bluuebunny/crossref_metadata_2025 huggingface dataset:
Holographic recording in thermoplastic at 1.15 μm
Authors: Colburn W. S. , Ralston L. M. , Dwyer J. C.
Published: January 2004

Holograms have been recorded on an photoconductor-thermoplastic device at 1.15 μm. Diffraction efficiencies of 1–5% were obtained with exposures of 400–800 mJ/cm2. Holograms were formed in situ with rapid processing and at spatial frequencies as high as 1000 lines/mm.
Strain-induced degradation of GaAs injection lasers
Authors: Hartman R. L. , Hartman A. R.
Published: January 2004

This letter shows that strain is a controlling factor in the rapid degradation of GaAs double-heterostructure junction lasers. A birefringence study of these lasers reveals extensive strain fields introduced during the bonding procedure resulting from the different thermal-expansion coefficients of the materials involved. A new bonding procedure was developed which does not introduce significant strains. Lasers fabricated with the old and new bonding procedures were subjectively categorized as low, moderate, or high strained. A direct correlation was measured between low-strain and room-temperature cw laser lifetime. Lasers fabricated with the new bonding procedure have operated cw for as long as 880 h.
Frequency locking of a cw dye laser near atomic absorption lines in a gas discharge
Authors: Shank C. V. , Klein M. B.
Published: January 2004

Frequency locking of the cw dye laser to atomic absorption lines in helium and sodium gas discharges is reported. The mechanism for locking is attributed to a lens formed by the radial variation of index of refraction in the positive column.
Fast-neutron dosimetry using F centers in MgO
Authors: Ritz Victor H. , Attix Frank H.
Published: January 2004

A fast-neutron dosimeter is described, the operation of which is based on the detection of F centers produced in MgO by displacement collisions. The F-center production rate is greatly enhanced by hydrogenous surroundings from which recoil protons are ejected. The absorbed dose is measured by means of the 350 °C exoelectron emission peak. The response is linear from 10 to 600 rad (tissue) and approximately independent of neutron energy from 2 to 15 MeV. The response to fast neutrons divided by the response to γ rays is [inverted lazy s] 0.90 on a tissue-rad basis.
Charge storage characteristics of MIS structures employing dual-insulator composites of HfO2–SiO2 and SrTiO3–SiO2
Authors: Shuskus A. J. , Quinn D. J. , Cullen D. E.
Published: January 2004

Two MIS versions have been fabricated employing rf-sputtered dual insulator structures comprised of 1000 Å HfO2-20 Å SiO2 and 1000 Å SrTiO3-20 Å SiO2. The high-dielectric-constant insulators in combination with a 20-Å layer of silicon dioxide permit the transfer of charge by tunneling into traps at the dual-insulator interface to occur at considerably lower voltages than comparable structures employing silicon nitride or aluminum oxide. It was found that trap density and, hence, the degree of flat-band voltage shift could be altered by sputtering 50-Å layers of selected materials at the insulator-SiO2 interface. The devices employing hafnium dioxide show promise in an application as a nonvolatile electrically alterable memory element. Although the strontium titanate devices exhibit a low threshold voltage for onset of charge transfer, the charge retention characteristics are poor.
Use of Mg diffusion in p-type Si to measure the residual P concentration by infrared absorption
Authors: Pajot B. , Taravella G. , Bouchaud J. P.
Published: January 2004

Two possibilities for observing the infrared absorption of residual phosphorus in p-type silicon are discussed. Experimental results show that in p-type silicon the pairing of Mg, presumably with boron and/or oxygen, produces donor complexes with ionization energy less than that of phosphorus. The integrated intensity of the phosphorus lines of the sample after Mg diffusion indicates a phosphorus concentration of ∼ 1.5 × 1013 atoms/cm3.
Degradation characteristics of cw optically pumped AlxGa1−xAs heterostructure lasers
Authors: Johnston W. D. , Miller B. I.
Published: January 2004

The characteristic formation of dark filamentary features during the rapid degradation mode of AlxGa1−xAs double-heterostructure lasers has been observed in material with no contacts, with or without a p-n junction, and in minimal-strain mounting configurations. The degradation was observed in optically pumped cw lasing and nonlasing conditions with active region temperatures near and above room temperature.
Single-line operation of a 2-W longitudinal cw CO chemical laser with no frequency-selective element in the optical cavity
Authors: Hirose Y. , Nachshon Y. , DeTemple T. A. , Coleman P. D.
Published: January 2004

An experimental condition has been found for the CO chemical laser where it would appear that vibration-vibration relaxation processes (V-V) compete with stimulated emission to force the laser to operate in essentially a single line ν = 10–9, P(17). No frequency-selective element has been used in the laser cavity. Experimental data and results of computations on a laser model are presented to support this suggestion. A cw power of 7 W has also been achieved in this longitudinal flow system with the addition of cold CO (300 °K) for the chemical efficiency of ∼ 3.2%, one of the highest values for any system reported at the present time.
Laser-induced anisotropic thermoelectric voltages in thin films
Authors: von Gutfeld R. J.
Published: January 2004

Transverse thermoelectric voltages have been observed to occur when thin Mo and W films are excited by pulsed laser light at normal incidence to the film. Wavelengths in the range 0.46–1.06 μm and pulse widths of ∼ 3–300 nsec were used. A maximum thermoelectric voltage of ∼50 mV occurring across a load resistance of 50 Ω for an ∼ 1-kW incident laser pulse has been observed. A correlation between intrinsic film stress and output voltage suggests that the stress gives rise to a nonscalar absolute thermoelectric power (Seebeck coefficients) even though the transport properties of these bulk materials are isotropic.
Auger electron spectroscopy study of oxidation on lanthanum hexaboride
Authors: Oshima C. , Kawai S.
Published: January 2004

