bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface enrichment of In in evaporated Au–In films
Authors: Thomas Simon
Published: January 2004

The surface composition of evaporated Au(98%)–In(2%) alloy films has been investigated by Auger electron spectroscopy. Sputter etching showed the surface concentration to be markedly different from the bulk concentration. The In concentration on a freshly sputter-etched surface increases with time and reaches an equilibrium value of [inverted lazy s] 15 at.%, at room temperature. This In-enriched surface is believed to have the thermodynamically stable composition.
Laser emission at 1.065 μm from neodymium-doped anhydrous cerium trichloride at room temperature
Authors: Singh S. , Van Uitert L. G. , Potopowicz J. R. , Grodkiewicz W. H.
Published: January 2004

Room-temperature laser action is reported in Nd3+ : CeCl3. The observed threshold was 0.06 J compared to 0.13 J for Nd3+ : YAG. Stronger pump bands and higher laser transition cross sections of neodymium-doped anhydrous trichlorides of cerium and lanthanum render these materials superior to Nd3+ : YAG for miniaturized and thin-film laser applications.
Possible population inversions for VUV and soft x-ray transitions in hydrogenlike ions
Authors: Bohn Willy L.
Published: January 2004

Population inversions for optical transitions in the VUV and soft x-ray spectral region are predicted theoretically for decaying plasmas. The calculations are based upon a quasisteady-state theory for hydrogenlike ions. In contrast to other approaches it is shown that the characteristic relaxation time to generate inversions is not that of the corresponding upper levels but that of the ground state of the ions, i.e., the relaxation time for recombination. A plasmadynamic laser system for cw operation in the VUV is proposed.
Degradation mechanism of (Al · Ga)As double-heterostructure laser diodes
Authors: Yonezu H. , Sakuma I. , Kamejima T. , Ueno M. , Nishida K. , Nannichi Y. , Hayashi I.
Published: January 2004

This paper reports new observations in degraded (Al · Ga)As double-heterostructure (DH) laser diodes and proposes a mechanism of short-term ([inverted lazy s] 100 h) degradation characteristic to DH structures. Degradation is seen localized as ``dark lines'' of certain crystalline orientations in electroluminescent patterns, as well as junction current patterns using an SEM. X-ray measurement showed internal strain due to heteromismatch. It is suggested that the internal stress accelerates development of the dark lines, which is likely to be a crystalline defect caused by thermal stresses.
Optical intensity modulator with waveguide structure
Authors: Uehara S. , Yamauchi Y. , Izawa T.
Published: January 2004

A low-driving-voltage optical modulator with the configuration of an optical waveguide has been fabricated. A LiTaO3 single crystal with a thickness of 40 μm was used as the core and was cladded with a thin film of CeO2 formed by evaporation. The extinction ratio was better than 2%.
Coincidence of Er:YAG laser emission with methane absorption at 6077 cm−1
Authors: Fox Kenneth
Published: January 2004

This spectroscopic coincidence is considered from the viewpoint of experiments to measure tetrahedral parameters applicable to extensive calculations of atmospheric spectra. Theoretical results related to the polar character of the ground and excited vibrational states are discussed. Numerical values for ground-state transition frequencies, and estimates for ground- and excited-state Stark shifts, are given for the R (6) multiplet in 2ν3 of 12CH4. Possible applications are mentioned for 13CH4.
Effects of oxygen-reduction treatments on the threshold voltage and low-frequency noise of MOS transistors
Authors: Hielscher F. H. , End J. H.
Published: January 2004

A controlled series of MOS transistors have been studied to determine the effects of low-oxygen-partial-pressure atmospheres, resulting from high-temperature anneals in CO–CO2 gas mixtures, on the oxide charges and surface-state densities of the silicon-dioxide gates of MOS transistors, by measurements of threshold voltages and low-frequency 1/f noise. The results indicate that both the threshold voltage and the 1/f noise increase as the result of the reducing treatment, with noise increasing by more than two orders of magnitude. Partial reoxidation of reduced SiO2 decreased the threshold voltage, but did not decrease the noise level.
Interpretation of channeling effect measurements of disorder in ion-implanted silicon
Authors: Eisen F. H. , Bo/ttiger J.
Published: January 2004

A new method of applying channeling to determine the number of displaced atoms in an ion-implanted silicon sample is described. The technique utilizes measurements of the transmission energy spectra of channeled protons scattered 10° from the incident beam direction as they penetrate through thin ([inverted lazy s] 1 μm) silicon crystals to discriminate between ``true'' interstitial atoms and atoms only slightly off lattice sites due to strain. A comparison of this technique with the standard channeling effect technique, using backscattering, indicates that the channeling-backscattering technique is sensitive mainly to such ``true'' interstitial atoms.
Effect of oxygen on magnetization reversal of rare-earth-Co5 particles
Authors: Searle Clark W.
Published: January 2004

