bluuebunny/crossref_metadata_2025 huggingface dataset:
Room-temperature cw operation of GaInAsP/InP double-heterostructure diode lasers emitting at 1.1 μ m
Authors: Hsieh J. J. , Rossi J. A. , Donnelly J. P.
Published: February 2003

Room-temperature cw operation has been achieved for stripe-geometry double-heterostructure Ga0.12In0.88As0.23P0.77/InP diode lasers emitting at 1.1 μm. The heterostructures were grown by liquid-phase epitaxy on melt-grown InP substrates, and stripes were defined by using proton bombardment to produce high-resistance current-confining regions.
uv TEA laser with 760-Torr N2
Authors: Bergmann Ernest E.
Published: February 2003

A simple reliable transversely excited atmospheric (TEA) laser operating with moderate repetition rates at 337 nm using commercial-grade N2 at 1 atm is described. Preliminary results for a range of operating voltages and channel spacings are presented. The laser’s pulse width is about 1 nsec. Best electrical efficiency to date is 0.039% at 8.8 kV. At 21 kV, 355 μJ/pulse is obtained. Above 16.7 kV, the unfocused output will pump a dye solution to superradiance at a distance of 1.5 m. For supply voltages less than 10 kV, a novel configuration for preionization is described.
Xenon fluoride laser excitation by transverse electric discharge
Authors: Burnham R. , Harris N. W. , Djeu N.
Published: February 2003

Stimulated emission has been produced in mixtures of He, NF3, and Xe at total pressures between 300 and 1000 Torr. Laser emission was on lines at 3511 and 3531 Å which have been associated with the excited XeF molecule. Excitation of the gas mixture was by a transverse electric discharge which produced pulses with peak currents of approximately 104 A and rise times of 20 ns. A maximum laser energy of 7 mJ was obtained from a gas mixture with a ratio of He:Xe:NF3 of 98.0:1.5:0.5 at a total pressure of 300 Torr.
dc-excited and sealed-off operation of the optically pumped 546.1-nm Hg laser
Authors: Artusy Max , Holmes Neil , Siegman A. E.
Published: February 2003

The optically pumped Hg laser at 546.1 nm, first developed by Djeu and Burnham, has now been operated as a sealed-off rather than continuously flowing system, and with dc-excited rather than rf-excited pump lamps in both elliptically focused and close-wrapped configurations. Laser power outputs of ∼1 mW cw have been obtained with ∼100 W excitation into two commercial Hg germicidal lamps, and a power output of ≳3 mW has been obtained from a sealed-off tube with ∼300 W into a single low-pressure ’’Toronto arc’’ pump lamp. Sealed-off operation appears to be stable and long lived, and substantial further performance improvements are expected.
Elastically enhanced nonradiative recombination at AlxGa1−xAs-GaAs heterointerface
Authors: Johnston W. D. , Logan R. A.
Published: February 2003

In the presence of an elastic strain gradient of order 10−5 μm−1, the nonradiative recombination rate at an (LPE) AlxGa1−xAs-GaAs heterointerface is observed to increase, reversibly, by as much as 100-fold.
Guided acoustic-surface-wave filters
Authors: Tiersten H. F. , Smythe R. C.
Published: February 2003

A number of filter structures utilizing acoustic surface waveguides and periodic arrays of reflecting strips to form multimoded resonant configurations are described. The devices described are analogous to the monolithic crystal filter in that an array of acoustically coupled resonators is obtained from a structure placed on a single substrate. The coupling between resonators is described in terms of trapped energy modes of the surface-waveguiding structures.
Observation of level anticrossing in nonlinear absorption
Authors: Sakai Jun , Katayama Mikio
Published: February 2003

Stark-tuned level anticrossing between hyperfine levels was observed in the nonlinear absorption of the CD3I ν2 QP (4,1) transition by using the CO2 laser line. Good agreement between the theoretical and the observed linewidth was obtained.
Taper coupling between 7059-glass and CdS films and phase modulation in the composite waveguide structure
Authors: McMurray J. A. , Stanley C. R.
Published: February 2003

Coupling between planar 7059-glass and CdS optical waveguides has been demonstrated. The CdS–7059-glass films form part of a multilayer electro-optic phase modulator, the first such device to be reported which uses polycrystalline films evaporated on to amorphous substrates. The behavior of the modulator structure is completely accounted for when dielectric relaxation effects in CdS films are considered.
Free-exciton radiation from p-i-n diodes of GaP doped with indium and oxygen
Authors: Tanaka Akira , Sukegawa Tokuzo , Nikaido Tadanobu , Hagino Minoru
Published: February 2003

GaP diodes containing indium and oxygen emitted intense green light (2.23 eV) with weak red light (1.77 eV) at room temperature. The green light emission was enhanced by In and the spectral measurements revealed the green light to be due to the simultaneous annihilation of a free exciton and a LA phonon. The diode had a p-i-n structure, and the green light was emitted from the intrinsic region which was formed by oxygen deep donors. At appropriate oxygen concentrations, diodes which emit only green light were fabricated successfully.
Narrow-band picosecond pulses from an ultrashort-cavity dye laser
Authors: Fan B. , Gustafson T. K.
Published: February 2003

Narrow-band picosecond pulses have been generated by a 50-μ-long Rhodamine B laser pumped by the second-harmonic output of a passively mode-locked Nd : glass laser.
Ultraviolet laser action from Cu II in the 2500-Å region
Authors: McNeil J. R. , Collins G. J. , Persson K. B. , Franzen D. L.
Published: February 2003