In order to clarify the poisoning mechanism of the LaB6 cathode, the temperature dependence of oxidation on a single-crystal surface was examined by Auger electron spectroscopy. The oxidation gives the chemical effect on the La and B Auger peaks. Evidence from the Auger spectra indicates that the oxygen is more strongly bound to La ions than B ions on the surface. A correlation between the oxidation and the poisoning characteristics was established, and possible reasons for the correlation are discussed.
Angular dependence of optical scattering in mixed nematic-cholesteric liquid crystals
Authors: Oron N. , Yu J. L. , Labes M. M.
Published: January 2004

Although the wavelength of maximum scattering in cholesteric liquid crystals is strongly angularly dependent, doping with nematics can produce systems in which the angular distortion is considerably reduced, thus making color display applications much more feasible.
Laser oscillation in epitaxial GaAs waveguides with corrugation feedback
Authors: Nakamura M. , Yen H. W. , Yariv A. , Garmire E. , Somekh S. , Garvin H. L.
Published: January 2004

Laser action was observed in GaAs epitaxial films using corrugation feedback. The output wavelength was found to depend on the corrugation period. The loss, threshold gain, and feedback parameters were determined and compared with theoretical predictions.
Sputtered ferroelectric thin-film electro-optic modulator
Authors: Russo D. P. Gia , Kumar C. S.
Published: January 2004

The modulation of guided optical waves has been accomplished using an integrated ferroelectric thin-film structure. LiTaO3 was rf sputtered onto 7059 glass in an argon-oxygen environment. Electrodes for applying the modulation signal were formed by chemically etching an interdigital pattern in gold which was rf sputtered onto the LiTaO3. The observed modulation of guided waves launched in the ferroelectric film can be attributed to the linear electro-optic effect.
Two-photon absorption of Nd laser radiation in GaAs
Authors: Kleinman D. A. , Miller Robert C. , Nordland W. A.
Published: January 2004

The two-photon absorption coefficient of GaAs at 1.32 μm is found to be 0.033 ± 0.015 cm/MW. This value was obtained from transmission measurements employing a Q-switched Nd–YAG laser and an improved theoretical analysis taking into account fluctuations and the Gaussian pulse shape. Evidence of thermal self-focusing was seen in samples with linear absorption coefficients of order 1 cm−1 or larger.
Light-focusing plastic rod prepared from diallyl isophthalate-methyl methacrylate copolymerization
Authors: Ohtsuka Yasuji
Published: January 2004

We have prepared a light-focusing plastic rod, having a parabolic refractive-index distribution, from a special and simple technique of diallyl isophthalate-methyl methacrylate copolymerization. The internal transmission loss at 6328-Å wavelength is 1.0 dB/m. The period of sine curved ray path through the rod and the constant of refractive-index gradient are 50 mm and 0.0158 mm−2, respectively. The 13-mm-long 3.35-mm-diam rod functions as a lens with a 38 ° 54′ field angle.
Threshold, spectral, and output power characteristics of GaAs/Ga1−xAlxAs single-heterostructure diode lasers
Authors: Rossi J. A. , Heckscher H. , Chinn S. R.
Published: January 2004

By using an antireflection-coated GaAs diode in conjunction with a diffraction grating, we show that the diode threshold current and output power are strong functions of the lasing wavelength. The diode threshold is lowest at the longer wavelengths at which it is possible to lase the diode, but the total output power in this wavelength region is limited. The data are useful in interpreting the characteristics (spectral, threshold, and power) of a normal uncoated diode laser.
The superconductor-semiconductor Schottky barrier diode detector
Authors: McColl M. , Millea M. F. , Silver A. H.
Published: January 2004

The superconductor-semiconductor contact diode, or super-Schottky-barrier-diode, has been examined theoretically and experimentally as a video detector of high-frequency radiation. The measured noise-equivalent power (NEP) of the device is believed to be the smallest value ever reported in the literature for video detection. Moreover, the high reliability established for the ordinary Schottky barrier diode is in evidence for the proposed diode. The doping of the semiconductor is chosen large enough so that electron tunneling dominates the volt-ampere behavior of the diode. As such, for T < Tc and V < Δ, the diode exhibits a high degree of nonlinearity in its volt-ampere characteristic. It is this nonlinearity that the super-Schottky-diode exploits. Initial results with p-type GaAs at 1 °K have yielded an NEP of 2 × 10−15 W/Hz1/2 at 10 GHz.
Observation of a new domain configuration in polycrystalline FeSi films
Authors: Pockrand I. , Verweel J.
Published: January 2004

FeSi films have been rf sputtered on glass, fused silica, and Si substrates. Sputter targets of 2 and 7 wt% Si were used, and the film thickness was varied between 0.1 and 4 μm. Several films, especially those on glass in the 0.5-μm-thickness range, showed a characteristic roughly rectangular domain structure. The films were isotropic. The structure has been analyzed with the longitudinal magneto-optic Kerr effect by rotating either the film or the demagnetizing field in the film plane. The magnetization made an angle of about 18° with the longer walls. A new magnetization process, ``wall rotation'', could be observed.
A new scanning microdiffraction technique
Authors: van Oostrum K. J. , Leenhouts A. , Jore A.
Published: January 2004