The nucleation field for rare-earth-Co5 particles is shown to be directly related to variations in the domain wall energy associated with an oxide layer at the particle's surface. A physical model based on the experimental results for Nd1−x Smx Co5 single crystals can quantitatively describe the magnetization reversal.
Current-carrying capacities of superconducting multifilamentary V3Ga cables
Authors: Furuto Y. , Suzuki T. , Tachikawa K. , Iwasa Y.
Published: January 2004

Current-carrying capacities at 4.2 K of superconducting multifilamentary V3Ga cables have been measured in transverse magnetic fields up to 20.8 T. The performance of the cables does not appear to be affected by bending as long as bending diameters are greater than 20 mm.
A spiral loaded low-β accelerating structure
Authors: Dick G. J. , Shepard Kenneth W.
Published: January 2004

This letter describes a new accelerating structure for a heavy-particle linear accelerator: a quarter-wavelength spiral loaded radio-frequency resonator. Experiments and preliminary analysis of this structure indicate that its performance as an accelerating structure is considerably superior to the helically loaded resonator in such important areas as surface electric field level, mechanical stability, and shunt impedance. As a superconducting device, a superconductiong lead-plated copper spiral resonator of phase velocity β = 0.045 has been run continuously at an accelerating field level of 1.46 MV/m with little degradation in Q below the low-field level. Measured properties of superconducting niobium imply that a niobium resonator of this type could reach accelerating fields in excess of 4 MV/m before reaching breakdown conditions.
Retrieval of electron-excited Auger structure by dynamic background subtraction
Authors: Houston J. E.
Published: January 2004

Electron-excited Auger electron spectroscopy normally relies on differentiation of the electron energy spectrum to enhance signal contrast. The contrast is increased, however, only at the expense of signal strength and the Auger structure itself is not recovered. Dynamic background subtraction, which involves multiple differentiation followed by integration of the same order, is shown to rectify these difficulties.
Schottky barrier InxGa1−xAs alloy avalanche photodiodes for 1.06 μm
Authors: Stillman G. E. , Wolfe C. M. , Foyt A. G. , Lindley W. T.
Published: January 2004

Uniform Schottky barrier avalanche photodiodes with gains greater than 250, rise times less than 200 psec, and good quantum efficiencies at 1.06 μm have been fabricated in InxGa1−xAs alloys. The material used for these devices was grown epitaxially on GaAs substrates using an AsCl3–H2–Ga–In vapor-phase system which permitted grading the epitaxial layers from GsAs to the desired composition.
Polarity-dependent electro-optical effect of nematic liquid crystals
Authors: Helfrich W.
Published: January 2004

A new type of flexoelectric realignment is predicted which has a threshold voltage and occurs for only one polarity. It requires the anchoring of the alignment to be of different strength on the two electrodes.
Comments on ``Effect of charge-transfer acceptors on dynamic scattering in a nematic liquid crystal''
Authors: Gaspard F. , Herino R.
Published: January 2004

Two recent papers describing the effects of charge-transfer acceptors on the electro-optical properties of a nematic liquid crystal are discussed on the basis of electrochemical considerations. A new interpretation is suggested which is consistent with the experimental facts.
Effect of deuteration on the ferroelectric transition temperature and the distribution coefficient of deuterium in K(H1−xDx)2PO4
Authors: Loiacono G. M. , Balascio J. F. , Osborne W.
Published: January 2004

The variation in the ferroelectric transition temperature with deuteration is described by a linear function only if the deuteration level in the crystal is considered. A least-squares fit of these data resulted in the relation Tc=121.7K + 1.07m, with m in mole% D. The effective distribution coefficient (keff) of deuterium in the system KH2PO4–KD2PO4–D2O was found to vary from 0.75 to 0.99 over the range of 25–99.8 mole% D.
Effects of poling conditions on responsivity and uniformity of polarization of PVF2 pyroelectric detectors
Authors: Day G. W. , Hamilton C. A. , Peterson R. L. , Phelan R. J. , Mullen L. O.
Published: January 2004

A large number of pyroelectric detectors, fabricated from commercially available PVF2 and poled under a variety of conditions of voltage, temperature, and time have been evaluated for responsivity and uniformity of polarization in the direction of the poling field. Results show that uniformity of polarization (a requirement for flat frequency response) can be achieved and responsivities as high as 2.9 μA/W can be obtained.
Trap ionization by electron impact in amorphous SiO2 films
Authors: DiMaria D. J. , Feigl F. J. , Butler S. R.
Published: January 2004

