bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser-induced damage in ZnSe
Authors: Fradin D. W. , Bua D. P.
Published: January 2004

Pulsed laser damage in CVD-grown ZnSe has been studied at 1.06 and 10.6 μ. At 1.06 μ the intrinsic damage intensity was measured to be 1.2 GW/cm2. Damage at 10.6 μ was observed to be the result of inclusion absorption with the damage intensity dependent on focused beam diameter. A statistical model of inclusion damage is developed to account for this dependence. By comparing the predictions of the model to damage intensities measured under two conditions of external focusing, the average density of potentially damaging inclusions is calculated to be about 107 cm−3.
Field-effect conductance change in amorphous silicon
Authors: Malhotra A. K. , Neudeck G. W.
Published: January 2004

The change in conductance of an amorphous silicon film due to a transverse electric field was observed. The films were electron-beam vacuum deposited at controlled rates of less than 5 Å/sec onto Si–SiO2 substrates and then annealed for 4 h at 400 °C. The results indicate that the Fermi level is not pinned at near midgap and that the localized states are nearly uniform over a 0.4-eV section above and 0.4 eV below the Fermi level near the middle of the energy gap. Calculations show the density of localized states to be 1020/eV cm3 over this region and to be reduced as the deposition rate decreases.
Liquid phase epitaxial growth of laser heterostructures in Pb1−xSnxTe
Authors: Tomasetta L. R. , Fonstad C. G.
Published: January 2004

Pb1−xSnxTe heterostructures have been grown by liquid phase epitaxy on p-PbTe substrates and laser diodes have been fabricated from layered structures with the following compositions: n-PbTe (LPE)/p-PbTe (substrate); n-Pb1−xSnxTe (LPE)/p-PbTe (substrate); and n-PbTe (LPE)/n-Pb1−xSnxTe (LPE)/p-PbTe (substrate). Lasing in all structures occurs in the lower-band-gap region. Threshold currents in these lasers are comparable to those reported for conventional diffused lasers, indicating that the presence of the heterojunctions does not introduce a significant number of new nonradiative recombination centers and that efficient minority carrier injection occurs across the heterojunctions. The liquid phase epitaxy technique used in these growths is discussed.
Electron bombardment of electret foils
Authors: Perlman M. M. , Unger S.
Published: January 2004

A study of electron trapping as a function of (Teflon) sample temperature during irradiation is carried out using the thermally stimulated current technique. Results show that bombardment should take place at elevated sample temperature if one desires a long-lived stable electret. The effect of sample thickness and of a partial discharge onto the sample after irradiation is also investigated. Both molecular motion and thermal excitation seem to play a role in charge release.
Radiation-induced thermally activated polarization transfers in CaF2
Authors: Podgorsak Ervin B. , Moran P. R.
Published: January 2004

The strong radiation-induced thermally activated depolarization (RITAD) effect previously reported in CaF2 can be identified with a corresponding polarization (RITAP) phenomenon. These RITAP and RITAD effects are orders-of-magnitude more radiation sensitive than radioelectret phenomena and consist of polarization transfers among electron, hole, and ionic-charge transport states of the material. Net sample polarization is independent of radiation exposure for exposures smaller than 103 R.
Conversion of 28-μ far-infrared radiation to visible light using bound excitons in CdS
Authors: Gundersen Martin
Published: January 2004

A process for the conversion of far-infrared radiation to visible light in CdS is reported which is sensitive to a band of infrared. Two exciton levels are utilized, the lower of which is pumped by a visible light source. It is not required that the visible or the infrared be resonant between the two levels.
Optical recording of digital data in PLZT ceramics
Authors: Micheron F. , Rouchon J. M. , Vergnolle M.
Published: January 2004

Digital data are recorded in nonpolar PLZT ceramics using the photoinduced change of refractive index at wavelength λ=488 nm under applied electric field. This process allows electrical selection and addition of two recorded images and selective optical erasure. It is interpreted in terms of the quadratic electro-optic effect and local electric field amplitudes in the illuminated regions, computed as sums of the applied field and internal screening fields due to displacements and trapping of photoexcited charge carriers.
Organic recording medium for volume-phase holography
Authors: Bloom Allen , Bartolini Robert A. , Ross Daniel L.
Published: January 2004

A new organic recording medium for volume-phase holography is described. Holograms can be read out nondestructively at the recording wavelength and power. Self-erasure may also be obtained. Holographic data and the effect of structure on recording and fixing behavior are described. The recording medium may be used to record multiple holograms.
Optical detection in thin-film metal-oxide-metal diodes
Authors: Gustafson T. K. , Schmidt R. V. , Perucca J. R.
Published: January 2004

Planar metal-oxide-metal diodes having cross-sectional areas as small as 10−8 cm2 have detected optical radiation. Several possible detection mechanisms, including optical rectification, are discussed.
Lithium niobate ridge waveguide modulator
Authors: Kaminow I. P. , Ramaswamy V. , Schmidt R. V. , Turner E. H.
Published: January 2004

A narrow ridge was ion-beam etched on an outdiffused LiNbO3 crystal to form a single-mode waveguide confining the beam in both transverse dimensions. Electrodes were evaporated along the ridge to produce a very efficient electro-optic phase modulator requiring a power of 20 μ W/MHz of bandwidth and a voltage of 1.2 V to produce a modulation index of 1 rad.
Conversion gain in a Josephson effect mixer
Authors: Taur Y. , Claassen J. H. , Richards P. L.
Published: January 2004