We have obtained cw laser action from Cu II at 2486, 2506, 2591, and 2599 Å by exciting a neon discharge in a copper hollow cathode. We have observed 7-mW cw output power just above threshold and the output appears to saturate at 210 mW under quasi-cw operation. The four ultraviolet laser lines observed originate from the 3d95s (3D) term of Cu II. The quantum efficiency of the 2500-Å laser transitions approaches 25%. Each of the four Cu II laser transitions has been employed in the past by spectroscopists as a secondary wavelength standard in the ultraviolet.
A potential high-efficiency Cl2 ultraviolet laser
Authors: Chen C. H. , Payne M. G.
Published: February 2003

An emission band extending from 2200 to 3000 Å has been observed following proton beam excitation of Ar-Cl2 mixtures which is much more intense than the emission from Ar-N2. The emission band was assigned to a bound-free transition in the chlorine molecule. The energy precursor of excited Cl2 is the excimer Ar2* which emits a 1300-Å continuum. Ion-ion recombination can also contribute to this excited chlorine molecule. The emission continuum near the 1750 Å associated with ArCl* was also investigated.
Time behavior of second-positive emissions from a fast-discharge N2+SF6 laser
Authors: Akins Robert P. , Lin Shao-Chi
Published: February 2003

The time behavior of spectrally resolved N2 second-positive emissions recently observed in our fast-discharge N2+SF6 laser reveals some surprising features that cannot be explained on the basis of SF6-catalyzed vibrational relaxation or collisional quenching of the lower-laser-level B3Πg. Instead, they suggest the existence of an extremely fast excitation process for the upper-laser-level C3Πu involving SF6 as an intermediary, although the kinetic path for such a process remains unclear.
Schottky barrier heights of nickel-platinum silicide contacts on n-type Si
Authors: Terry L. E. , Saltich Jack
Published: February 2003

The barrier heights of NiPt silicide–n-type Si have been determined from the saturation current density of diodes for various concentrations of Ni and Pt. Ni-Pt films on Si were heated to 475 °C to obtain a NiPt silicide. The barrier height varies smoothly from that of NiSi-Si to PtSi-Si with increasing amounts of Pt in the NiPt films. For 19 wt% Pt the barrier is 0.69 eV and for 67 wt% Pt the height is 0.78 eV.
Anomalous migration of ion-implanted Al in Si
Authors: Dietrich H. B. , Weisenberger W. H. , Comas J.
Published: February 2003

Depth profiles for 60-keV Al+ implanted in Si have been measured by SIMS analysis as a function of implant fluence and anneal temperature. A pronounced structure has been observed in the annealed profiles for fluences ⩾1015 cm−2. Comparison of the Al profiles with those of implanted B and Ga established that the structure is species dependent. The results of measurements designed to isolate damage effects indicate that the observed structure is induced by the reordering of the amorphous layer.
Gaseous saturable isolator for a high-gain CO2 amplifier chain
Authors: Lavigne P. , Lachambre J. L. , Gilbert J.
Published: February 2003

The use of a combination of gaseous N2F4 and C2H5OH in interstage optical isolators is reported to prevent self-oscillation of a TEA-CO2 amplifier chain. The results of a preliminary measurement of the absorption and saturation characteristics of N2F4 are presented. Single nanosecond pulses of 15 J are stably generated by inserting two such isolators along a 120-dB amplifier chain.
Stress-induced effects in sputtering and surface analysis
Authors: Dearnaley G.
Published: February 2003

The compressive stress gradients induced by relatively energetic ion bombardment in sputtering, for surface analysis and cleaning, are shown to result in the possibility of atom migration and compositional changes. A solution to these problems is proposed.
Isotope separation by radiation pressure of coherent π pulses
Authors: Friedmann H. , Wilson A. D.
Published: February 2003

Limitations of existing methods of isotope separation, using atomic beam deflection induced by radiation pressure, are discussed. A new method, based on selective momentum transfer by intense unchirped reflected laser pulses, is proposed. The pulses produce population inversion in one isotope leaving the other unaffected. This population inversion is obtained using isotope selective optical precession. The method is supported by the full solution of the equations of motion of a two-level atom interacting with realistic light pulses of arbitrary strength.
Evaluation of dark-current nonuniformity in a charge-coupled device
Authors: Tanikawa K. , Ito Y. , Sei H.
Published: February 2003

This letter investigates the relationship between stacking faults (SF’s) and dark-current nonuniformity in a charge-coupled device (CCD) through the measurements of cell-to-cell dark-current distribution, leakage current, C-t characteristics, and the Sirtl etching of the device. It is revealed that stacking faults are strongly connected with the nonuniformity in the dark current and are the dominant origin of the dark-current spikes.
Surface ionization negative ion source
Authors: Rachidi I. , Monte J. , Pelletier J. , Pomot C. , Rinchet F.
Published: February 2003

A negative ion source that utilizes a porous lanthanum hexaboride surface to generate iodine ions is described. Iodine vapor supplied to the back of the lanthanum hexaboride ionizer from a reservoir percolates through to the front surface where the iodine is evaporated as ions. The peak ion current obtained—2.1 mA at an ion energy of 0.3 keV—leads to a density n≃1010 cm−3.
Experimental method of determining the intrinsic diffraction efficiency of holograms stored by the photorefractive effect
Authors: Moharam M. G. , Cornish W. D. , Young L.
Published: February 2003

A method is described in which a normally incident ancillary light beam of different wavelength from that used to write the holograms allows the intrinsic diffraction efficiency of holograms stored in ’’photorefractive’’ materials such as lithium niobate to be determined without error due to multiple internal reflections.
Unstable propagation of a Gaussian laser beam in a plasma waveguide
Authors: Feit M. D. , Maiden D. E.
Published: February 2003