It is shown that scanning display of diffraction patterns is possible with a fixed electron detector placed at the appropriate position in the final image in an electron microscope, if the direction of illumination is varied by means of deflection coils in the wobbler unit. The diameter of the specimen area selected for diffraction study can be as small as 100 Å, depending on detector dimensions and microscope magnification. This technique for microdiffraction has been demonstrated with samples of small gold particles evaporated on a collodion substrate.
Screening of metal film defects by current noise measurements
Authors: Vossen J. L.
Published: January 2004

Current noise measurements at high current densities have been applied to the detection of constrictions in thin-film metallization. Potentially open metal films due to scratches, notching, improper step coverage, etc., are easily detected. The noise level, in the absence of such defects, appears to be an indicator of potential electromigration failure. For Al films, the minimum current density to obtain sensitivity is 2 × 106 A/cm2. For more refractory metals the minimum is higher (e.g., Mo, 1 × 107 A/cm2).
Transient observations of field-induced nematic-cholesteric relaxation
Authors: Kashnow R. A. , Bigelow J. E. , Cole H. S. , Stein C. R.
Published: January 2004

We have found that the relaxation process in the electric-field-induced cholesteric-nematic transition depends upon sample boundary conditions. Homeotropic samples exhibit a delay time, followed by nucleation of the decay sequence about isolated surface defects. Transient capacitance measurements and cinemicrophotography of this process are reported for the first time.
Linewidth parameters from the Lamb dip in a cw HF chemical laser
Authors: Glaze James A.
Published: January 2004

The Lamb dip in the power spectrum of a cw HF chemical laser has been observed. The width and depth of this dip were measured as a function of the partial diluent pressure (He or N2) of the lasing mixture. From these measurements the Lorentzian linewidth parameters γHF–He and γHF–N2 for the pressure-broadened laser transitions were found to be about 4 and 18 MHz/torr, respectively.
Pumping of high-pressure CO2 laser media via a fast-burst reactor and electrical sustainer
Authors: McArthur D. A. , Miller G. H. , Tollefsrud P. B.
Published: January 2004

The Sandia Pulse Reactor (SPR II) is used to preionize an atmospheric CO2 laser medium with an applied electrical sustainer field. The small-signal gain and sustainer currents were measured for several mixtures and pressures. Small-signal gain coefficients approaching 0.04 cm−1 were measured at approximately atmospheric pressures.
cw single-line CO laser on the v = 1 → v = 0 band
Authors: Djeu N.
Published: January 2004

cw single-line laser oscillation has been achieved on the P(9), P(10), and P(11) transitions in the v = 1 → v = 0 band of CO. The observations were made on a conventional electrical discharge slow-flow device filled with a mixture of He, N2, Xe, and CO.
Comparison of theory and experiment for nanosecond-pulse amplification in high-gain CO2 amplifier systems
Authors: Stark E. E. , Reichelt W. H. , Schappert G. T. , Stratton T. F.
Published: January 2004

Short-pulse energy extraction measurements have been made on the Los Alamos Scientific Laboratory three-stage amplifier system. The energy extraction from one, two, and all three stages was found to be in excellent agreement with a rate equation theory including rotational relaxation and beam expansion. Amplified pulse energies of up to 20 J in 1.5 nsec were obtained.
Gratings for integrated optics fabricated by electron microscope
Authors: Turner J. J. , Chen B. , Yang L. , Ballantyne J. M. , Tang C. L.
Published: January 2004

The use of gratings fabricated by scanning electron microscope exposure of electron resist for applications in integrated optical devices is reported. These gratings have been successfully used to couple light into and out of thin-film optical waveguides and as masks for ion milling gratings into bulk GaAs. This suggests the possibility of using electronically controlled scanning electron microscopes to form complex miniaturized integrated optical devices with potentials not unlike those of modern integrated-electronics technology.
uv photoionization density measurements in TEA lasers
Authors: Seguin H. J. J. , Tulip J. , McKen D.
Published: January 2004

Diagnostic measurements on uv photogenerated laser plasmas are presented. Ionization data obtained with an X-band microwave interferometer show plasma density to be a function of both the gas mix and the irradiation source parameters. Electron density as a function of pressure is given for selected gases and mixtures. At atmospheric pressure the photoplasma density in the standard CO2 laser mix is found to be surprisingly low.
Method for examining solid specimens with improved resolution in the scanning electron microscope (SEM)
Authors: Wells O. C. , Broers A. N. , Bremer C. G.
Published: January 2004

We have obtained a low-loss image from a solid specimen in the high-field region of the condenser-objective lens in a high-resolution SEM. These experiments have demonstrated an edge sharpness of 15 Å and a point-to-point resolution of better than 50 Å between gold dots on a latex ball on a solid substrate. In theory, it should be possible to obtain micrographs from solid specimens with a resolution of 10 Å by this method.
New liquid-crystal method for revealing ferroelectric domains
Authors: Furuhata Y. , Toriyama K.
Published: January 2004

It was found that a layer of the nematic liquid crystal p-N-(p-Methoxybenzylidene) amino n-butylbenzen, extended on a triglycine sulfate crystal, takes on an orientational pattern which delineates the polarized domain structures. This technique quickly delineates domain structures in great detail and can be used on a wide variety of ferroelectric crystals. It is even applicable to a uniaxial regular type in which a domain structure cannot be detected by ordinary optical methods. The new method and the ordinary carbon powder pattern technique were compared on a triglycine sulfate crystal.
Cyclotron resonance breakdown with submillimeter lasers
Authors: Lax Benjamin , Cohn Daniel R.
Published: January 2004