The measured performance of Nb–Nb point contact Josephson junctions used as 36-GHz microwave mixers is in good agreement with the predictions of the resistively shunted junction model. Conversion efficiencies greater than unity are attained, with mixer noise temperatures comparable with the best competing devices.
Structure of catalysts: Determination by EPR and Fourier analysis of the extended x-ray absorption fine structure
Authors: Lytle Farrel W. , Sayers Dale E. , Moore Emmett B.
Published: January 2004

An alumina-supported CuCr catalyst was examined with the extended x-ray absorption fine-structure (EXAFS) technique. This is a new technique which can determine the chemical states and near-neighbor environments of the separate Cu and Cr atomic species. Cu was found to occupy both tetrahedral and octahedral sites in the supporting alumina lattice while Cr was found only in octahedral sites. The valence state was Cr+5 in the fresh catalyst which changed to Cr+6 in the exhaust-cycled material. Confirmation of the valence state assignment was obtained by EPR. Fourier analysis of the EXAFS produced separate radial structure functions for the Cu and Cr atoms since the experiment measures the properties of the individual atomic species rather than those of the structure as a whole. Significant differences were observed by both techniques between fresh and exhaust-cycled material.
Observations on the formation and etching of platinum silicide
Authors: Rand Myron J. , Roberts James F.
Published: January 2004

When thin-film platinum and single-crystal silicon are interdiffused, [inverted lazy s] 100 Å of SiO2 is found at the PtSi surface. The silica protects the silicide from attack by the aqua regia commonly used to remove unreacted Pt. If the silica is stripped, PtSi on Si will dissolve in aqua regia even faster than Pt. These findings are applicable to contact technology for silicon devices and integrated circuits.
Memory switching in ion-exchanged oxide glasses
Authors: Chakravorty D.
Published: January 2004

Memory switching has been observed in the surface layers of certain multiphase glasses which have been subject to Na+⇄Ag+ ion exchange followed by a reduction treatment in hydrogen. A possible mechanism is discussed in the light of the microstructural characteristics of these glasses.
Second harmonic generation and infrared mixing in AgGaSe2
Authors: Byer R. L. , Choy M. M. , Herbst R. L. , Chemla D. S. , Feigelson R. S.
Published: January 2004

We have continuously tuned between 7 and 15 μm by mixing the output of a LiNbO3 parametric oscillator in the chalcopyrite AgGaSe2. We have doubled a CO2 laser with 2.7% efficiency which agrees very well with the expected efficiency and verifies the high optical quality of the 1.53-cm-long AgGaSe2 crystal. The measured transparency range, indices of refraction, and nonlinear coefficient of d36 = (3.7 ± 0.6) × 10−11 m/V show that AgGaSe2 is a useful infrared nonlinear material phase matchable over the entire 3–18-μm infrared region.
Optical gating and logic with pyroelectric crystals
Authors: Glass A. M. , Negran T. J.
Published: January 2004

Optical gating with LiTaO3 single crystals is demonstrated using an absorbing LiTaO3:Cr detector directly coupled to a LiTaO3 electro-optic modulator. Since no electrical power is required, such a gating scheme provides a simple basis for optical logic in pyroelectric waveguides.
New method for electro-optical tuning of tunable lasers
Authors: Telle John M. , Tang C. L.
Published: January 2004

A new scheme for electro-optical tuning of tunable lasers is described. Tuning rates and tuning ranges in cw dye lasers nearly 100 times greater than those previously reported using a comparable-sized electro-optical crystal have been achieved using this method.
Effects of ion radiation damage on the magnetic domain structure of amorphous Gd–Co alloys
Authors: Gambino R. J. , Ziegler J. , Cuomo J. J.
Published: January 2004

We have subjected sputtered amorphous films of Gd–Co alloys to a high-energy argon ion flux to study the effects of ion radiation damage on the uniaxial anisotropy of these materials. We find that a relatively low level of radiation damage ([inverted lazy s] 1014 ions/cm2) can destroy the uniaxial anisotropy if the damage is sustained in zero applied fields. A similar dosage can induce anisotropy if a strong magnetic field is applied during the ion irradiation. These experiments support the atomic-pair-ordering model of anisotropy in these materials.
Fabrication of submicron LiNbO3 transducers for microwave acoustic (bulk) delay lines
Authors: Huang H. C. , Knox J. D. , Turski Z. , Wargo R. , Hanak J. J.
Published: January 2004

The technology for fabrication of submicron bulk platelet transducers has been developed. Lithium niobate (LiNbO3) transducers with thicknesses as low as 0.25 μm have been achieved. This technology employs a novel bonding technique, the room-temperature vacuum bond, and a carefully controlled process of ion-beam milling. Bulk wave acoustic delay lines consisting of LiNbO3 transducers on spinel (MgAl2O4) substrate have yielded very wide-band and low-loss operation in S-, C-, and X-band frequencies.
Liquid crystal Lichtenberg figure
Authors: Sone Mototaka , Toriyama Kazuhisa , Toriyama Yotso
Published: January 2004

A new method for delineation of surface discharge figures on insulating surfaces is described. Cholesteric liquid crystal thin films on insulating surfaces finely delineate structures of residual charges of surface discharges on them. The method has high resolving power (∼ 1 μm) in the delineation of the surface discharges.
Use of Schottky-diode collectors for SEM determination of bulk diffusion lengths
Authors: van Opdorp C. , Peters R. C. , Klerk M.
Published: January 2004