Laser heating of long magnetically confined plasma columns to fusion temperatures requires propagation of a trapped laser beam over considerable distances. The present paper employs the parabolic approximation to the wave equation to analyze the propagation of a Gaussian beam through a plasma with a parabolic transverse density profile. Although propagation is stable in the axially uniform case, exhibiting alternate focusing and defocusing of the beam, it is unstable to small axial perturbations of certain wavelengths. In particular, an exponentially growing beam radius results from perturbations at wavelengths near that associated with the alternate focusing and defocusing mentioned above.
Optically pumped 16-μm CO2 laser
Authors: Osgood R. M.
Published: February 2003

A potentially useful 16-μm CO2 laser, oscillating on the [10°0,02°0]II to 0110 transition, is described. The v=1→v=0 lines from an HBr chemical laser were used to pump a low-pressure mixture of HBr and CO2 gases. Vibrational energy transfer from HBr followed by a 9.6-μm stimulating pulse populated the CO2 [10°0,02°0]II level.
Ultraviolet emission from CO2+ produced in low-energy He2+-CO2 collisions
Authors: Bearman G. H. , Harris H. H. , Leventhal J. J.
Published: February 2003

Cross sections for production of electronically excited states of CO2+ in low-energy He2+-CO2 collisions have been measured. The magnitudes of these cross sections are large enough to suggest the possibility of producing laser action at one or more wavelengths in an e-beam-initiated discharge in He-CO2 mixtures.
Rapid turn-off in triode optical gate liquid crystal devices
Authors: Channin D. J. , Carlson D. E.
Published: February 2003

A liquid crystal field-effect light valve with high-speed turn-off operation is described. The three-terminal device is symmetric in its turn-on/turn-off operation and uses digital rather than multifrequency addressing.
Antenna properties and operation of metal-barrier-metal devices in the infrared and visible regions
Authors: Wang Shyh
Published: February 2003

We apply the theory of linear antennas to metal-barrier-metal (MBM) devices. An expression is derived for the optical voltage induced across the insulating barrier, taking into account that the metal conductivity is in the relaxation region for infrared and visible radiation. It is shown that the optical voltage should drop with frequency according to ω−3. This ω−3 dependence suggests that we should look for new mechanisms in order to extend the usefulness of MBM devices into the visible region.
Two-species flow in relativistic diodes near the critical field for magnetic insulation
Authors: Bergeron Kenneth D.
Published: February 2003

An analysis of space-charge-limited counterstreaming flow of ions and electrons in a high-voltage planar diode in the presence of a strong transverse magnetic field is presented. A two-component one-dimensional cold-fluid model is used which includes most self-consistent effects. A substantial enhancement of ion current by a factor of 3–6 is found at fields slightly larger than the critical magnetic insulation field.
Conditions for the self-destruction of a pulsed intense relativistic electron beam
Authors: Friedman M. , Siambis J. G. , Bacon D. P.
Published: February 2003

It has been found that the stable flow of a magnetically focused unneutralized intense relativistic electron beam (IREB) depends on beam front parameters (e.g., current and voltage rise times) and on the geometry of the propagation region (e.g., length). It is argued in this letter that a pulsed IREB is susceptible to a two-stream instability resulting from reflection of electrons from the beam front. This effect may have to be taken into account in IREB applications involving fast rise times and/or long drift lengths, such as ion accelerators, electron autoaccelerators, and intense microwave generators.
Measurements of wavelength dependence of group delay in a multimode silica fiber
Authors: Ozeki Takeshi , Watanabe A.
Published: February 2003

The wavelength dependence of the group delay in a multimode silica fiber was determined from the wavelength-dependent phase shift of the sinusoidally modulated light transmitted by the fiber. When the lower-order modes were dominant in the modal power distribution, the measured dispersion at a wavelength of 830 nm was 0.90 ns/10 nm/km. When the launching conditions were changed to excite more of the higher-order modes, the measured dispersion decreased to 0.60 ns/10 nm/km, indicating that the material dispersion was compensated partially by the waveguide dispersion.
Yields of N2(C) from Ar*+N2 and XeBr* from Xe*+Br2
Authors: Searles S. K. , Hart G. A.
Published: February 2003

Investigation of reactions I and II, where * represents a low-lying electronically excited state, Ar*+N2→N2(C)+Ar (reaction I) and Xe*+Br2→XeBr*+Br (reaction II), was carried out by e-beam excitation of Ar-N2 mixtures and Xe-Cr2 mixtures. Analysis of the fluorescence data and e-beam energy deposition led to yields of 0.20 N2(C) for Ar* and 0.30 XeBr* for Xe*.
Photolytic pumping of the iodine laser by XeBr
Authors: Swingle J. C. , Turner C. E. , Murray J. R. , George E. V. , Krupke W. F.
Published: February 2003

The efficiency for producing fluorescence from the 220–340-nm bands of XeBr has been measured to be 11±5% in an electron-beam-driven device, a value consistent with an assumed kinetic model. The photolytic pumping of the 1.315-μm atomic iodine laser is demonstrated using this narrow-band fluorescer.
Normalization technique for accurate measurements of two-photon absorption coefficients
Authors: Lotem Haim , Bechtel J. H. , Smith W. L.
Published: February 2003

A new technique for accurate measurement of the two-photon absorption (TPA) coefficient relative to the known TPA coefficient of a reference material is presented. It is shown that the ratio between the transmitted energies of two identical laser pulses through the unknown and the reference materials is a constant which is independent of the laser intensity if a filter of an appropriate transmission value F is put in front of the reference material. The ratio between the two TPA coefficients is simply related to F. Using the outlined technique the ratios between the TPA coefficients of three semiconductor samples were measured with an accuracy of ±10%
Enrichment of N15 by chemical reactions in a glow discharge at 77 °K
Authors: Manuccia T. J. , Clark M. D.
Published: February 2003

