exciplex laser
Authors: Searles S. K.
Published: February 2003

Laser emission from the recently discovered XeBr exciplex laser was investigated as a function of the partial pressures of Xe and Br2. An optical loss process appears to limit high-pressure operation.
Infrared absorption limits of HF and DF laser windows
Authors: Hass M. , Harrington J. A. , Gregory D. A. , Davisson J. W.
Published: February 2003

The infrared absorption coefficients of NaCl, KCl, NaF, CaF2 and BaF2 have been determined by calorimetric techniques at the laser wavelengths 1.06, 2.7, and 3.8 μm. The absorption level of the best crystals can be 10−5 cm−1 or lower at l.06 μm, but no crystal with a coefficient lower than 10−4 cm−1 at 2.7 and 3.8 μm has been found. Possible reasons for these results are discussed.
Temporal stability of unstable resonator with crossflow
Authors: Mirels Harold
Published: February 2003

The temporal stability of the output from a cw laser that contains an unstable resonator with crossflow is investigated for cases where the population inversion is partially due to a pumping mechanism within the resonator. For resonator magnification M near 1, the output is shown to be stable when G0(1) <1 and dP/dζ⩾0, where G0(1) is the ratio of inlet to optical axis gain, and (−dP/dζ) is the steamwise gradient of the volumetric pumping. For arbitrary M and φ≫1, laser output fluctuations are at most of order φ−1, where φ is a measure of the net gain due to pumping divided by the threshold gain. by the threshold gain. by the threshold gain.
Capillary liquid epitaxial growth of LiNbO3 and LiTaO3 single-crystal thin films
Authors: Fukuda T. , Hirano H.
Published: February 2003

A new technique using capillary action, capillary liquid epitaxial (CLE) technique, is described for growing a high-quality LiNbO3 thin film onto a LiTaO3 substrate. A LiTaO3 single-crystal film, 2 μm in thickness, was also successfully grown with good epitaxy onto a LiNbO3 substrate by this technique. Evaluation of these films by x-ray measurements and preliminary experimental results on optical waveguide are reported.
Strength of 0.04–50-m lengths of coated fused silica fibers
Authors: Kurkjian C. R. , Albarino R. V. , Krause J. T. , Vazirani H. N. , DiMarcello F. V. , Torza S. , Schonhorn H.
Published: February 2003

Tensile strength measurements have been made on coated fused silica fibers at gage lengths up to 50 m. At gage lengths between 0.04 and 10 m, the average strength is essentially constant at about 5 GN/m2 (700 ksi). At gage lengths greater than 20 m the length dependence becomes important and by 50 m the strength has decreased to about 2 GN/m2 (300 ksi). The minimum strength recorded in the testing of samples taken continuously from a length of 1031.6 m was 0.43 GN/m2 (64 ksi). A ’’weakest link’’ model appears to be obeyed.
Vacuum-ultraviolet-induced space charge in Al2O3 films
Authors: Powell R. J.
Published: February 2003

The spectral dependence of positive space charge induced in an Al-Al2O3-Si MOS structure shows a sharp threshold at 7.8±0.2 eV. This threshold is interpreted to be the onset of band-to-band transitions in Al2O3. The net space charge induced by 10.2-eV radiation can be positive or negative depending on the bias polarity and magnitude. The voltage dependence is qualitatively explained by the competitive processes of electron-hole pair generation and electron injection from the electrodes.
Phase-matched second-harmonic generation in solid thin films using modulation of the nonlinear susceptibilities
Authors: Chen B. U. , Ghizoni C. C. , Tang C. L.
Published: February 2003

Phase-matched second-harmonic generation in solid thin films has been achieved by using gratings etched onto the surface of a nonlinear substrate to modulate the nonlinear susceptibility.
Discharge pumping of the Br2* laser
Authors: Ewing J. J. , Jacob J. H. , Mangano J. A. , Brown H. A.
Published: February 2003

Laser action on the E→B band of molecular bromine at 292 nm has been observed in an E-beam-controlled discharge. The laser mixture was 99.6% Ar and 0.4% Br2 at a pressure of 4 atm. The mean discharge current and voltage were 25 A/cm2 and 11 kV/cm, respectively. The high-energy E-beam current density was 1.5 A/cm2. The mechanisms for creating Br2* in a discharge are discussed.
Properties of the interface charge inhomogeneities in the thermally grown Si-SiO2 structure
Authors: Ziegler K. , Klausmann E.
Published: February 2003