Schottky diodes were used as collectors in the determination of bulk hole diffusion lengths (Lhn) by means of a scanning electron microscope in the beam-induced current mode. The scans were performed on cross sections obtained by cleavage along a plane perpendicular to the metal layer. For n-type GaP this technique yields excellent results.
Experimental verification of density inhomogeneity due to lasing in a gas-dynamic laser
Authors: Fuhs A. E. , Biblarz O. , Cawthra J. K. , Campbell J. L.
Published: January 2004

As a consequence of lasing, heat, in an amount related to the quantum efficiency, is released in a gas-dynamic laser (GDL) causing density perturbations, Calculations were made to predict the density contours throughout the laser cavity. Subsequent to the calculations, density changes due to lasing were measured using a Mach-Zehnder interferometer. The predicted and observed density variations were in good agreement.
Experimental determination of highly concentration-sensitive effects of intervalley electron-electron scattering on electric-field-dependent repopulation in n-Si at 77 K
Authors: Nash James G. , Holm-Kennedy James W.
Published: January 2004

Measurements have been made of current density versus electric field on < 111 > and < 100 > oriented samples of n-Si at 77 K with resistivities ranging from 0.050 to 200 Ω cm. These have been analyzed to yield the concentration and field dependence of repopulation resulting from a < 100 > application of electric field. The magnitude of the repopulation has been found to be extremely sensitive to the free-carrier concentration. This sensitivity is attributed to the energy exchange effects of intervalley electron-electron scattering. The repopulation provides a new and highly selective experimental parameter for use in the study of electron-electron scattering in semiconductors.
Investigation of a superconducting niobium X-band deflecting cavity
Authors: Aggus J. R. , Bauer W. , Giordano S. , Hahn H. , Halama H. J.
Published: January 2004

A 8.665-GHz deflecting cavity, machined from solid niobium, electron beam welded, chemically polished, anodized and heat treated, yielded a peak magnetic field of 740 G corresponding to a peak electric field of 25 MV/m and a deflecting field of 6.9 MV/m. The maximum Q value was 4.5 × 109. Based on these results, design parameters and suggestions for the fabrication of an X-band rf beam separator are given.
Microwave impedance of a thin-film superconducting ring containing a Notarys proximity effect weak link
Authors: Rachford F. J. , Huang C. Y. , Wolf S. , Nisenoff M.
Published: January 2004

The properties of thin tin film superconducting rings containing a proximity effect weak link have been measured at 9.2 GHz. The impedance exhibits steps which at low order are uniformly spaced and are not hysteretic. The magnitude of the field-modulated component of the power reflected from the cavity resonant at 9.2 GHz is approximately 102 times larger than the signal obtained at 30 MHz and has a signal-to-noise ratio of 104 in a 10 cycle bandpass. Higher-order steps exhibit unexpected features which might be due to the fact that the time between flux entry is comparable to the quasiparticle relaxation time.
Acousto-optic deflection in Ta2O5 waveguides
Authors: Wille Douglas A. , Hamilton Michael C.
Published: January 2004

Surface acoustic waves on quartz have been used for acousto-optic deflection in Ta2O5 waveguides. Deflection efficiencies for TM modes of up to 93% have been observed with an acoustic power of 175 mW.
Effect of inelastic energy loss on CO2 laser breakdown of gases
Authors: Hacker M. P. , Cohn D. R. , Brooks R. L.
Published: January 2004

The pressure dependence of the threshold energy for CO2 laser gas breakdown in helium and nitrogen has been measured in the pressure range 40–70 Torr. The striking difference in the pressure dependence for the two gases is a clear manifestation of the effect of inelastic energy losses upon the avalanche breakdown process. This difference can be predicted by simple physical arguments or by scaling results from dc gas breakdown experiments to CO2 frequency.
Focal-length dependence of air breakdown by a 20-psec laser pulse
Authors: Ireland C. L. M. , Yi A. , Aaron J. M. , Morgan C. Grey
Published: January 2004

The focal-length f and beam-diameter D dependence of threshold power for air breakdown has been investigated using focused ∼20-psec 1.06-μ laser pulses. Primary spherical aberration is shown to be very important in determining the threshold power when D/f is large. Diffusion-type losses and self-focusing played no part in the breakdown mechanism in the present work.
Trace-element detection method based on coherent scattering of radiation
Authors: Church D. A. , Hadeishi T.
Published: January 2004

The detection and measurement of trace quantities of mercury in air by a magneto-optic coherent forward-scattering technique is described. The method is characterized by high sensitivity and selectivity, and is applicable to a broad class of elements.
Liquid-phase epitaxial growth of (AlGa)As on polished and roughened GaP substrates for transmission photocathodes
Authors: van Oirschot T. G. J.
Published: January 2004

It is shown that growth of smooth layers of (AlGa)As on GaP by liquid phase epitaxy (LPE) can be achieved if the GaP substrate surface possesses a certain degree of roughness when growth starts. This roughness can be introduced by various methods, including preferential chemical etching or in situ melt-back, but the best surface morphology of the epitaxial layer is obtained after mechanical lapping of the substrate. This striking phenomenon is attributed to an increase of the density of nuclei which results in a more uniform distribution of the grains characteristic for this system with large lattice mismatch.
Observation of noncritically phase-matched second-harmonic generation in an optical waveguide
Authors: Burns W. K. , Lee A. B.
Published: January 2004