The effect of cyclotron resonance absorption upon laser-induced gas breakdown is calculated. It is shown that the threshold power for breakdown is dramatically reduced at resonance. The calculations are carried out in the limits of both short and long laser pulses. In the short-pulse limit, the threshold power is determined by the length of laser pulse; in the long-pulse limit, it is determined by electron diffusion from the breakdown region and by energy loss resulting from elastic collisions.
Barrier determinations on Ge–AlxGa1−xAs and GaAs–AlxGa1−xAs p-n heterojunctions
Authors: Howarth D. S. , Feucht D. L.
Published: January 2004

The energy barriers for p-n Ge–AlxGa1−xAs and GaAs–AlxGa1−xAs heterojunctions have been determined by capacitance measurements. The results indicate that the valence band of AlxGa1−xAs tends to remain fixed with respect to the vacuum level for different values of x. This leads to spiked barriers in the conduction band for these junctions. The values determined for the barriers are consistent with measurements on p-p Ge–GaAs junctions.
Optically pumped 33-atm CO2 laser
Authors: Chang T. Y. , Wood O. R.
Published: January 2004

Single nanosecond laser pulses at wavelengths near 10 μm have been obtained by using a pulsed HBr laser to optically pump pure CO2 gas at pressures up to 33 atm in a 1-mm-long optical resonator. At pressures above 17 atm, the laser oscillates on the 10.3-μm R branch rather than on the usual 10.6-μm P branch.
Measurements of negative gain for Hg2 continuum radiation
Authors: Hill R. M. , Eckstrom D. J. , Lorents D. C. , Nakano H. H.
Published: January 2004

Gain measurements have been made at wavelength intervals over the continuum bands of high-pressure mercury excited by a short high-intensity electron beam pulse. These measurements, which utilized both continuum and laser light sources, showed net absorption at all wavelengths tested. This indicates that Hg2* has a larger cross section for absorption than for stimulated emission to the repulsive ground state, and virtually elminates the chances of laser action on these transitions.
Determination of vibrational and translational temperatures in gas-dynamic lasers
Authors: Avizonis P. V. , Dean D. R. , Grotbeck R.
Published: January 2004

The vibrational and rotational temperatures in the supersonic flow of a gas-dynamic laser have been determined simultaneously by using spectral gain measurement techniques (over a number of rotational lines). The vibrational and rotational temperature and, consequently, the optical energy in the flow are reported for two different gas-dynamic lasers having significantly different area ratio nozzles and varying stagnation temperatures.
Radiative lifetime in GaAs1−xPx p-n junctions
Authors: Edmonds H. D. , Smith A. W.
Published: January 2004

The radiative lifetime in GaAs1−xPx light-emitting diodes is observed to increase from 2 to 11 nsec with increasing injection level. A related increase in quantum efficiency is also observed. These observations are explained by using a trap-filling model, where the traps arise from defects in the epitaxially grown GaAs1−xPx.
Neodymium-doped silica lasers in end-pumped fiber geometry
Authors: Stone J. , Burrus C.A.
Published: January 2004

Fused SiO2 has been used as a new noncrystalline host for the fabrication of two types of neodymium-doped room-temperature lasers, one of which operates at 1.06-μm and the other at 1.08-μm wavelength. The lasers have the geometry of clad optical fibers, with active cores as small as 15-μm diameter by 1-cm length. They are end pumped at 0.590 and 0.5145 μm with a pulsed dye laser and an argon ion laser, respectively. Thresholds as low as 1–2 mW of absorbed pump power in a 40-μm-diam core have been obtained, and eventual pumping with high-radiance semiconductor optical sources appears feasible.
Low-pressure gas breakdown with CO2 laser radiation
Authors: Hacker M.P. , Cohn D.R. , Lax B.
Published: January 2004

The threshold power for CO2-laser-induced gas breakdown in helium has been studied at many pressures in the range of 50–700 Torr by using laser pulses of two different lengths. These measurements show that electron diffusion losses play an important role at these pressures. The experimental data can be quantitatively accounted for by taking into account both diffusion losses and the finite length of the laser pulse. In addition, it is found that the breakdown threshold power is significantly lowered when longer laser pulses are used and that elastic losses appear to play an important role at pressures above 500 Torr.
Light shift effects in the Rb87 maser
Authors: Busca G. , Tetu M. , Vanier J.
Published: January 2004

A theoretical analysis of the effect of the pumping light on the Rb87 maser frequency is summarized. Experimental results obtained on such a maser are given and are found to agree with the theory. A new method of tuning the maser cavity for a light-independent frequency setting (LIFS) is proposed.
Effects of gamma radiation on charge-coupled devices
Authors: Barbe D.F. , Killiany J.M. , Hughes H.L.
Published: January 2004

The effects of ionizing radiation (gamma) on the operation of two-phase stepped-oxide surface-channel charge-coupled devices (CCD's) were studied. For total doses up to 105 rad (Si), the primary cause of changes in CCD operation is a negative shift in the flat-band voltage, with the flat-band voltage shift for the polysilicon electrodes being greater than that for the aluminum electrodes. For fixed applied voltages, the flat-band voltage shifts cause (i) an increase in transfer inefficiency due to the cutoff of fat zero, and (ii) a decrease in the full-well capacity due to the modified surface potential profile. Up to 105 rad, the preirradiation transfer inefficiency could be recovered by changing the input-gate voltage to compensate for the flat-band voltage shift. Up to 105 rad, no significant effects due to radiation-induced interface states were observed; however, at 3 × 105 rad, increases in transfer inefficiency and dark current attributed to radiation-induced interface states were observed.
Optical waveguides in single layers of Ga1−xAlx As grown on GaAs substrates
Authors: Garmire E.
Published: January 2004