We have observed enrichments of N15 as large as 21±1% in the mixed nitrogenous products (NO, N2O, NO2) of the reaction of N2 and O2 driven by a pulsed glow discharge at 77 °K. A typical energy expenditure per atom separated was 0.22 MeV. Enrichments increased but yields decreased as the electrical energy deposited per reactant molecule was reduced. Under similar conditions enrichment of 15% was observed for N15 from the reaction N2+3D2→2ND3.
Subresolution imaging: Use of wavelength and angular diversity techniques
Authors: Jain Atul
Published: February 2003

We calculate the Fourier transform of the electric field at a point on the image of an object as the angle or wavelength of the illumination on the object is varied and show that this function provides a direct measurement of the amplitude and surface height structure of the object within the resolution cell centered at the corresponding point on the object.
Velocity-field relationship of InAs-InP alloys including the effects of alloy scattering
Authors: Hauser J. R. , Littlejohn M. A. , Glisson T. H.
Published: February 2003

The drift velocity–electric field relationship for the ternary alloy InAs1−xPx has been studied by the Monte Carlo methd. Random potential alloy scattering has been included in the calculations, along with polar optical scattering, intervalley scattering, acoustic scattering, piezoelectric scattering, and ionized impurity scattering. The low-field electron mobility has also been calculated throughout the compositional range for the alloy.
First-order interaction force between a dislocation loop and flux line lattice in a type-II superconductor
Authors: Pande C. S.
Published: February 2003

Exact analytical expressions are obtained for the elementary first-order (ΔV) interaction force between a dislocation loop and flux line lattice in a type-II superconductor, using the stress field of the flux line lattice. The interaction force initially increases as the square of loop radius R, but as R is increased further it has the periodicity of a Bessel function of first order, i.e., J1.
Thermal modification of the kinetic sequence pumping the helium-nitrogen charge-transfer laser
Authors: Collins C. B. , Carroll J. M. , Lee F. W. , Cunningham A. J.
Published: February 2003

An increased output energy of 5 J/l at 427.8 nm has been obtained with 3.2% efficiency from the helium-nitrogen charge-transfer laser through the thermal modification of the kinetic sequence pumping the inversion. A decrease in gas temperature of 40 °C has been sufficient to increase output pulse energies by a factor of 2 for high currents of the electron beam discharge and by as much as a factor of 20 at lower currents. These results have necessitated a revision of the pumping sequence to include charge transfer from the ion aggregate, He+3. The new kinetic model is sufficient to predict the effects of thermal modification, as well as the strong nonlinear dependence of laser output on pressure which had been previously reported. It indicates that the theoretical limit on efficiency 6.10% May mest of 6–10% may best be approached through proper choice of the gas temperature.
High power uv noble-gas-halide laserf
Authors: Hoffman J. M. , Hays A. K. , Tisone G. C.
Published: February 2003

Using an axial electron-beam excitation scheme to excite mixture of argon, krypton, and fluorine, 108 J of laser energy, corresponding to a peak power of 1.9×109 W, was obtained from KrF at 2484 Å. In addition, ArF was observed to lase at 1933 Å with a maximum energy output of 92 J, corresponding to a power of 1.7×109 W. The maximum energy for KrF was obtained with total gas pressures of 1400 Torr using 4 Torr of fluorine and partial pressures of krypton greater than 100 Torr. When the partial pressure of krypton was less than 100 Torr both ArF and KrF were observed to laser simultaneously.
Atmospheric water vapor measurements with an infrared (10-μm) differential-absorption lidar system
Authors: Murray E. R. , Hake R. D. , van der Laan J. E. , Hawley J. G.
Published: February 2003

We report the recent design, construction, and operation of the first infrared differential-absorption lidar system for remote range-resolved sensing of gaseous species. The target gas in the present case was water vapor, which was measured using several CO2 laser lines near 10.3 μm. Profiling of the concentration of many air pollutants to a horizontal range of at least 12 km appears feasible with commercially available components.
Epitaxial deposition of infrared active devices on an insulating substrate
Authors: Lopez-Otero A. , Haas L. D. , Jantsch W. , Lischka K.
Published: February 2003

The deposition of PbTe p-n junctions on BaF2 substrates using the hot wall technique of epitaxial growth is described. Our preliminary results indicate that this method of growth could serve as a very simple alternative to more elaborate methods for the fabrication of semiconductor devices and could help in the realization of infrared integrated optical circuits and imaging devices based on IV`VI materials deposited on insulating substrates.
An InP MIS diode
Authors: Lile D. L. , Collins D. A.
Published: February 2003

Wet chemical anodic oxidation of InP in a 1% by weight solution of sodium salicylate in ethyl alcohol is shown to result in the growth of a high-quality dielectric layer. Resistivities in excess of 1013 Ω cm at room temperature have been realized with breakdown fields ∼106 V/cm. Apparent surface state densities as determined from 1-MHz capacitance-voltage plots are in the range 3–4×1011 cm−2 eV−1 over a large portion of the band gap.
Chemical bonding and high T
c in ’’Nb3Ge’’ sputtered films
Authors: Rogowski Donald A. , Roy Rustum
Published: February 2003

Soft x-ray L-emission spectra for Nb and Ge in a series of single-phase ’’Nb3Ge’’ sputtered films of known composition have been obtained. Correlations are shown to exist between Tc and the nature of the bonding as evidenced by shifts in the emission peaks of characteristic x rays. The Nb and Ge L-emission peaks shift toward lower energies with decreasing lattice parameter and Nb/Ge ratio (and increasing Tc).
New evaporation method of high-melting-temperature materials utilizing a vacuum discharge
Authors: Igarashi Yuichiro , Kanayama Michio
Published: February 2003