Experimental observation of noncritically phase-matched second-harmonic generation in a liquid/TiO2/quartz waveguide is reported. The phase-match condition, approximately independent of waveguide thickness, was achieved by tuning the liquid refractive index. Nonlinear interaction occurs in the quartz between the fundamental (1.06 μm) TE0 mode and the harmonic (0.53 μm) TM0 mode. Mode effective indices were measured versus liquid index to determine the phase-match point. Coherence lengths greater than 3.5 mm were achieved, but propagation lengths were limited to 4 mm by losses due to surface scattering. These losses arise from waveguide design requirements of noncritical phase matching, not experimental film quality. Conversion efficiency was approximately 0.01%.
cw laser diodes and high-power arrays of InxGa1−xAs for 1.06-μm emission
Authors: Nuese C. J. , Ettenberg M. , Enstrom R. E. , Kressel H.
Published: January 2004

InxGa1−xAs (x ∼0.23) p-n junction lasers have been prepared which are capable of providing continuous-wave (cw) operation at 1.085 μm at 77°K, and which emit 64 mW of coherent radiation at a current level of 1 A. Twelve-element series-connected laser arrays of InxGa1−xAs also have been fabricated, which emit more than 21 W of (peak) 1.058-μm radiation at 77°K when driven at a (pulse) current level of 8 A.
Resonantly two-photon pumped frequency converter
Authors: Harris S. E. , Bloom D. M.
Published: January 2004

This letter describes a resonantly two-photon pumped frequency converter with application to the generation of tunable ultraviolet and vacuum ultraviolet radiation and also to infrared-to-visible up-conversion and imaging. Calculations show that up-conversion power efficiencies in excess of 100% should be obtainable with tunable dye lasers having peak powers in the hundred watt to kilowatt range.
Determination of absolute frequencies of 12C16O and 13C16O laser lines
Authors: Eng R. S. , Kildal H. , Mikkelsen J. C. , Spears D. L.
Published: January 2004

The absolute frequencies of one 13C16O and seven 12C16O laser lines have been determined with an uncertainty of about ±5 MHz by measuring the beat frequencies between these CO lines and second harmonics of CO2 laser transitions generated in a CdGeAs2 frequency-doubling crystal. Beat frequencies up to 11 GHz have been measured using a high-speed HgCdTe detector.
Speculation on the possibility of a battery or fuel cell based on ionic diffusion through a Schottky barrier
Authors: Schoijet Mauricio
Published: January 2004

We suggest that a battery or fuel cell might be built using ionic diffusion through a Schottky metal-semiconductor barrier, if the ionic current given by Fick's law is significantly larger than the electronic current given by Richardson's law. The possible values of the relevant parameters necessary for observing the effect—barrier height, diffusion coefficient, and ionic state of the impurity—are discussed. The effect might be observed for a fast-diffusing impurity and for a concentration of the order of 1019 cm−3—both conditions being fulfilled by Li in rutile—and for a barrier height of the order of 0.8 eV. For a H2–O2 fuel cell the barrier height would have to be 1.1 eV. No impurity-metal-semiconductor system has been found for which all relevant parameters are known and that satisfies our requirements, but it is suggested that rare-earth semiconductors might have some of the desired properties.
Optically pumped electric-discharge uv laser
Authors: Brown Robert T. , Smith David C.
Published: January 2004

A new technique for pumping uv laser transitions is described. The technique consists of using an intense 10.6-μ laser pulse to drive a diffuse discharge in a preionized uv laser medium. Because of its fast rise time, high electron density, and ability to operate at high pressure, this discharge is well suited to pumping uv laser transitions. Experimental results are shown for the application of this technique to the 3371-Å transition in nitrogen. A diffuse discharge at atmospheric pressure was obtained, and an intense pulse of 3371-Å radiation was observed.
Pulsed electron-beam-initiated chemical laser operating on the H2/F2 chain reaction
Authors: Aprahamian R. , Wang J. H. S. , Betts J. A. , Barth R. W.
Published: January 2004

Pulsed HF and DF chemical lasing has been observed in SF6:F2:H2 and SF6:F2:D2 mixtures, respectively, using an electron beam to initiate the laser reactions. Maximum pulse energies of 50 J with peak output power of 50 MW and an electrical efficiency of 6% were obtained with a 4195-cm3 active volume, a total pressure of 240 Torr, and gas component ratios SF6:H2:F2 of 1.33:1.0:1.0. For an active volume of 236 cm3, a total pressure of 420 Torr, and SF6:H2:F2 equal to 1.5:1.0:1.0, 11 J energy was obtained corresponding to an energy density of 80 J/l atm. For DF lasing from mixtures of SF6, D2, and F2, the output energy is a factor of 2–3 smaller than for HF lasing from mixtures of SF6, H2, and F2 with the same initial conditions.
Remote detection of CO by parametric tunable laser
Authors: Henningsen T. , Garbuny M. , Byer R. L.
Published: January 2004

Resonance absorption of the radiation from a parametrically tuned laser permits the remote detection and density measurement of pollutant gases at large ranges with single-ended systems if topographical features or atmospheric aerosol are used as backscattering means. We have built and demonstrated such a transmitter-receiver system operating at 2.3 μm in the infrared. The presence and amount of a CO sample placed at a range of 107 m against a topographical backscattering target was established by the absorption of rotational lines in the first overtone transition. The results indicate a range limit of the present equipment at 1.5 km and a sensitivity in good agreement with predictions based on measured linewidths and cross sections.
Elimination of dislocations in heteroepitaxial layers by the controlled introduction of interfacial misfit dislocations
Authors: Rozgonyi G. A. , Petroff P. M. , Panish M. B.
Published: January 2004