Efficient low-loss optical waveguides have been made with the growth of only a single epilayer of Ga1−xAlx on GaAs substrates. The AlAs concentration gradient which is grown by liquid-phase epitaxy using thin gallium melts is the cause of the guiding.
Hard optical storage through electrical sensitivity switching
Authors: Morikawa Takitaro , Nakajima Takashi , Sakurai Kenjiro
Published: January 2004

The sensitivity-switched holographic memory of Te–Ge–As amorphous semiconductor film was investigated. The sensitivity of the film can be enhanced only in writing by bias voltage switching. Holograms were easily stored with the simultaneous application of bias voltages and low-power laser beams. Coupled with optoelectronic hybrid systems, these amorphous materials are expected to be useful for laser information processing.
Electron beam concentration enhanced by a laser-produced plasma
Authors: Miller P. A. , Chang J. , Kuswa G. W.
Published: January 2004

A new technique has been developed for the production of tightly focused intense relativistic electron beams. A collimated plume of laser blowoff plasma is injected on axis into the anode-cathode gap region of a low-impedance diode prior to the beam pulse. The electron beam is found to pinch in the diode to current densities ≥ 2 MA/cm2.
Limiting currents in unneutralized relativistic electron beams
Authors: Nation J. A. , Read M.
Published: January 2004

The space-charge depression of the potential within an unneutralized relativistic electron beam limits the beam current. Calculations of this effect are presented for an annular beam and compared to experiment.
X radiation from high-energy-density exploded-wire discharges
Authors: Mosher D. , Stephanakis S. J. , Vitkovitsky I. M. , Dozier C. M. , Levine L. S. , Nagel D. J.
Published: January 2004

Exploded-wire discharges of tungsten and titanium driven by a high-power pulse generator have been used to produce intense x-ray continuum and line radiation. A calibrated LiF crystal spectrograph recorded the radiation spectrum in the 3- to 25-keV range. More than 20 J of x radiation are emitted in this photon energy band by tungsten plasmas in less than 50 nsec. The source of emission is less than 1 mm in diameter and about 3.5 cm long.
Origin of the holding current in threshold switching devices
Authors: Flora Laurence P. , Adler David
Published: January 2004

It is shown that the holding current in threshold switching devices is a consequence of the time rate of recovery of threshold voltage taken together with the device capacitance. The application of these considerations to recent double-pulse experiments is also discussed.
Hg-implanted Hg1−x Cdx Te infrared photovoltaic detectors in the 8- to 14-μm range
Authors: Fiorito G. , Gasparrini G. , Svelto F.
Published: January 2004

p-n junction photovoltaic detectors have been obtained by Hg implantation in Hg1−x Cdx Te for the 2- to 14-μm band. High-sensitivity photodiodes were achieved over the entire range quoted; the most interesting results are those concerning the 8- to 14-μm range; peak detectivity better than 1010 cm Hz1/2 W−1, a zero-bias resistance area product between 2.4–0.12 Ω cm2, spcific responsivity between 1.2 × 104 and 5 × 102 V W−1, and quantum efficiency between 65% and 45% were obtained.
Schottky barrier height of n-InxGa1−xAs diodes
Authors: Kajiyama K. , Mizushima Y. , Sakata S.
Published: January 2004

The barrier heights φB of Au/n-InxGa1−xAs diodes are measured by the capacitance-voltage and saturation current methods. The composition dependence of the barrier height is φB (eV) = 0.95 − 1.90x + 0.90x2. A low barrier height with a relatively wide band gap is obtained in this system.
Intense recombination radiation and room-temperature lasing in CdS excited by high-voltage rf current pulses
Authors: Nicoll F. H.
Published: January 2004

Intense recombination radiation has been observed in CdS crystals along certain crystallographic planes when excited by short high-voltage rf pulses applied through an electrical contact. The addition of high-reflectivity dielectric mirrors provides a Fabry-Perot cavity in which pulsed lasing occurs at room temperature. Some mechanisms are suggested for the new form of high-density excitation, and possible implications are discussed.
High-efficiency coaxial waveguide dye laser with internal excitation
Authors: Burlamacchi P. , Pratesi R.
Published: January 2004

A new configuration for flash-pumped dye lasers is presented. A coaxial dye cell with internal excitation is used and 2% efficiency is feasible. Optical cavity deterioration produced by thermally induced refractive index gradients is compensated by the coaxial geometry, and low-loss guided propagation results without any recirculation of the dye solution.
Evidence of the polar Kerr effect in magnetic thin films with head-on domains
Authors: Hsieh E. J. , Chau H. H.
Published: January 2004

A modified Kerr optical technique was used to view the polar Kerr component at the head-on domain wall of a magnetic thin film. The observation substantiated the polar magnetic configuration previously proposed and allowed a direct measurement on the width of the domain wall.
Theory of electromechanically induced acoustic phonon echoes
Authors: Fedders Peter A. , Lu Eugene Y. C.
Published: January 2004

A theory of electromechanically induced acoustic phonon echoes is presented. The predicted echo pulse height and width are found to depend on the exciting pulse widths and frequencies, in agreement with experimental observations. Interesting new experiments with much larger predicted echo effects are suggested.
Double-discharge copper vapor laser with copper chloride as a lasant
Authors: Chen C. J. , Nerheim N. M. , Russell G. R.
Published: January 2004