Electron impact ionization rates for an impurity-related electron trapping center in amorphous SiO2 films have been determined. These rates were obtained from analyses of trap population kinetics during uv-stimulated photocurrent injection. The dependence of the impact ionization rate αN on accelerating electric field E has been parameterized: αN = 25 exp(−1.5/E) cm−1, for E in MV/cm. This expression is the statistical average of results from three MOS specimens with a mean volume-averaged trapping state density N ≈5×1013 cm−3.
Effect of water and paint coatings on laser-irradiated targets
Authors: Fox Jay A.
Published: January 2004

Plexiglas and metal targets were illuminated in atmospheric air with a Q-switched neodymium : glass laser. Augmentation of the laser-induced stress waves was achieved with paint and water coatings. The spallation of Plexiglas and lead was observed. Measurements of the stress-time histories were taken with quartz stress gauges affixed to the rear surface of aluminum targets.
Measured radiation effects in MOS capacitors with a proposed new model
Authors: Holmstrom F. E. , Collins T. W. , Churchill J. N.
Published: January 2004

Flat-band shift measurements were made on p-type MOS devices irradiated with electrons at various gate bias voltages. A reproducible curve of flat-band shift versus gate bias was obtained that could not be readily accounted for with existing models. Data were taken over a wide range of negative and positive gate bias voltages. The model assumes that traps obey Fermi-Dirac statistics, subject to interface boundary constraints. A linearized quasi-Fermi level is assumed in the oxide. The resulting distribution of charged traps yields a self-consistent energy band structure throughout the entire device.
Pulse compression for more efficient operation of solid-state laser amplifier chains
Authors: Fisher Robert A. , Bischel W. K.
Published: January 2004

We propose a pulse compression scheme which reduces the peak intensity while increasing the energy density achievable in a Nd:glass amplifier chain. Self-focusing is the dominant effect responsible for limiting the power of a short-pulse Nd:glass amplifier chain, and the reduction of the intensity (through this compression scheme) greatly reduces these problems. We recommend injecting a lower-intensity and longer-duration pulse into the chain. Under some circumstances, the glass nonlinearity will impress upon the pulse a chirp suitable for efficient subsequent temporal compression, and this may result in higher effective peak power operation. If a 1-nsec (full 1/e duration) temporally Gaussian pulse with a chain-averaged peak intensity of 2 GW/cm2 propagates 2 m in a Nd:glass laser chain, we calculate that the pulse could be subsequently compressed (by a series of Gires-Tournois interferometers) to 125 psec with good stability against input pulse amplitude noise. Such short pulses are of major interest for laser fusion.
Current dependence of spontaneous carrier lifetimes in GaAs–Ga1-xAlx As double-heterostructure lasers
Authors: Namizaki H. , Kan H. , Ishii M. , Ito A.
Published: January 2004

The spontaneous lifetime of injected carriers in GaAs–Ga1-xAlx As double-heterostructure lasers is examined in relation to the current injection levels. It is shown that the spontaneous lifetime at threshold is proportional to Jth−1/2 in lasers with a 2×1017/cm3 Si-doped active region. From the proportionality constant the effective recombination constant Beff is estimated to be 9.0×10−11 cm3/sec, which agrees quite well with the theoretical value for band-to-band transitions.
126.1-nm molecular argon laser
Authors: Hughes William M. , Shannon John , Hunter Robert
Published: January 2004

Electron beam excitation of high-pressure argon has resulted in the first demonstration of laser action from molecular argon at 126.1±0.3 nm. Strong laser action was achieved at pressures up to 6.89 MPa (1000 psia).
Optical waveguides of single-crystal LiNbO3 film deposited by rf sputtering
Authors: Takada S. , Ohnishi M. , Hayakawa H. , Mikoshiba N.
Published: January 2004

A successful attempt in feeding a laser beam into a single-crystal LiNbO3 film deposited on a sapphire substrate by rf sputtering is described. The film thickness was 1800 Å. The loss of the film was less than 9 dB/cm at 6328 Å. The ordinary and extraordinary refractive indices of the film were no = 2.32±0.02 and ne = 2.18±0.04, respectively.
Nonequilibrium phenomena in ion-implanted MOS capacitors
Authors: Berger Josef
Published: January 2004

A new type of nonequilibrium capacitance-voltage characteristic was observed in a particular class of ion-implanted MOS capacitors. A model explaining these characteristics is proposed and a method to use them for evaluation of the implanted layers is suggested.
Manganese laser using manganese chloride as lasant
Authors: Chen Che Jen
Published: January 2004