A procedure for the elimination of dislocations in layers of GaAlAsP on GaAs substrates has been developed and is described in this report. By carefully controlling the layer thickness and the lattice parameter mismatch at the growth temperature it is possible to change the direction of substrate dislocations as they enter the substrate/layer interface. The length of the dislocation in the interfacial plane can be extended such that it is ``infinitely'' long, i.e, it reaches the edge of the wafer.
Theory of formation of phase holograms in lithium niobate
Authors: Young L. , Wong W. K. Y. , Thewalt M. L. W. , Cornish W. D.
Published: January 2004

The production of refractive-index gratings by photoexcitation of electrons from traps followed by drift or diffusion and then retrapping is treated without the assumption made by Amodei that the migration or diffusion length is small compared to the grating wavelength. It is shown that the efficiency of hologram writing increases with increasing diffusion or migration length up to a certain limit. The spatial shift between the refractive-index grating and the light-intensity pattern which produces it is different according to whether drift or diffusion is operative only for short drift lengths.
Mode conversion in magneto-optic waveguides subjected to a periodic Permalloy structure
Authors: Tseng S. C.-C. , Reisinger A. R. , Giess E. A. , Powell C. G.
Published: January 2004

A new method to achieve periodic reversals of magnetization, necessary to attain high mode conversion efficiencies in magneto-optic waveguides, is described. It is acomplished by means of a periodic Permalloy structure overlaying the optical propagation path. With proper bias fields, we have observed an optimum dc conversion efficiency of 80±2% at 1.15 μm in a Gd0.5Ga1 iron garnet film guide.
Hologram storage in photochromic LiNbO3†
Authors: Staebler D. L. , Phillips W.
Published: January 2004

The incorporation of Mn in Fe-doped LiNbO3 leads to photochromic behavior involving photoreversible conversion of Fe3+ to Fe2+. This process can be used to advantage to control the holographic storage sensitivity of the material.
ac electron tunneling at infrared frequencies: Thin-film M-O-M diode structure with broad-band characteristics
Authors: Small J. G. , Elchinger G. M. , Javan A. , Sanchez Antonio , Bachner F. J. , Smythe D. L.
Published: January 2004

A high-speed diode element consisting of a metal-metal-oxide-metal electron-tunneling junction is formed by thin films deposited on a substrate. These junctions are integrated with deposited narrow resonant antenna structures which couple the junction to incident radiation. Broad-band characteristics from radio and microwave frequencies to the infrared region are shown. Frequency mixing and the possibility of utilizing large numbers of elements simultaneously are also demonstrated.
Generation of bandwidth-limited pulses from a TEA CO2 laser using p-type germanium
Authors: Gibson A. F. , Kimmitt M. F. , Norris B.
Published: January 2004

Passive mode locking of a TEA CO2 laser using p-type germanium as a saturable absorber is described. Pulses of about 0.5-ns duration are obtained.
Spontaneous and stimulated carrier lifetimes (77°K) in GaAs1−xPx and GaAs1−xPx : N
Authors: Lee M. H. , Holonyak N. , Campbell J. C. , Groves W. O. , Craford M. G. , Keune D. L.
Published: January 2004

By means of optical phase shift measurements at low and high excitation levels, spontaneous and stimulated carrier lifetimes are determined (77°K) as a function of photon energy on nitrogen-doped and nitrogen-free n-type GaAs1−xPx. Spontaneous lifetime data near laser threshold on N-free samples show the effect of stimulated emission and intraband adjustment of electrons during sample fluorescence. Above threshold the lifetime drops sharply in the vicinity (energy or wavelength) of the sample peak laser output. Nitrogen-doped samples show, in addition, the effect of electron transfer from the conduction band to the NN-pair states, supporting in the process laser operation on the nitrogen states.
Zinc ion implantation into GaAs0.62P0.38
Authors: Itoh Tadatsugu , Oana Yasuhisa
Published: January 2004

The effects of dose, implantation temperatures, and annealing on the electrical properties of Zn-implanted GaAs0.62P0.38 were measured. Zinc ion implantation was performed with 20-keV ions at temperatures between room temperature and 450 °C. The abnormal property that the effective surface concentration exceeds the implanted Zn dose was obtained for the samples implanted at room temperature.
Degradation-induced microwave oscillations in double-heterostructure injection lasers
Authors: Yang E. S. , McMullin P. G. , Smith A. W. , Blum J. , Shih K. K.
Published: January 2004

Microwave oscillations in the light output of mesa-stripe GaAs–Ga1−xAlxAs double-heterostructure lasers have been observed after degradation. The same lasers showed no oscillations before degradation. The experimental evidence indicates that the oscillations are caused by repetitive Q switching, with dark-line regions in the degraded units acting as saturable absorbers.
Threshold effects and large Tc reductions in neutron-irradiated A-15 superconductors
Authors: Schweitzer Donald G. , Parkin Don M.
Published: January 2004

A-15 superconductors show very large decreases in critical temperature after 60 °C neutron irradiations exceeding about 1018 neutrons/cm2 (E>1 MeV). These effects are not observed in superconductors such as Nb, NbN, or Nb–Ti.
Residual surface resistance of superconductors at microwave frequencies
Authors: Kartheuser E. P. , Rodriguez Sergio
Published: January 2004

A microscopic theory of the residual surface resistance is presented and compared with experimental results in superconducting lead and niobium. It is shown that for frequencies above 1 GHz, direct electromagnetic generation of acoustic shear waves can account for the measured residual surface resistance.
Effect of pulse shaping on laser-induced spallation
Authors: Fox Jay A.
Published: January 2004