A copper vapor laser utilizing copper chloride as a lasant in a heated discharge tube has been studied. The lasing action was observed only when two successive discharge current pulses at suitable time intervals were applied. The first pulse is considered to be a dissociation pulse to produce copper and chlorine atoms; the second to be a pumping pulse to produce population inversion. The maximum energy density measured to date was 17 μJ/cm3.
NdLa pentaphosphate laser performance
Authors: Damen T. C. , Weber H. P. , Tofield B. C.
Published: January 2004

Laser operation is reported in a new crystalline material with high Nd content (2 × 1021 cm−3) whose concentration quenching is smaller than in other hosts. This material, NdLa pentaphosphate (Nd0.5La0.5P5O14) in the form of a 35-μm-thick crystal platelet was pumped with a pulsed Rhodamine 6G dye laser. The oscillation threshold with feedback from the uncoated surfaces was [inverted lazy s] 20 μJ of absorbed pump light. This indicates an optical gain coefficient of [inverted lazy s] 800 cm−1 corresponding to an excitation of more than half of the Nd ions in the material. This high gain resulted in a compression of the cavity mode spacing by a factor of 14. Using external mirrors, cw oscillation with a threshold of 25 mW absorbed power of an argon laser was achieved with a 1.4-mm-thick crystal. Measured parameters of the lasers are in good agreement with theory.
Optically stimulated x-ray laser
Authors: Freund Isaac
Published: January 2004

X-ray emission from the 2s → 1s transition in hydrogenic ions stimulated by an optical laser is proposed as a means of achieving lasing action in the x-ray region. A net gain of 0.27 cm−1 is calculated for the 18.97-Å 2s → 1s transition of O+7 at an inverted population density of 1015 ions/cm3 in the presence of a Nd laser field of 5 × 108 W/cm2.
Frequency-selective beam coupler for integrated optics
Authors: Ulrich R.
Published: January 2004

A second tunnel layer and an interference layer are added to a prism-film coupler. The resulting frequency response of the leak rate is given by the Airy formula for an interference filter. Strong coupling exists in the passband, whereas for stopband frequencies the guide and prism are decoupled. Experimentally, a bandwidth of 300 cm−1 in the visible is demonstrated. The underlying principle is also applicable to periodic couplers.
Bistable magnetic bubbles: Conditions leading to stability in liquid-phase epitaxial garnet films
Authors: Oeffinger T. R. , Roland G. W. , Braginski A. I. , Patterson R. W.
Published: January 2004

An abrupt hysteretic change in bubble size as a function of bias field has been observed in garnet films grown by chemical vapor deposition (CVD). Similar bistable bubbles and their associated transformations have now been observed in double-layer films grown by liquid-phase epitaxy (LPE). A slight compositional variation from layer to layer was introduced. Single-layer LPE films similar to CVD films reported earlier did not display these bistable bubbles. Compositional variations are postulated as the cause of the bistable bubbles, rather than strain variation as previously suggested.
Thermal stability of a proposed magnetic bubble metallurgy
Authors: Ziegler J. F. , Baglin J. E. E. , Gangulee A.
Published: January 2004

It has been proposed that Permalloy (Ni0.8Fe0.2) can be used as thin-film magnetic bubble generator and sensor, and Au is a proposed electrical connector for input/output. We find that significant interdiffusion occurs to levels of 1–10 at.% for the diffusion couples Ni/Au, Fe/Au, and Permalloy/Au. We have determined 350°C solubility levels for all pairs for 1100-Å films for annealing times from 10 to 2400 min. There was no degradation of electrical or magnetic properties of the Permalloy/Au system even at the highest levels of interdiffusion, indicating that it is ideally suited for a magnetic bubble metallurgy.
Explanation of laser-damage cone-shaped surface pits
Authors: Duthler C. J.
Published: January 2004

An anisotropic quasistatic stress distribution is found in the material surrounding an absorbing inclusion of a radius a centered a distance d below the surface of a transparent host. Maximum tensile stress greater than the pressure at the inclusion-host interface occurs at the angle Θm = cos−1(a/d) from the line joining the inclusion center to the surface, resulting in cone-shaped fracture.
Liquid-crystal optical activity for temperature sensing
Authors: Smith C. W. , Gisser D. G. , Young M. , Powers S. R.
Published: January 2004

In this letter, we report a novel temperature-sensing device based on the optical rotatory power of cholesteric liquid-crystal films. The transducer is small and compact, compatible with lasers and fiber optics, and capable of resolving temperature differences of 0.02 °C or better. It is simpler and more precise than most liquid-crystal techniques and does not pose the hazard that may be posed by electrical temperature sensors in certain applications. Dilute solutions of cholesteric liquid crystals in nematic solvents exhibit highly temperature-dependent optical rotation near the isotropic phase transition temperature. We place these solutions between crossed polarizers and measure the temperature by monitoring the transmission accurately. Using a laser source, we have installed a device of this nature at the end of a bundle of fibers with encouraging results.
Liquid phase epitaxy of GaAlAs on GaAs substrates with fine surface corrugations
Authors: Nakamura M. , Aiki K. , Umeda J. , Yariv A. , Yen H. W. , Morikawa T.
Published: January 2004

Liquid phase epitaxy of GaAlAs was performed on GaAs fine surface corrugations. By optimizing the growth conditions, GaAlAs layers were grown successfully with only minimal meltback.
Unequal electron and hole impact ionization coefficients in GaAs
Authors: Stillman G. E. , Wolfe C. M. , Rossi J. A. , Foyt A. G.
Published: January 2004