A manganese vapor laser utilizing manganese chloride as a lasant has been observed and investigated. Lasing is attained by means of two consecutive electrical discharges. The maximum laser output is obtained at a vapor pressure of about 3 Torr, a temperature of 680°C, and a time delay between electrical discharges of 150 μsec. The maximum energy density is 1.3 μJ cm−3.
Optical waveguide modes in single-crystalline LiNbO3–LiTaO3 solid-solution films
Authors: Tien P. K. , Riva-Sanseverino S. , Martin R. J. , Ballman A. A. , Brown H.
Published: January 2004

We report new LiNbO3–LiTaO3 solid-solution films which form excellent active optical waveguides. Measurement of the waveguide modes indicates that these films have a graded composition. To analyze these waveguides, we present a theory for the calculation of the mode indices and find that the refractive index varies with the depth in the film, according to a Fermi function.
Effects of radiation on buried-channel CCDs with doped polysilicon gates and undoped polysilicon interelectrode isolation
Authors: Killiany J. M. , Saks N. S. , Baker W. D. , Barbe D. F.
Published: January 2004

The effects of gamma radiation on the operation of a buried-channel charge-coupled device having doped polysilicon electrodes and undoped polysilicon interelectrode isolation were studied. Doses up to 1×104 rad caused no increase in the transfer inefficiency. At a dose of 3×104 rad, the flat-band voltage shift was sufficient to drive the buried channel out of depletion and to cause field-induced channeling in the undoped polysilicon isolation regions. Increasing the channel bias returned the channel to depletion. However, channeling of the isolation regions could not be eliminated by changing the clock and bias voltages.
Conversion efficiencies of laser to x-ray energy in C, F, and Al plasmas
Authors: Whitney K. G. , Davis J.
Published: January 2004

A simple, but illustrative, nonhydrodynamic model is described which predicts potentially large conversion efficiencies of laser to x-ray energy in laser-heated plasmas. It is found that, when laser energy is deposited in 25 psec into the electron gas, a substantial conversion to x rays is possible in less than 1 nsec, provided the energy deposited per unit volume is not excessive. Moreover, while maximum K-line conversion increases with ion density, for a fixed electron critical density it decreases with increasing plasma Z.
Refractive index variations in proton-bombared fused silica
Authors: Presby H. M. , Brown W. L.
Published: January 2004

The variations in the refractive index of fused silica upon bombardment by protons are determined as a function of depth, in an optical fiber geometry, by techniques of interference microscopy. The index profiles clearly distinguish between the ionization and nuclear stopping regions, and the magnitude of the index change for both is presented as a function of incident flux. Significant differences in the dose dependence and the annealing properties of the two regions are found.
Observation of nuclear magnetic resonance from ion-implanted atoms
Authors: Weaver H. T. , Beezhold Wendland
Published: January 2004

Nuclear magnetic resonance (NMR) from ion-implanted atoms has been observed for the first time. 3He atoms were implanted at 70 °C into Pd thin films on both sides of a copper substrate. The NMR from the implanted 3He was detected using pulsed NMR techniques at 10, 20, and 35 MHz. Details of the ion implantation and NMR detection are described. Measurements of the 3He nuclear relaxation indicate that the implanted helium atoms are situated in small clusters within the Pd thin film.
Nonlinear interactions in guided Rayleigh waves
Authors: Coussot Gérard
Published: January 2004

The phase-matching condition for the second-harmonic generation of Rayleigh waves in a metallic guide structure on a piezoelectric substrate is determined. Experiments on a Y–Z LiNbO3 guide are investigated. The mode characteristics and the generation of the second harmonic are measured. An enhancement of the second-harmonic intensity is pointed out in the guide structure as compared with a free surface.
Yielding and grain-boundary ledges: Some comments on the Hall-Petch relation
Authors: Murr L. E.
Published: January 2004

Direct observations of grain-boundary ledges have been made in a number of metals and alloys by transmission electron microscopy. Grain-boundary ledges have been observed to be sources of dislocations, and emitted dislocations take on the appearance of pileups. It is suggested that, because of the dearth of observations of dislocation pileups, the pileup concept be reconsidered in the flow-stress-grain-size relationship, and conversely that serious consideration be given to the role of grain-boundary structure, particularly ledges, in determining the mechanical properties of metals and alloys.
Observation of field-induced microstructure in β phase of 8/65/35 PLZT electro - optic ceramics
Authors: Michel C. , Sicignano A.
Published: January 2004

A chemical etching technique has been found which reveals a complex microstructure in the field-induced β phase of lanthanum zirconate-titanate electro-optic ceramics having a composition 8/65/35. This microstructure in the electrically depoled state is irregular, while that in the electrically poled state is highly lamellar in character. Similar patterns were induced by mechanical strain. No evidence of microstructures was found in the thermally depoled α phase.
Excited-state absorption spectrum of cresyl violet perchlorate
Authors: Shah Jagdeep , Leheny R. F.
Published: January 2004