Photographic evidence is presented of the back-face spallation of 1.0-mm 6061-T6 aluminum samples irradiated in vacuum by 1.5-nsec 1.06-μ laser pulses. Thinner samples (0.5 mm) have also been spalled and complete back-face separation has been achieved. It is demonstrated that the degree of spallation is a strong function of fluence and that target coupling can be enhanced by means of prepulses.
Radiation hardening and pressure-actuated charge release of electron-irradiated Teflon electrets
Authors: Gross B. , Sessler G. M. , West J. E.
Published: January 2004

The radiation-induced conductivity (RIC) of Teflon is greatly reduced after bombardment with massive doses of the order of 100 Mrad. Such a ``radiation-hardened'' Teflon film can store a considerably larger amount of negative charge in vacuum than nonhardened Teflon films. The stored charge is, however, released within a short time when the dielectric is brought up to air pressure. This charge release occurs partly as disruptive internal discharge at pressures below 1 Torr and partly as continuous charge release at higher pressures.
Performance of the all-metal-wall theta pinch
Authors: Naraghi M.
Published: January 2004

An all-metal-wall theta pinch has been constructed by stacking 200 anodized aluminum rectangular rods in order to form a cylindrical shell. Measurements by magnetic probes have shown the separation of current sheet from the metal wall in cases where the potential difference between two adjacent rods has been 25 V. Temperature measurements in helium plasma have shown higher temperatures when metal is used rather than dielectrics.
Nonlinear correction to Ohm's law derived from Boltzmann's equation
Authors: Havemann R. H. , Engel P. F. , Baird J. R.
Published: January 2004

The validity of Ohm's law is examined for the case of electric fields which are changing either in amplitude or direction over distances comparable to one electron mean free path within a metal. By perturbing both the amplitude and spatial variation of the electric field, an approximate solution of Boltzmann's equation is obtained which yields a first-order correction to Ohm's law that is, in general, not in the same direction as the linear J = σE term. The nonlinear term is quadratic in the electric field amplitude and depends on the spatial derivatives of the electric field.
CO2-laser-driven detonation waves in the presence of a strong magnetic field
Authors: Halverson W.
Published: January 2004

CO2-laser-driven detonation fronts have been studied in low-pressure hydrogen and helium with axial magnetic fields up to 88 kG. At pressures above 100 Torr the shock front propagates toward the laser and the magnetic field has no observable effect. At lower pressures and no field, plasma fronts move both toward and away from the laser. The 88-kG field confines the plasma radially and causes the ``downstream'' front to disappear. The shock motion is well described by the modified detonation model of Daiber and Thompson.
Infrared waveguides in thin films of CdS
Authors: Stanley C. R. , Duncan W. , McMurray J. A.
Published: January 2004

Laser radiation at 1.15 μm has been guided in thin films of CdS which were evaporated onto both glass and quartz substrates in a UHV system. The infrared radiation was coupled into and out of the films by both prisms and ion-etched gratings, and a minimum propagation loss for the TE0 mode of less than 5 dB cm−1 was measured. A small birefringence was observed in these experiments, Δn = nTM − nTE≃0.01.
Distortionless propagation of zero-degree pulses in degenerate resonant medium
Authors: Lu Eugene Y. C. , Wood L. E.
Published: January 2004

We give arguments to show that distortionless propagation of zero-degree pulses is possible in an arbitrary degenerate resonant medium in agreement with recent experimental observation. In the case of overlapping Q (2) degeneracy, the analytic closed-form solution with zero area is given. The predicted pulse shape depends in the relative occupation of the degenerate levels and should be observable experimentally.
A broadly tunable cw laser using color centers
Authors: Mollenauer L. F. , Olson D. H.
Published: January 2004

cw laser action in an optically pumped Li-doped KCl crystal containing FA (II) centers has been demonstrated. The laser wavelength was continuously tunable over the range 2.6–2.8 μm. Pump power at threshold was 50 mW, and threshold powers in the submilliwatt range can be predicted for an improved cavity design. Laser action was obtained for crystal temperatures in the range 77≲ T ≲ 200 °K.
Singly resonant CdSe parametric oscillator pumped by an HF laser
Authors: Weiss Joel A. , Goldberg Lawrence S.
Published: January 2004

A transverse excitation HF laser has been used to pump a singly resonant CdSe infrared parametric oscillator. Tunable output has been generated over the range 4.3–4.5 μm and 8.1–8.3 μm with peak powers of up to 800 W. By a combination of angle tuning and selection of HF pump wavelength, CdSe is phase matchable for generation of radiation from 3.0–4.8 μm and 7.8–22 μm.
Temperature dependence of exchange stiffness in garnet bubble films
Authors: Slonczewski J. C. , Malozemoff A. P. , Giess E. A.
Published: January 2004

The temperature dependence of the exchange stiffness is taken into account to predict the room-temperature exchange stiffness of substituted YIG films for bubble applications. A simple theory leads to the linear relation of A(T,TN) = AYIG(T)[TN−T)/(TN, YIG −T)] where AYIG(T) is the exchange stiffness of YIG at the ambient temperature T and A(T,TN) is the exchange constant at T of a film with Neél temperature TN. This relation is in reasonable agreement with the recent spin-wave resonance data of Henry and Heinz.
Analysis of acoustic bulk mode excitation, by interdigital transducers
Authors: Wagers R. S.
Published: January 2004

It is shown that for surface wave delay lines with parallelepiped substrate geometry, the plate modes of the substrate describe the entirety of the spurious responses of the transducers. Experimental evidence is presented which shows that by carrying out a superposition of the plate modes, both the in-band distortion and the out-of-band rejection can be quantitatively predicted.
Amplification of surface acoustic waves by transverse electric current in piezoelectric semiconductors
Authors: Gulyaev Yuri V.
Published: January 2004