GaAs Schottky barrier avalanche photodiodes have been fabricated in which it is possible to achieve nearly pure hole and pure electron injection in the same device. Measurements of the multiplication characteristics of these devices show that the ionization coefficients of electrons (α) and holes (β) are not equal and that β>α. This result is in agreement with the variation of multiplication with bias voltage at different wavelengths observed for standard GaAs Schottky barrier diodes but contrary to the generally accepted belief that α=β.
Threshold condition for thin-film distributed-feedback lasers
Authors: Cordero Rodolfo F. , Wang Shyh
Published: January 2004

An exact solution to wave propagation in thin-film periodic structures using Bloch waves is presented and from it the threshold condition for distributed-feedback DFB lasers is derived. The form of the latter is identical to the oscillation condition of cavity lasers but with the appropriate reflection coefficients and propagation constant for Bloch waves substituted. We find that for laser action Bragg scattering alone is not sufficient but structural changes at both ends of the structure are necessary in order to produce appreciable reflection of the Bloch waves. Suggestions on how to achieve these reflections are given.
Stimulated emission from charge-transfer reactions in the afterglow of an e-beam discharge into high-pressure helium-nitrogen mixtures
Authors: Collins C. B. , Cunningham A. J. , Curry S. M. , Johnson B. W. , Stockton M.
Published: January 2004

Stimulated emission from the B2Σu+ state of N2+ has been observed as a consequence of the charge-transfer reaction between He2+ and N2 in the afterglow of a pulsed gigawatt electron beam discharge into 3 atm of helium containing 0.8 Torr nitrogen. Peak gains of the order of 0.05 cm−1 were found for the (0,1) vibrational component of the B 2Σu+→ X 2Σg+ transition at 4278 Å by directly measuring the time-resolved gain spectrum with a tunable dye laser. Correspondingly smaller gains were found for the (0,2) and (0,3) transitions of the same system at 4709 and 5228 Å, respectively.
Polarity-dependent memory switching in devices with SnSe and SnSe2 crystals
Authors: Chun Dongwoo , Walser R. M. , Bené R. W. , Courtney T. H.
Published: January 2004

Polarity-dependent memory switching has been observed in devices of crystalline SnSe and SnSe2 with aluminum contacts. Two types of low-level switching (1 V/1 mA) with reversed polarity dependence can be obtained in suitably formed devices of either material. In addition, a high-level (100 V/10 mA) polarized memory switching can be obtained in either device. The low-level switching appears to involve an electronic process, while the high-level switching is associated with an electrothermally driven mass transport.
Threshold reduction by the addition of phosphorus to the ternary layers of double-heterostructure GaAs lasers
Authors: Dyment J. C. , Nash F. R. , Hwang C. J. , Rozgonyi G. A. , Hartman R. L. , Marcos H. M. , Haszko S. E.
Published: January 2004

By the addition of phosphorus to the ternary layers of standard double-heterostructure GaAs injection lasers, significant reductions in lasing current threshold and increases in differential quantum efficiency have been obtained. Additional measurements suggest that the improvements are connected with a reduction in optical scattering loss.
PbxSn1-xTe epitaxial layers by rf multicathode sputtering
Authors: Corsi C. , Alfieri I. , Petrocco G.
Published: January 2004

Epitaxial single-crystal PbxSn1-xTe films with carrier concentration and mobility values close to bulk sinle crystals have been obtained by sputtering on BaF2, NaCl, and (111) Ge substrates.
Recombination without k-selection rules in dense electron-hole plasmas in high-purity GaAs lasers
Authors: Göbel G.
Published: January 2004

The low-temperature emission spectra of high-purity GaAs exhibit an intense new emission line at high optical pumping levels, which is due to band-to-band recombination within an electron-hole plasma. The experimentally determined gain spectra of this laser transition are fitted to calculated line-shape curves, which shows that the recombination takes place without k-selection rules.
Macroscopic deterioration of fluorescence from AlxGa1−xAs–GaAs DH material following microscopic physical damage
Authors: Johnston W. D.
Published: January 2004

The ``large dark spot'' (LDS) defect in AlxGa1−xAs–GaAs double-heterostructure (DH) laser material is identified as arising from elastic strain associated with microscopic physical damage. LDS are typically 100–200 μ wide as compared to submicron dimensions for the causative damage.
Surface depletion region width dependence of threshold voltage shift of ion-implanted MOS transistor
Authors: Kamoshida Mototaka , Kudoh Osamu
Published: January 2004

Even under the same implantation conditions, e.g., 50-keV 11B+ ions implanted through 1100-Å gate oxides on 4-Ω cm silicon substrates, the threshold voltage shift of n -channel MOS transistors is ∼55% of the shift of p -channel specimens, and deviation from linear dose dependence is observed for the n channel above a dose of 6×1011/cm2, while for a p -channel case the threshold voltage shift depends linearly on the net dose in silicon at least up to 1×1012/cm2. These results are discussed and explained with a calculated dose dependence that accounts for the large decrease of the maximum width of the depletion layer with increasing dose for acceptor-implanted n -channel specimens.
Superconductivity in AlN bistable resistance devices
Authors: Harris E. P.
Published: January 2004

The observation of superconductivity is reported in the low-resistance states of AlN bistable resistance devices. The data are interpreted as evidence in favor of the existence of a metallic microbridge between the device electrodes.
Nucleation and demagnetization by needle pricking in MnBi films
Authors: Kusuda Tetsuzo , Honda Shigeo
Published: January 2004