By utilizing a discharge caused between electrodes (specimens) in a high vacuum (≃2×10−5 Torr) and without inert gas, the evaporation of high-melting-temperature materials (W, Ta, and C) has been successfully achieved. The main part of the instrument was composed of two electrodes (0.8–1.5 mmφ) and a helical filament (0.8–1 mmφ, 10 turns). An alternating voltage was supplied between electrodes (sparking gap: 0.5–2 mm), and in order to get sparking easily, the electrodes were preheated by bombarding with electrons (emission: 500 μA) from the filament. After starting, the high voltage was lowered to a range of 1–2 kV and the filament fell in disuse. Then the discharge was maintained stably. The structure of 600-Å-thick W films deposited by this method was mostly of the ordered W3W.
Drawing-induced defect centers in a fused silica core fiber
Authors: Friebele E. J. , Sigel G. H. , Griscom D. L.
Published: February 2003

The process of fiber drawing has been found to produce defect centers in optical fibers with a silica core of low OH content (Suprasil W-1), but not in fibers with a silica core of high OH content (Suprasil 1). At least one center gives rise to the drawing-induced optical absorption, which is identical to the 630-nm band created by ionizing radiation in bulk samples of Suprasil W-1. By means of electron-spin-resonance techniques, additional drawing-induced defect centers have been observed; these centers are identical to the radiation-induced oxygen-associated hole centers in bulk fused silica.
Fast-discharge-initiated KrF laser
Authors: Sutton D. G. , Suchard S. N. , Gibb O. L. , Wang C. P.
Published: February 2003

Intense laser emission has been observed from the KrF molecule formed by a chemical reaction initiated by a fast discharge. With a gas mixture of He:Kr:NF3=500:50:1 and a sample pressure of 700 Torr, an output energy of 0.8 mJ was measured from a 25-nsec laser pulse (FWHM). Spectral analysis of the laser emission indicated laser action at 248.5 and 249.5 nm.
Optical directional coupler using tapered sections in multimode fibers
Authors: Ozeki Takeshi , Kawasaki B. S.
Published: February 2003

An optical directional coupler with high efficiency has been fabricated using tapered sections in multimode fibers. In the biconical taper sections of the coupler, some of the higher-order modes are converted into radiation modes launched into a clear adhesive and subsequently reconverted into guided modes of two arms of the coupler. The insertion loss, power coupling, and directivity were measured to be 1.0, 10.2, and 20 dB, respectively.
Improved dc dynamic scattering with redox dopants in ester liquid crystals
Authors: Lim Hong Sup , Margerum J. David
Published: February 2003

Redox dopants are used to improve the dc dynamic scattering (DS) characteristics of phenyl benzoate liquid crystals as compared to the use of salt-type conductive dopants. The redox dopants are selected by their electrochemical properties so that they react preferentially and reversibly at the electrodes, thus providing the current carriers for the dc-DS effect. Low-threshold voltages (∼2 V), high scattering efficiency (99% at 20 V), and long dc-DS lifetimes (up to 18 000 h) are obtained with an ester liquid crystal containing a redox dopant pair consisting of di-n-butyl-ferrocene and (2,4,7-trinitro-9-fluorenylidene) malononitrile.
Effects of electrically inactive ion implantation in GaAs1−xPx (x≃0.38) on photoluminescence intensity
Authors: Okabayashi H.
Published: February 2003

The effects of electrically inactive ion implantation in n-type GaAs1−xPx (x≃0.38) on photoluminescence intensity have been studied. Improvement of the photoluminescence efficiency for the near-band-gap transition was achieved by a group-III element (B and Ga) ion implantation at 1013 cm−2. Group-V element (As) ion implantation led to deterioration of the efficiency to the same degree or more than group-VIII element (Ar) ion implantation. The results suggest that the efficiency improvement is attributed to a decrease in the concentration of the ’’killer’’ center, probably associated with the Ga vacancy included in the as-grown GaAsP crystals.
Improved cw laser penetration of solids using a superimposed pulsed laser
Authors: Robin James E. , Nordin Paul
Published: February 2003

The enhancement of cw laser melt-through of solids resulting from melt removal produced by a blowoff impulse generated by short superimposed laser pulses is investigated. A simple model is used to develop an expression for the minimum impulse criteria.
Deuterium separation in formaldehyde by an intense pulsed CO2 laser
Authors: Koren G. , Oppenheim U. P. , Tal D. , Okon M. , Weil R.
Published: February 2003

The first CO2 laser enrichment of deuterium in the gaseous phase of formaldehyde is reported. Irradition with pulses from a ∼20-MW CO2 TEA laser focused strongly onto the sample yields highly efficient selective photodissociation of the formaldehyde molecule. A deuterium enrichment factor of approximately 40 is found for formaldehyde gas at an initial pressure of 20 Torr, after irradiation with 300 laser pulses.
Vapor-grown cw room-temperature GaAs/InyGa1−yP lasers
Authors: Nuese C. J. , Olsen G. H. , Ettenberg M.
Published: February 2003

Vapor-grown double-heterojunction (DH) laser structures of GaAs/InyGa1−yP have been prepared with room-temperature threshold current densities as low as 1140 A/cm2 and differential quantum efficiencies as high as 47%. cw operation at room temperature has been obtained from such devices.
GaAs p+n−n+ directional-coupler switch
Authors: Leonberger F. J. , Donnelly J. P. , Bozler C. O.
Published: February 2003