Measurements of excited singlet state absorption in the laser dye cresyl violet perchlorate (CVP) are described. The influence of this process on the efficiency of longitudinally pumped dye lasers can be significant and is discussed.
Characteristics of thinned backside-illuminated charge-coupled device imagers
Authors: Shortes S. R. , Chan W. W. , Rhines W. C. , Barton J. B. , Collins D. R.
Published: January 2004

A linear 500×1 charge-coupled device (CCD) surface channel imager is thinned to less than 30 μm, with the thinned back surface accumulated to reduce the surface recombination velocity. Photoresponsivity is measured to be 90 mA/W of incident wide-band power from a 2854-K blackbody light source. This sensitivity is a factor of 3 higher than previously reported values. Spectral responsivity reaches a peak of 90% quantum efficiency at 7000-Å wavelength, and over 50% quantum efficiency for the spectral range from 5000 to 9000 Å. A 32% square wave amplitude response at the Nyquist limit is obtained at a location 150 resolution elements from the output diode. Optical imager resolution obtained by using the backside-illuminated device is illustrated.
Direct current inductance bridge for current-quantum-phase measurements in superconductors
Authors: Meservey R. , Paraskevopoulos D. , Gruenberg L. W. , Tedrow P. M.
Published: January 2004

A zero-frequency inductance bridge has been constructed for measurement of the inductance of superconducting circuit elements. The null detector uses a quantum magnetometer. The bridge is balanced by resistance adjustments at room temperature and gives directly the inductance or the quantum phase difference versus the current across the unknown superconducting element. The bridge has been used to measure kinetic inductors with 4×10−7 H to one part in 104 with a measuring current of 5×10−6 A.
Suppression of hard bubbles in LPE garnet films by inert atmosphere annealing
Authors: LeCraw R. C. , Gyorgy E. M. , Wolfe R.
Published: January 2004

A new method for the suppression of hard bubbles in single-layer LPE garnet films has been developed. The method involves annealing the films in an inert atmosphere for a few hours at temperatures near 1100 °C. The proposed mechanism involves enhanced diffusion of Ga from the substrate into the film due to oxygen vacancies produced by annealing in the inert atmosphere. The diffused Ga replaces Fe on tetrahedral sites forming a thin second layer of reduced magnetization at the film-substrate interface. This new method may have advantages in convenience and cost over the available hard-bubble suppression techniques.
Application of least-squares (difference-integration) method to cumulants analysis in intensity fluctuation spectroscopy
Authors: Lee S. P. , Chu B.
Published: January 2004

A least-squares difference-integration method is described by which a sum or distribution of exponentials can be characterized using moments or cumulants analysis. Comparison of the higher-order approach with the procedures of Koppel using simulated data at realistic experimental signal-to-noise ratios shows definite improvements in the determination of those moments.
CO2 laser heating of a magnetized plasma column
Authors: Molen G. M. , Kristiansen M. , Hagler M. O. , Bengtson Roger D.
Published: January 2004

A 280-cm3 volume of a magnetized plasma column has been heated by a 15-J CO2 TEA laser. The 2-eV plasma with peak electron densities of 3×1016 cm−3 was axially irradiated by the collimated unfocused laser beam. A measured temperature increase of approximately 0.5 eV was found to be in excellent agreement with classical absorption by inverse bremsstrahlung. A significant increase in heating was observed using a multipass heating scheme.
Stability of optical levitation by radiation pressure
Authors: Ashkin A. , Dziedzic J. M.
Published: January 2004

Stable optical levitation of transparent hollow dielectric spheres has been demonstrated using TEM01 mode laser beams. The levitation of solid dielectric spheres has been made much more stable using highly convergent TEM00 mode beams. We have discovered the existence of two distinct stable regimes of levitation for solid spheres, one located above the beam focus, the other below it. A particle can be switched back and forth between these regimes. Three separate stable regimes are also possible.
Switching in organic polymer films
Authors: Henisch H. K. , Smith W. R.
Published: January 2004

Memory and threshold switching processes are described, as observed in systems consisting of thin (∼0.5 μ) polymer films (polymethylmethacrylate, polystyrene, polyethylmethacrylate, polybutylmethacrylate) between inert electrodes (graphite, molybdenum, NESA glass). The memory off-state is highly linear, in contrast to the corresponding characteristics of multicomponent chalcogenide glasses. Switching speeds are probably similar or, at any rate, ≪10−7 sec.
Resonant tunneling in semiconductor double barriers
Authors: Chang L. L. , Esaki L. , Tsu R.
Published: January 2004