A study has been made of domain nucleation and propagation phenomena by pricking with a non magnetic needle a single-crystal MnBi film under zero external field perpendicular to the surface. The demagnetized pattern formed by needle pricking is very different from that of ``as-grown'' film. When a thicker part of the film (ratio of thickness to characteristic length h/lc∼100) is touched, the reversed domain encloses the pricking center and a hollow bubble is formed. The reversed domains emanate from the hollow bubble forming many bubble lattices with the initial magnetization, as if the Huygens wave spread from the source to the surrounding, and finally the crystal is demagnetized.
Application of gratings in fabricating arrays of superconducting and normal junctions
Authors: Tsang Won-Tien , Wang Shyh
Published: January 2004

Here we propose and demonstrate new applications of diffraction gratings, made on photoresists by optical interference of two laser beams, in fabricating one- and two-dimensional arrays of superconducting and normal junctions. By depositing metal films on photoresist gratings, it is possible to fabricate uniformly and closely spaced junctions. Junction arrays with submicron dimensions can be much more easily made with this technique than with the presently available techniques. Furthermore, the proposed technique offers the potential capability of producing more than 106 junctions per mm2 over an area of several cm2.
Transient laser phenomena in nematic liquid crystals subject to ac electric fields
Authors: Quon W. S. , Wiener-Avnear E.
Published: January 2004

A laser-induced orientation of the directions in a thin film of nematic liquid crystal subject to a low-frequency ac electric field has been observed. This phenomenon occurs at applied voltages just below the threhold voltage for Williams domain formation in the absence of the laser beam, and it manifests itself in the form of a very slow transient rise time for the appearance of the far-field diffraction pattern.
Structure of LiH to 12 GPa
Authors: Olinger Bart , Halleck P. M.
Published: January 2004

X-ray diffraction patterns at high pressure show that LiH retains the low-pressure NaCl structure to 12.0 GPa.
Laser oscillation in simple corrugated optical waveguide
Authors: Aoyagi Yoshinobu , Namba Susumu
Published: January 2004

The gain characteristics in a simple corrugated optical waveguide dye laser of Rhodamine 6G were observed. A new tuning method of lasing the wavelength of a DFB structure was examined.
Proton-induced characteristic x-ray analysis of Na and Cl impurity atoms in SiO2 thin films
Authors: Beezhold Wendland
Published: January 2004

Analysis of SiO2:Si and Au:SiO2:Si thin-film systems using proton-induced characteristic x rays (PIX) indicates that small quantities (≥1014/cm2) of Na and Cl atoms may be detected in SiO2 films even in the presence of strong O(K), Si(K), and/or Au(M) x-ray outputs. Distributions of implanted Na and contaminant Cl atoms were found to be stable during PIX analysis and for very high proton fluences. In contrast, heavy-ion Ne+ bombardment caused movement of Na and Cl within the oxide. Finally, PIX analysis of 50-keV Ar+ sputtering in Au:SiO2:Si shows that sputter profiling is complicated by strong ion-beam-induced intermixing of Au with SiO2 and of Au with Si.
Analytic solution of kinetic rate equations for HF chemical laser
Authors: Hunter A. M.
Published: January 2004

The species rate equations corresponding to the F+H2 chemical reaction have been solved analytically to obtain the populations of the individual HF vibrational levels. The solution of each vibrational level contains terms representing direct chemical pumping, cascading from all higher levels, and deactivation. Analytic and numerical solutions for the specie densities and the corresponding small-signal gains are in excellent agreement for well-diluted gas mixtures.
Low-loss single-mode optical waveguides and efficient high-speed modulators of LiNbxTa1−xO3 on LiTaO3
Authors: Hammer J. M. , Phillips W.
Published: January 2004

Low-loss LiNbxTa1−xO3 optical waveguides have been made by a simple diffusion technique. They are used to demonstrate over 80% base band electro-optic modulation with frequency capabilities extending to the microwave range. Voltages below 5 V and drive powers below 2/10 mW/MHz are required.
Two-layered construction of integrated optical circuits and formation of thin-film prisms, lenses, and reflectors
Authors: Tien P. K. , Riva-Sanseverino S. , Martin R. J. , Smolinsky G.
Published: January 2004

We have demonstrated a new form of a two-layered construction of optical circuits. In this method, thin-film optical devices are covered by a single continuous layer of light-guiding film which serves as the interconnections as well as the input and output terminals. We also have demonstrated the construction of thin-film prisms, lenses, and a novel corner reflector in this type of structure.
Calibrated remote measurement of NO2 using the differential-absorption backscatter technique
Authors: Grant W. B. , Hake R. D. , Liston E. M. , Robbins R. C. , Proctor E. K.
Published: January 2004

A tunable dye laser, operating between 4400 and 4500 Å, was used to monitor NO2 concentrations in a sample chamber 365 m away. The atmosphere in front of and behind the chamber acted as a distributed reflector to send laser light back through the chamber to a receiver near the laser. The laser measurements agreed well with in situ measurements. A single pair of laser pulses allowed the determination of NO2 concentrations with an uncertainty equivalent to 0.05 km ppm.
Integrated optical waveguide examination using anti-Stokes fluorescence
Authors: Ostrowsky D. B. , Roy A. M. , Sevin J.
Published: January 2004

The local fields propagating in integrated optical waveguides have been examined by coating the guide with a material containing Rhodamine B. The Rhodamine absorbs a portion of 6328-Å light propagating in the guide and emits light centered at 5950 Å via an anti-Stokes emission process. The intensity of the anti-Stokes emission at a given point is proportional to the local 6328-Å intensity. Since the anti-Stokes light is not guided, it is easily observable and has permitted the visualization of a light-guided phenomenon which was previously unobservable in integrated optical microstructures.