GaAs p+n−n+ electro-optic directional-coupler switches have been successfully fabricated and evaluated at 1.06 μm for use as components in integrated optical circuits. The devices were fabricated from a pair of closely spaced low-loss [α≈1 cm−1 (4.3 dB/cm) at 1.06 μm] single-mode p+n−n+ channel-stop strip guides. They are operable both as passive directional couplers and as electro-optic switches. The couplers have exhibited 98% power transfer and have an attenuation only about 0.1 dB/cm greater than that of a single guide having the same dimensions as one of the coupled guides. The switch performance was found to depend on the crystallographic direction chosen for light propagation. All devices were in the {100} plane, and 17-dB (98%) power isolation in both the switched and unswitched states with constant total power output (≲0.2-dB variation) was achieved for propagation along a [011] direction. These switches were 7.2 mm long, and had an optimum switching voltage of 43 V and a calculated power-bandwidth ratio in a 50-Ω system of 110 mW/MHz.
Multimode optical channel waveguides induced in glass by laser heating
Authors: Chen D. , Koepke B. , Zook J. D. , BernaL G. E.
Published: February 2003

Multimode optical channel waveguides are produced on filter glass wafers using a scanning focussed Ar laser beam. The localized refractive index change produced by the laser heating is measured and analyzed. The waveguide cross-sectional area is related to the laser power and scanning speed. Potential applications of this technique of channel waveguide fabrication are presented.
Fast transient spectroscopy of the free-carrier plasma edge in Ge
Authors: Jamison S. A. , Nurmikko A. V. , Gerritsen H. J.
Published: February 2003

The free-carrier plasma edge and plasma diffusion dynamics have been studied in Ge by monitoring rapid temporal variations of surface reflectivity at 10.6-μm wavelength which occur after excitation by intense picosecond pulses at 1.6 μm. The results of such transient spectroscopy show that the method can be used as a sensitive diagnostic tool for the many semiconductor plasmas.
High-energy electron gun with gas amplification of the filament current
Authors: Tulip J. , Seguin H.
Published: February 2003

A high-energy electron beam is generated using gas-ionizing collisions to amplify a small cathode filament current. The technique makes use of a crossed magnetic and electric field to reduce the effective mean free path of electrons at the cathode. At a pressure of 5×10−5 Torr helium, for example, a filament current of 0.4 mA will produce a uniform beam of 100 mA. Accelerating voltages up to 100 kV are used.
Laser generation from 6 to 35 μm following two-photon excitation of ammonia
Authors: Jacobs Ralph R. , Prosnitz D. , Bischel William K. , Rhodes Charles K.
Published: February 2003

Laser action has been observed for the first time in ammonia subsequent to two-photon absorption. Oscillation has been demonstrated in 14NH3 following two-photon excitation by a pair of CO2 TEA lasers operating on the P (34) and P (18) lines in the 10.4-μm band, respectively. The observed wavelengths are 6.27, 6.69, 12.11, 13.72, 15.88, 15.95, 18.92, 19.55, 26.10, and 35.50 μm. Identification with existing spectroscopic information indicates that eight of the laser transitions occur within the ν2 manifold and originate by radiative pathways from the 2ν2−(5,4) level at 2115.88 cm−1, whereas the remaining two, at 6.27 and 6.69 μm, take place in the ν4 mode. The usefulness of employing such lasers as sensitive probes for molecular collisional processes in excited vibrational levels is indicated.
Four-wave sum mixing (130–180 nm) in molecular vapors
Authors: Innes K. K. , Stoicheff B. P. , Wallace Stephen C.
Published: February 2003

It is demonstrated that molecular vapors such as nitric oxide, bromine, and benzene can be used for resonantly enhanced four-wave mixing into the vacuum ultraviolet. Coherent radiation in the 130–152-nm region has been generated in nitric oxide, and continuous wavelength tunability achieved by pressure broadening the rotational structure at 10 atm. Estimates of the third-order nonlinear susceptibility are shown to be consistent with the observed conversion efficiency in nitric oxide.
Dye laser action in a liquid crystal
Authors: Kuroda S. , Kubota K.
Published: February 2003

Laser oscillation of dyes in a liquid crystal was studied. The threshold power required for laser emission decreased abruptly at the phase transition temperature of the liquid crystal. Some applications of this effect are discussed.
Molecular beam epitaxial GaAs layers for MESFET’s
Authors: Wood C. E. C.
Published: February 2003

Tin-doped GaAs layers on semi-insulating substrates have been grown by molecular beam epitaxy and made into field effect transistor devices by two different technologies. Best devices gave 5.6 dB gain with associated minimum noise of 3.3 dB at 10 GHz and showed no signs of hysteresis even without a buffer layer to reduce interface state densities.
Impurity gettering in semi-insulating gallium arsenide using ion-implantation damage
Authors: Bozler C. O. , Donnelly J. P. , Lindley W. T. , Reynolds R. A.
Published: February 2003

Ion-implantation damage has been used to getter impurities from semi-insulating gallium arsenide. The gettered impurities are fast diffusers which move into the damaged layer during an anneal at 750 °C. Impurity profiles of epitaxial layers grown on the gettered surfaces after removal of the damaged material were used to evaluate the effectiveness of the gettering. The out-diffusion of compensating impurities or defects from the substrate into the epitaxial layer during growth was greatly reduced by the ion-implantation damage gettering. The same gettering effect was produced when either Ne+ or Si+ was used to create the damaged layer.
Defect spatial distributions in annealed ion-implanted silicon measured by a transient capacitance technique
Authors: Wang K. L.
Published: February 2003