Resonant tunneling of electrons has been observed in double-barrier structures having a thin GaAs sandwiched between two GaAlas barriers. The resonance manifests itself as peaks or humps in the tunneling current at voltages near the quasistationary states of the potential well. The structures have been fabricated by molecular beam epitaxy which produces extremely smooth films and interfaces.
Effect of doping on degradation of GaAs–Alx Ga1−xAs injection lasers
Authors: McMullin P. G. , Blum J. , Shih K. K. , Smith A. W. , Woolhouse G. R.
Published: January 2004

The influence of the active layer dopant on the degradation of GaAs–Alx Ga1−xAs double-heterostructure lasers has been studied using pulsed excitation. Compensated p -type dopants give the slowest degradation, while n -type dopants give the most rapid. These results can be understood on the basis of arsenic vacancy migration and the formation of arsenic vacancy-acceptor complexes.
Possibility of a distributed-feedback x-ray laser
Authors: Fisher Robert A.
Published: January 2004

It is suggested that distributed feedback might greatly improve the chances of achieving x-ray laser action in a crystalline material. We have considered the case where the cavity mirror structure is provided by internal Bragg scattering which is distributed throughout the lasing medium. In addition to providing efficient feedback, higher effective gains can be achieved by eliminating the influence of periodic absorbers which occur in selectively x-ray-pumped polyatomic crystals. This is accomplished by establishing a standing wave with its nulls on the periodically spaced absorbers.
Holography with off-axis reference beam derived from the object beam
Authors: Som S. C. , Lessard R. A.
Published: January 2004

Holograms of two- and three-dimensional objects can be taken without a separate reference beam. Two methods are discussed, the first one for two-dimensional objects and the other for three-dimensional ones. Experimental arrangements and image quality are discussed and supporting results are given.
Nd-glass laser with three-dimensional optical waveguide
Authors: Saruwatari Masatoshi , Izawa Tatsuo
Published: January 2004

Room-temperature laser operation in a three-dimensional Nd-glass waveguide is reported. The waveguide was fabricated by a double-diffusion process with ion migration. A Nd-glass laser, 4 mm in length, was end-pumped at 590-nm wavelength with a pulsed Rhodamine 6G dye laser. The threshold power for the Nd-glass waveguide laser was about 18 μJ, which was nearly one-half of that for a conventional Nd-glass laser without guiding structure. The measured value of the threshold for a waveguide laser agrees with the theoretical calculation.
High gain at 10.6 μm from an electron-beam-controlled pulsed discharge
Authors: Carmichael C. H. H. , Garnsworthy R. K. , Mathias L. E. S.
Published: January 2004

The production of high gain at a wavelength of 10.6 μm in CO2–N2 gas mixtures at pressures up to 300 kPa (3 atm) has been demonstrated using brief ionizing pulses from a gas-discharge electron gun and a low-inductance circuit to supply energy to the gas mixture. Increased gain, up to 10 m−1, has been achieved with mixtures containing H2.
Two-step excitation of fluorescence in iodine monochloride vapor
Authors: Barnes R. H. , Moeller C. E. , Kircher J. F. , Verber C. M.
Published: January 2004

Two-step sequential excitation of fluorescence was produced in ICl vapor using two synchronized tunable laser sources. The pumping scheme involved the E←A←X electronic transitions with subsequent E→A transitions being observed in fluorescence.
Pulsed HF chemical laser linewidth measurements using time-resolved bleachable absorption of HF gas
Authors: Peterson L. M. , Arnold C. B. , Lindquist G. H.
Published: January 2004

The spectral linewidth at 2.7 μ of a transverse discharge pulsed HF chemical laser has been measured using the saturable absorption of low-pressure HF gas in an external cell. Using the ν = 0 to ν = 1 P(J) transitions, the laser linewidth was found to be 10−4 cm−1—120 times narrower than the Doppler spectral width. Heterodyne beating between two HF lasers was observed and the pulse-to-pulse frequency shift noted.
Negative ion lasers
Authors: Golden David E. , Ormonde Stephan
Published: January 2004

The principle of detailed balance is used to show that at a maximum in an electron excitation cross section, due to a very-short-lived negative ion resonance (10−14–10−16 sec), the electron deexcitation cross section can be significantly smaller than the electron excitation cross section. Using experimental estimates of the various necessary parameters, it is suggested that population inversion may be maintained or enhanced in pure gas lasers by electron bombardment at negative ion resonance energies.
Application of holographic interferometry to shock waves in solids
Authors: Perry F. C. , Mix L. P.
Published: January 2004

Double-pulse holographic interferometry has been used to determine the rear-surface displacement of a target exposed to a pulsed electron beam. The technique has been applied to the study of shock-wave propagation in a complex heterogeneous material—three-dimensional quartz phenolic. The results suggest a multiple-wave character for shock propagation in this material.
Ion-implanted GaAs injection laser
Authors: Barnoski M. K. , Hunsperger R. G. , Lee A.
Published: January 2004