It is shown that the principal characteristic feature of the surface acoustic waves in piezoelectrics—the presence of an alternating electric field transverse to the surface, which can be of the same order of magnitude as the longitudinal field—may not only give rise to the known transverse acoustoelectric effect but also lead to amplification of surface acoustic waves by electron drift perpendicular to the surface. For Love waves in a piezoelectric semiconductor film on a highly conducting substrate, the amplification coefficient is found and the conditions necessary for amplification are investigated.
Harmonic generation and frequency mixing in laser-produced plasmas
Authors: Lee Ping , Giovanielli D. V. , Godwin R. P. , McCall G. H.
Published: January 2004

Spectral measurements of light scattered at various angles from a laser-produced plasma were made at the laser frequency ωL, and at ωL/2, 3ωL/2, 2ωL, 5ωL/2, and 3ωL using a mode-locked Nd:glass laser to produce intensities of 1016 W/cm2 at the target. Signals were detected at ωL, 3ωL/2, and 2ωL, and their intensities relative to the incident intensity were determined. Upper bounds were set for the intensities at the other frequencies.
Effects of ionizing radiation on transmission of optical fibers
Authors: Sigel G. H. , Evans B. D.
Published: January 2004

The spectral character of the optical absorption produced by ionizing radiation in several fibers and fiber materials has been measured. The nature of the damage has been identified in some of the samples and preliminary work has been successful in synthesizing radiation-protected soda lime silicate glasses for fiber applications.
Gallium phosphide latching diode
Authors: Peaker A. R. , Hamilton B.
Published: January 2004

A new type of green-light-emitting negative-resistance gallium phosphide diode has been produced by diffusing a p-n junction into a single n-type liquid epitaxy growth. This growth includes a narrow high-resistivity layer introduced by the transient incorporation of deep acceptors. The negative resistance has been shown to be due to optical feedback between the emitting junction and the photosensitive high-resistivity region. External quantum efficiencies of 0.08% at 565 nm with a current density of 11 A cm−2 have been obtained from these devices when used in a true latching mode with a standing bias of 5 V and turn-on turn-off pulses of ±4 V.
Ga1−x Alx As superlattices profiled by Auger electron spectroscopy
Authors: Ludeke R. , Esaki L. , Chang L. L.
Published: January 2004

Superlattice structures made by molecular beam epitaxy are profiled by a combined technique of argon sputter etching and Auger electron spectroscopy. The superlattice, consisting of periodic layers of 50-Å GaAs and Ga1−xAlxAs, probably represents the structure with the shortest period ever made and analyzed in monocrystalline semiconductors. Also established is the dependence of the intensity ratio of aluminum to arsenic signals of Auger transitions on the aluminum composition in Ga1−xAlxAs.
Diode detection of information stored in electron-beam-addressed MOS structure
Authors: Ellis G. W. , Possin G. E. , Wilson R. H.
Published: January 2004

Charge stored in an insulating layer on a semiconductor can influence the field at the surface of the semiconductor and consequently control the surface recombination velocity. This paper describes the use of this effect to control the current in a reverse-biased p-n junction in the semiconductor. When an electron beam is used to write and read the stored charge, the effect can be used to produce high-resolution high-gain devices that have a variety of potential uses in information-storage applications. Experiments demonstrating this effect are described.
Infrared up-conversion with resonantly two-photon pumped metal vapors
Authors: Bloom D. M. , Yardley James T. , Young J. F. , Harris S. E.
Published: January 2004

We report efficient up-conversion of low-level ir radiation near 10 μ to the near ultraviolet. Radiation at 9.26 μ is converted to 3305 Å with a photon conversion efficiency of 58% and a corresponding power gain of 16.2. The process employs resonant two-photon pumping of the nonallowed 3s-3d transition in Na.
Electrical characteristics of Al-implanted ZnSe
Authors: Shin B. K. , Park Y. S. , Look D. C.
Published: January 2004

Aluminum was implanted in ZnSe at 90 keV to a dose of 1015 ions/cm2 at room temperature. Hall-effect and sheet-resistivity measurements were made on the samples for various annealing conditions. The implanted layer is found to be degenerate n-type having a sheet resistivity of ∼103 Ω/□, after annealing at 900°C for 4 h.
Monolithic acoustoelectric amplifier using pseudosurface waves
Authors: Henaff Jeannine , Feldmann Michel , Le Contellec Michel
Published: January 2004

A small-signal differential gain as large as 100 dB/kV and a net gain of 20 dB have been observed at 160 MHz on Y+41°-cut X-propagation LiNbO3 material coated with an InSb thin film. Experimental results and tentative interpretation are presented.
Low-frequency piezoelectric-transducer applications of ZnO film
Authors: Shiosaki Tadashi , Kawabata Akira
Published: January 2004

It is revealed that a high-resistivity ZnO film highly oriented with the c axis perpendicular to a metal substrate surface can be used as a low-frequency piezoelectric transducer which generates and detects compressional strain or stress perpendicular to the c axis, i.e., perpendicular to the film thickness through the piezoelectric tensor component e311 or d311. For example, tuning-bar filters and a flat tuning-fork filter are successfully composed of ZnO films and Elinvar-alloy substrates whose resonant outputs are obtained even at frequencies lower than 100 kHz, and a piezoelectric microphone is composed of a ZnO film and a Ti membrane substrate.
Thermally stimulated field emission from pyroelectric LiNbO3
Authors: Rosenblum B. , Bräunlich P. , Carrico J. P.
Published: January 2004