Measurements of the standard deviation σs of the surface potential fluctuations in MOS structures were performed by the conductance technique of Nicollian and Goetzberger for different temperatures and surface potentials. The values of σs were compared with the three-dimensional mathematical model suggested by Brews and the quasiuniform model of the surface potential fluctuations generated by interface charge inhomogeneities. Good agreement was obtained with the model of Brews. We conclude that the interface charges are not agglomerated in the form of charge islands but are more or less evenly distributed. For the lower limit of the minimum wavelength of the interface charge inhomogeneities, we obtain a value of 75 Å. The upper limit of 100 Å as assumed by Brews seems to be reasonable. Negative interface charges are either absent or at most present at a low level.
Statistical characterization of the lifetimes of continuously operated (Al,Ga)As double-heterostructure lasers
Authors: Joyce W. B. , Dixon R. W. , Hartman R. L.
Published: February 2003

The statistical distribution of lifetimes of routinely grown and fabricated continuously operated (Al,Ga)As double-heterostructure lasers is presented and discussed. The 90 typical devices studied were operated as lasers in a dry-nitrogen elevated-temperature ambient (70 °C) until failure. The resulting median life, τm=750 h, and mean life, 〈τ〉=1370 h, extrapolate to τm=5.7 years and 〈τ〉=10.5 years at room temperature (22 °C) using a 0.7-eV activation energy. The observed lifetimes are consistent with a model in which 17% of the lasers die prematurely as infant mortalities while 83% die by a mechanism well characterized by a lognormal distribution. The value of the standard deviation (σ=1.1) in lnτ is typical of other semiconductor devices.
Palladium/cadmium-sulfide Schottky diodes for hydrogen detection
Authors: Steele Martin C. , MacIver Bernard A.
Published: February 2003

The barrier height of a Pd-CdS Schottky diode is reported to decrease markedly when exposed to hydrogen. This effect is believed to be due to the decrease in Pd work function. It makes a good simple hydrogen detector (even at 298 °K) over the range 500–5000 ppm H2.
Multimode achromatic electro-optic waveguide switch for fiber-optic communications
Authors: Soref R. A. , McMahon D. H. , Nelson A. R.
Published: February 2003

A three-port multimode electro-optic switch has been fabricated in a thin c-cut plate of LiNbO3 using opposed stripe-and-plane electrodes to create field-induced channel waveguides. Fringing electric fields provided multimode optical coupling between channels. Using butt coupling to connect the device into a multimode fiber link, voltage-controlled switching of laser and white-light radiation have been demonstrated.
Optical transistor
Authors: Jain K. , Pratt G. W.
Published: February 2003

A device is proposed which is the optical analog of the transistor wherein a weak incoming optical signal directly controls a strong outgoing optical signal. The basic principle utilized in the proposed device is the strong dependence of second harmonic generation on the phase-matching condition. A weak incoming signal can perturb the indices of refraction in a birefringent material so that the second harmonic power derived from a pump beam is significantly affected. Large incremental power gain is shown to be possible. Tellurium is considered as an example.
Hard wall sections in gradient-propagated magnetic bubble domains
Authors: Ju Kochan , Zimmer G. J. , Humphrey F. B.
Published: February 2003

Using high-speed photography to investigate the transient response of bubbles to a bias field pulse, a shift in the geometrical center has been related to the previous propagation history. For left (right) skew bubbles, a low-mobility section appeared at the left (right) side of the previous propagation direction. The location of the hard wall section in respect to the propagation direction agrees with Thiele’s vertical Bloch line theory. Applying this method to low-angle propagators, i.e., bubbles with few Bloch lines, an asymmetric expansion was found after propagation in a gradient drive field that was higher than a certain threshold. For these bubbles, hard wall sections of oppositely wound vertical Bloch lines pinned the two flanks of the bubble and reduced the mobility of the rear allowing the front to expand out asymmetrically. These vertical Bloch line bundles with opposite sense were generated in the front and rear, then clustered on the two flanks during the gradient propagation, consistent with a dynamic converion model.
Uniform-carrier-concentration p-type layers in GaAs produced by beryllium ion implantation
Authors: Donnelly J. P. , Leonberger F. J. , Bozler C. O.
Published: February 2003

Multiple-energy Be+ ion implantation has been used to create uniform-carrier-concentration p-type layers (≳1.5 μm thick) in GaAs. The implanted samples were annealed at 900 °C using pyrolytic Si3N4 as an encapsulant. High activation of the implanted Be was observed. On samples with implanted hole concentrations of 2×1018/cm3, the measured carrier concentration as a function of depth is in good agreement with that expected from LSS range theory. For higher doses, diffusion of the implanted Be was observed. p+n−n+ junctions formed by implantation into undoped epitaxial material have low leakage currents and sharp breakdowns at average electric fields in the n− region of 1.5×105 V/cm.