Ion implantation has been used as a doping technique to fabricate an injection laser in GaAs. The dopant atom is Zn. At 77 °K the threshold current density is 2×103 A/cm2.
cw dye laser emission spanning the visible spectrum
Authors: Yarborough J. M.
Published: January 2004

cw dye laser emission over the entire spectral range from 4150 to 7900 Å has been achieved in a single dye laser. Experimental results using eighteen dyes, including several for which cw operation has not been previously reported, are presented.
An experimental study of the linear growth region of ultrashort-pulse generation in a mode-locked Nd : glass laser
Authors: Sam C. L.
Published: January 2004

An experiment is performed to measure τ1, the duration of the linear growth stage of ultrashort-pulse (USP) generation, in a mode-locked Nd : glass laser. A linear relationship between USP pulsewidth and τ1 is derived and borne out experimentally. From the linear gradient τ1 is estimated to be about 100 μsec. Some precursor spikes are observed in most shots and might account for the long τ1.
Epitaxial PbSe Schottky-barrier diodes for infrared detection
Authors: Hohnke D. K. , Holloway H.
Published: January 2004

The photovoltaic properties and infrared response of epitaxial PbSe Schottky-barrier diodes are reported. The temperature dependence of the zero-bias resistance suggests that generation/recombination is the dominant transport mechanism. At 77 °K the devices are limited by the 290 °K background at f/0.6. With further reduction of the background they attain Johnson-noise-limited peak detectivities of 5×1011 cm Hz1/2 W−1. The diode quantum efficiencies are reflection loss limited and reach 70%.
Calculations of apparent conductivity for an anisotropic medium: (TTF) (TCNQ)
Authors: Warmack R. J. , Callcott T. A. , Schweinler H. C.
Published: January 2004

Calculations are presented for determining the potential at an arbitrary point in an anisotropic two-dimensional rectangular conductor for arbitrary placement of current source and sink. Using values of experimentally determined conductivities of (TTF) (TCNQ), apparent longitudinal conductivities are calculated to try to explain the anomalously high conductivity peak reported for a few samples of (TTF) (TCNQ). We conclude that the temperature dependence of these high conductivity peaks cannot be produced by probe misplacement using ordinary samples.
Alignment mechanism in twisted nematic layers
Authors: Dixon G. D. , Brody T. P. , Hester W. A.
Published: January 2004

Twisted nematic displays have been constructed in areas up to 36 square inches. Alignment of the liquid crystals was achieved by the oblique evaporation of silicon monoxide or gold. The surface deposits were examined by electron microscopy which indicated that mechanical alignment occurred due to the presence of islands and holes on the surface. It was found that the contrast ratio of the display decreased as the evaporating angle decreased.
Bilinear signal processing using acoustic surface waves
Authors: Feldmann Michel , Henaff Jeannine
Published: January 2004

Nonlinear interactions between noncollinear ASW with exact phase matching provide a special kind of convolution and correlation, according to the ratio ω1/ω2 of the input frequencies. It means that the time scale at the output port depending on this ratio, time compression or expansion can be achieved. The same device can be used for both correlation and convolution with equal NL conversion efficiency.
Mechanism of fast surface flashover in vacuum
Authors: Anderson R. A.
Published: January 2004

Insulator samples of Plexiglas and alumina ceramic in vacuum have been subjected to high-voltage pulses with rise times of a few nanoseconds. Breakdown paths were inclined to the electric field in the presence of a magnetic field normal to the insulator surface, analogous to the Hall effect for bulk conduction. These results, as well as measurements of the flashover propagation velocity, strongly support a model of the flashover mechanism based on secondary electron emission.
Neutron emission from a small 1-kJ plasma focus
Authors: Michel L. , Schönbach K. H. , Fischer Heinz
Published: January 2004

Neutron emissions from a small 0.34–1.35-kJ (10–20-kV) plasma focus in D2 ranged between 1.2×106 and 2.8×108 neutrons per shot. Shapes of the neutron and the hard x-ray pulses (half-width [sine wave] 50 ns) agree, coinciding in time with the ``dip'' in the di/dt pulse. The angular neutron emission appears to follow the assumptions of the target beam model. Optical filament structures in the 30-ns-duration focus could not be observed.
Propagation of x rays in waveguides
Authors: Spiller Eberhard , Segmüller Armin
Published: January 2004

Waveguide structures and couplers for x rays are analyzed. Experimental results are given for the propagation of Cu Ka radiation in guides made of BN.
Refractive index of AlxGa1−xAs between 1.2 and 1.8 eV
Authors: Casey H. C. , Sell D. D. , Panish M. B.
Published: January 2004