Proximity-imaging techniques are used to observe thermally stimulated field emission (TSFE) from single-domain and multidomain single crystals of LiNbO3. Experimental results are reported and the mechanism responsible for this emission is discussed.
Generation of intense pulsed ion beams
Authors: Humphries S. , Lee J. J. , Sudan R. N.
Published: January 2004

An electrostatic vacuum triode is described in which it is possible to efficiently produce intense ion beams in the energy range around 100 keV for short times (∼50 nsec). In experiments to date, results have shown excellent agreement with predicted behavior. Equivalent proton currents of almost 500 A have been obtained at a peak energy in excess of 100 keV. The triode can easily be adapted to existing electron beam facilities.
Equations governing threshold switching in amorphous semiconductors
Authors: Walsh P. J. , Vezzoli G. C.
Published: January 2004

Extensive data are collected and presented to test the coupled-carrier equations and attending density-switching criterion proposed to describe nonthermal threshold switching in amorphous semiconductors. The equations and switching criterion predict in magnitude and functional form a wide range of phenomena found in the off-state, during the switching-on, in the on-state, and during the switching-off of amorphous chalcogenide films. The critical temperature noted in a variety of experiments is identified as the elevated temperature at which the switching criterion is fulfilled thermally in the presence of a small field.
Monolithic integrated InxGa1−xAs Schottky-barrier waveguide photodetector
Authors: Stillman G. E. , Wolfe C. M. , Melngailis I.
Published: January 2004

InxGa1−xAs Schottky-barrier diodes for detection in the 0.9–1.06-μm wavelength range have been incorporated in high-purity GaAs planar waveguides using a selective epitaxial growth process. A quantum efficiency of 60% at 1.06 μm has been obtained for these detectors, and current gain has been observed.
Optical waveguiding in graded-index layers
Authors: Conwell E.
Published: January 2004

We use the wave equation and WKB approximate solutions to study the general properties of modes in a waveguide whose index of refraction decreases monotonically with distance below its surface, due to variation of either ionic or electronic contributions. The modes are found to have oscillations that increase in amplitude and in spacing with increasing depth. For modes with smaller propagation constants the oscillatory regions, as well as the decaying regions, are found to penetrate more deeply.
Optical waveguides in barium sodium niobate
Authors: Hopkins M. M. , Miller A.
Published: January 2004

The introduction of hydrogen into single crystals of barium sodium niobate, which occurs during the usual poling procedure, causes refractive-index changes that permit the propagation of optical guided waves. Propagation of TM modes can be achieved even when the boundary between the hydrogenated and unhydrogenated region of the crystal is remote from the crystal faces. For thin hydrogenated layers, both TE and TM modes can be propagated. Phase-matched frequency doubling of the cw output of a Nd–YAG laser was demonstrated in such a layer.
Bistability behavior of texture in cholesteric liquid crystals in an electric field
Authors: Greubel W.
Published: January 2004

With the homeotropic boundary condition, the field-induced cholesteric-to-nematic texture transition can show a large hysteresis effect such that at the same field strength either the cholesteric or the nematic texture is stable.
Tunneling through thin MOS structures: Dependence on energy (E-κ)
Authors: Maserjian J. , Petersson G. P.
Published: January 2004

The tunneling characteristics of Cr/SiO2/Si structures in the thickness range 23–34 Å are reported. The E-κ dependence in the energy range extending 3.5 eV below the oxide conduction band is determined by the thickness dependence to be approximately of the Franz form with an effective mass ratio of 0.42. Tunneling into the indirect conduction band of silicon is reduced by a thickness-independent factor which decreases approximately exponentially with the energy below the direct band edge.
Radiation of difference frequencies produced by mixing in metal-barrier-metal diodes
Authors: Gustafson T. K. , Bridges T. J.
Published: January 2004

Millimeter radiation obtained by difference-frequency mixing of the P(20) and P(22) lines of the CO2 laser has been used to investigate the polarization, radiation pattern, and bias characteristics of metal-barrier-metal point-contact diodes. The results are consistent with antenna theory and the electron tunneling model of the point contact. Significant enhancement in performance is expected with eventual use as a submillimeter source.
Epitaxial growth over optical gratings on GaAs
Authors: Yang L. , Ballantyne J. M.
Published: January 2004

Epitaxial layers of GaAs have been successfully grown on corrugated GaAs substrates. Growth techniques were such that the corrugation was preserved during the growth process. Growth conditions are described which permit p-n junctions containing corrugations of period suitable for electrically pumped distributed-feedback lasers in GaAs to be produced. This work demonstrates that there are no fundamental limitations on growing buried corrugations in GaAs for a large variety of integrated optical devices.
Acoustic surface wave convolver with bidirectional amplification
Authors: Solie Leland P.
Published: January 2004

A surface wave convolver has been fabricated and tested with an interdigital structure which serves both as the output transducer for the convolution signal and as the biasing electrodes for bidirectional surface wave amplification of the two countertraveling input signals. The structure consists of a CdSe film on a Y Z LiNbO3 substrate with a delay path of 5 μsec. A convolution efficiency of −16 dB m has been obtained. Time reversal has been performed with the device.
Extinction technique for optical storage using anisotropic color centers in alkali halides
Authors: Schneider Irwin , Lehmann Matt , Bocker Richard
Published: January 2004

An extinction technique is described for obtaining high-contrast images while effectively increasing sensitivity in photodichroic alkali halide crystals.