Defect spatial distributions of extremely low concentration were measured, for the first time, by a transient capacitance technique in ion-implanted MOSFET’s. Aluminum gate FET’s were ion implanted through the gate oxide with 1×1012 of 28Si+ ions/cm2 at 310 keV. The devices were annealed at 650 °C before Al was put down. Energy levels for the residual defects after annealing were obtained at Ec−0.29, Ec−0.45, Ec−0.54, and Ev+0.52 eV, respectively. Then the in-depth distribution for each level was measured to a concentration of 1012/cm3 by varying the gate voltage. The profile of defect distribution shows that the annealing after low-dose implantation differs from the regrowth of the amorphous layer caused by heavy implantation and that most of the residual defects remain in the bulk rather than at the interface.
Laser oscillation involving nitrogen isoelectronic impurities in indirect-gap AlxGa1−xAs (x=0.46, 2 °K)
Authors: Gonda Shun-ichi , Makita Yunosuke , Ijuin Hachiro
Published: February 2003

Using the optical pumping method, laser oscillation was successfully achieved at 2 °K in indirect-gap AlxGa1−xAs (x=0.46) implanted with nitrogen atoms for the first time. This shows that nitrogen isoelectronic traps in AlxGa1−xAs are effective for stimulated emission and laser oscillation, particularly in indirect material.
Production processes for excited states of Cd+ in helium-cadmium afterglows
Authors: Kamin M. , Chanin L. M.
Published: February 2003

A preliminary mass spectroscopic investigation of helium-cadmium afterglows indicates that excited cadmium ions are produced by Penning and charge exchange reactions involving excited species of both atomic and molecular helium. Relative values of the reaction rate constants are presented showing those for the molecular particle processes to be the largest.
Monolithic mosaic transducer utilizing trapped energy modes
Authors: Tiersten H. F. , McDonald J. F. , Das P. K.
Published: February 2003

A transducer array consisting of a large number of separated sets of electrodes plated on a single piezoelectric plate of uniform thickness is described. Each set of electrodes is made to act essentially independently by placing them sufficiently far apart and employing an essentially trapped energy mode. Experimental results obtained with a linear array on PZT-7A show that the isolation is very good over a bandwidth of about 14%, close to the calculated bandwidth of 12.8%.
Independent fourth-order elastic coefficients for quartz
Authors: Markenscoff Xanthippi
Published: February 2003

The eighth-order tensors invariant under the transformations corresponding to the point groups 32, 3m, and 3̄m (trigonal system) are obtained and the list of the independent fourth-order elastic coefficients is presented.
Shift and broadening of saturated absorption resonances due to curvature of the laser wave fronts
Authors: Hall J. L. , Bordé C. J.
Published: February 2003

Using frequency offset-locked spectroscopy of methane at 3.39 μm we show that the saturated absorption peaks can be significantly blue or red shifted if the wave fronts of the laser beam are spherical in the gas cell. Good agreement with theoretical prediction is found. We discuss suitable conditions to avoid this geometry-induced shift in optical frequency standards.
100-ps pulse generation and amplification in the iodine laser
Authors: Fill E. , Hohla K. , Schappert G. T. , Volk R.
Published: February 2003

We have generated 100–200-ps iodine 1.315-μ laser pulses by means of the free induction decay (FID) technique. A 2.5-ns switched-out pulse from a mode-locked oscillator is truncated by generating its own gas breakdown in the focal spot between two lenses and then passed through a hot I2 absorber operated in the small-signal regime to generate a short FID pulse. Streak camera studies of such pulses showed that the breakdown time was about 40 ps and the FID pulses had a full width at half-maximum of about 100–200 ps. Subsequent amplification of a pulse showed that the 4-GHz bandwidth of the atmospheric pressure iodine amplifier was insufficient to cover the pulse spectrum. A calculation of the pulse width based on the reduction of the small-signal gain due to such spectral considerations also gave pulse widths in the 100–200-ps range.
cw room-temperature InxGa1−xAs/InyGa1−yP 1.06-μm lasers
Authors: Nuese C. J. , Olsen G. H. , Ettenberg M. , Gannon J. J. , Zamerowski T. J.
Published: February 2003

Room-temperature cw laser operation at wavelengths between 1.06 and 1.12 μm has been obtained from double-heterojunction structures of InxGa1−xAs/InyGa1−yP prepared by vapor-phase epitaxy. These devices have pulsed threshold current densities as low as 1000 A/cm2 and external differential quantum efficiencies as high as 55%. Their active laser cavities are between 0.14 and 0.36 μm thick, providing fundamental transverse-mode operation with far-field patterns 50 to 60° wide.
(110) bubble garnet films with growth-induced orthorhombic anisotropy
Authors: Wolfe R. , LeCraw R. C. , Blank S. L. , Pierce R. D.
Published: February 2003

Garnet films of compositions (EuLaCa)3 (FeGeAl)5O12 which support magnetic bubbles have been grown by liquid phase epitaxy on (110), (111), and (100) substrates of Nd3Ga5O12. In each material, La plus Eu provides the growth-induced uniaxial anisotropy in (100) films, Ca plus Eu in (111) films, and the combination provides a normal easy axis as well as in-plane anisotropy in (110) films. General conditions for achieving stable bubbles and large in-plane anisotropy in (110) films are discussed in terms of the phenomenological theory of growth-induced plus stress-induced anisotropy.
Determination of minority-carrier diffusion length in indium phosphide by surface photovoltage measurement
Authors: Li Sheng S.
Published: February 2003

The surface photovoltage technique has been employed to measure the hole diffusion length on three n-type InP specimens. The hole diffusion length was found to be 1.8 μm for specimens with (111) orientation and 1.4 μm for specimens with (100) orientation. The measured hole diffusion length was found to be independent of the surface conditions.
Surface acoustic wave electromagnetic transducers from multiconductor flat cable
Authors: Frost H. M. , Szabo T. L.
Published: February 2003

We describe a new method for making meander-line surface acoustic wave electromagnetic transducers at megahertz frequencies from multiconductor flat cable. Commerically available cable, consisting of uniform patterns of rectangular conductors, is used to fabricate identical transducers with well-characterized electrical and acoustical properties. Also new expressions for the electrical inductance and transduction efficiency of these transducers are presented and compared to measurement for several Rayleigh wave devices. Measured transducer bandwidths agree with a predicted (sinX/X)2 response. Unique features of cable transducers are exploited in novel designs and applications such as precise velocity measurement and crack detection on curved surfaces.
Acoustic surface wave interaction charge-coupled device
Authors: Gaalema Stephen D. , Schwartz Richard J. , Gunshor Robert L.
Published: February 2003

The observation of the synchronous drag of minority carriers by the electric field associated with an acoustic surface wave is reported. This phenomenon is exploited in a new charge-coupled device (CCD) which uses a traveling piezoelectric surface acoustic wave in place of the gate structure of a conventional CCD. The surface wave interaction CCD (SWICC) should have several potential advantages over normal CCD’s, including increased information density, higher speed, and lower power consumption.
Source emission and photoelectron production in a seeded CO2 laser mixture
Authors: Seguin H. J. J. , McKen D. , Tulip J.
Published: February 2003

Measurements of spark source emission, transmission, and photoionization spectra in a CO2 laser mixture seeded with a low-ionization-threshold additive are presented. The results show a photoelectron density enhancement in excess of 3 orders of magnitude contained within a narrow transmission band at 1200 Å. Enhancement is also observed at wavelengths between 1700 and 2100 Å. The long-wavelength effect, characterized by an increased photon mean free path, may identify a two-step photoionization process.
Multistrip coupling to SAW resonators
Authors: Li R. C. M. , Alusow J. A.
Published: February 2003

The behavior of a multistrip coupler in a standing-wave environment has been investigated with the use of a SAW resonator, both theoretically and experimentally. An understanding of this behavior is important to the design of multistrip coupled-resonator filters.
Radiative transitions of photoexcited electrons between Landau levels in n-InSb
Authors: Gornik E. , Nguyen V. T. , Damen T. C.
Published: February 2003

We report the first observation of radiation corresponding to transitions of photoexcited electrons between the two lowest Landau levels in n-InSb at 2 K. These excited electrons are produced by irradiating a high-purity n-InSb sample (n=2×1013 cm−3) with a 10.6-μm CO2 laser beam. From the study of the radiated power we determine an excited electron density of about 6×1012 cm−3 for an emission frequency of 100 cm−1 and a pump intensity of 2×106 W cm−2.
Effect of gas-phase stoichiometry on the minority-carrier diffusion length in vapor-grown GaAs
Authors: Ettenberg M. , Olsen G. H. , Nuese C. J.
Published: February 2003

The electron diffusion length in Zn-doped (p ∼1×1019 cm−3) vapor-grown GaAs has been found to depend strongly on the gas-phase stoichiometry used during epitaxial deposition. Specifically, near-stoichiometric or Ga-rich flow conditions provide diffusion lengths as large as 4.8 μm; this is about a factor of two larger than that of VPE GaAs prepared under commonly used As-rich flow conditions, and is comparable to that of LPE GaAs. Furthermore, the modified gas-flow conditions provide reduced threshold current densities for a room-temperature double-heterojunction laser of GaAs/In0.5Ga0.5P.
Bandwidth-limited subpicosecond pulse generation in mode-locked cw dye lasers
Authors: Ruddock I. S. , Bradley D. J.
Published: February 2003

A cw Rhodamine 6G dye laser with a thin optically contacted saturable absorber cell has been mode locked over an operating frequency range of 598–615 nm to produce pulses with durations as short as 0.3 ps. The pulses, with sech2 intensity profiles, are practically bandwidth limited.
Solution growth of metallopolymer films
Authors: Chopra K. L. , Rao T. V. , Rastogi A. C. , Barthwal S. K.
Published: February 2003

A solution growth technique has been developed to obtain polymer films doped with high concentrations (up to 18% by weight of polymer) of metals such as Cu, Co, Ni, and Fe. Electron microscopy, EPR, and optical studies of Cu-doped polyvinylchloride films show the existence of homogeneously distributed copper in colloidal, Cu+, and Cu2+ states.
Shock wave introduction of gas into relativistic e-beam-pumped lasers and drift tubes
Authors: Dreyfus R. W.
Published: February 2003

The pressure differential across a shock wave provides the low pressure required to launch an electron beam from a field-emission cathode and the high pressure needed for electron-beam-pumped gas lasers. This new pumping arrangement has eliminated the conventionally employed fragile anode foil, which causes scattering of the electron beam and which limits energy density and repetition rate. Initial results indicate that longitudinally pumped gas lasers have output powers an order of magnitude greater than that attained with the anode foil.
Modified absorption method to determine level population densities in a cataphoresis type of He-metal laser discharge
Authors: Goto T. , Mori M. , Hattori S.
Published: February 2003

A method was developed with which we could easily obtain exact absorption coefficients not only of visible lines but also of ultraviolet lines to determine atom or ion densities in energy levels in a cataphoresis type of positive column gas discharge. This method was applied to a typical He-metal laser, He-Cd+ laser, and it has been confirmed that the method gives an accurate value of the Cd+ ion density in the Cd(II) ground level 5s2S1/2.