The refractive indices of AlxGa1−xAs samples prepared by liquid-phase epitaxy were determined from accurate double-beam reflectance measurements. The variation of the refractive index with photon energy at room temperature was obtained for AlAs mole fractions between 0 ≤ x ≤ 0.38 in the spectral range 1.2–1.8 eV.
Optical filter using a vapor mirror
Authors: Senitzky Benjamin
Published: January 2004

The characteristics of a mercury vapor filter based on the principle of selective specular reflection are described. The filter passband is in the region of 2536.5 Å and its bandwidth can be varied from 0.1 to 1 Å by changing the vapor pressure. The device is used in an atomic emission flame photometer. A photograph of the distribution of Hg* in the flame is also obtained.
Submillimeter detection and mixing using Schottky diodes
Authors: Fetterman H. R. , Clifton B. J. , Tannenwald P. E. , Parker C. D.
Published: January 2004

Schottky diodes have been used for the first time as harmonic mixers in the 0.1–1.0-mm wavelength region. Beat notes between the 33rd harmonic of a 74-GHz V-band klystron and 118.8-μ laser radiation are observed directly without the need of narrow-band synchronous detection. The demonstrated performance of these room-temperature diodes as wide-band or heterodyne detectors of submillimeter radiation and their rugged construction make them superior to current point contact devices.
Photolocking-A new technique for fabricating optical waveguide circuits
Authors: Chandross E. A. , Pryde C. A. , Tomlinson W. J. , Weber H. P.
Published: January 2004

Low-loss dielectric optical waveguides have been made by a new process in which a photochemical reaction is used to lock or fix a dopant in a polymer film with a lower refractive index, and unreacted dopant is then removed by heating. Narrow guides ([inverted lazy s]4 μm wide, Δn [inverted lazy s] 1%) were formed by laser beam writing at λ=364 nm or by contact printing at λ=313 nm, and had losses of 0.20±0.05 dB/cm at λ=633 nm.
Metal oxide varistor-A multijunction thin-film device
Authors: Levinson Lionel M. , Philipp H. R.
Published: January 2004

The physical origin of the highly nonlinear current-voltage relation in metal oxide varistors is shown to be consistent with Fowler-Nordheim tunneling.
Composition dependences of the energy gap and the green-band emission peak for the AlxGa1−xP ternary system
Authors: Sonomura H. , Nanmori T. , Miyauchi T.
Published: January 2004

The AlxGa1−xP alloys having compositions up to x = 0.74 are prepared by slow cooling from Ga-rich Al–Ga–P solutions. The composition of the alloy is accuratley determined from the density measured by using the flotation method. The alloy composition almost corresponds to the atomic ratio of Al to P in the initial mixture. The energy gap and the green-band emission peak of the alloy vary linearly to the higher-energy side as the Al concentration increases.
Silicon as a residual donor in high-purity GaAs
Authors: Wolfe C. M. , Korn D. M. , Stillman G. E.
Published: January 2004

The question regarding the role of silicon as a residual impurity in high-purity GaAs is resolved by the use of careful doping experiments and high-resolution far-infrared spectroscopy. The results indicate that silicon is readily incorporated into the material as a simple substitutional donor with a binding energy of 5.854 meV and show that silicon is a major, but not necessarily the dominant, residual donor in high-purity vapor and liquid epitaxial GaAs.
Room-temperature laser operation of InxGa1−xAs p-n junctions
Authors: Nuese C. J. , Enstrom R. E. , Ettenberg M.
Published: January 2004

Room-temperature laser diodes which emit coherent infrared radiation near 1.1 μm have been prepared from InxGa1−xAs (x [inverted lazy s]0.23) vapor-grown p-n junction structures. At 77°K, laser threshold current densities as low as 1210 A/cm2 and external differential quantum efficiencies as high as 50% have been obtained at 1.08 μm. At 300°K, the threshold current densities are between 70 000 and 98 000 A/cm2 for emission at 1.145 μm.
A limitation for nanosecond CO2 pulse amplification
Authors: Pan Y. L. , Simpson J. R. , Bernhardt A. F.
Published: January 2004

We have determined experimentally a limitation for nanosecond CO2 pulse amplification at atmospheric pressure in 5:1:1 He:CO2:N2 gas mixtures. We find that the refraction effect, self-defocusing, will present difficulties both in the amplification of a nanosecond CO2 laser pulse to substantial energies and in subsequent laser fusion experiments where the laser beam is to be focused onto a target.
Gain saturation and self-focusing considerations in the design of optical amplifiers
Authors: Elliott C. James
Published: January 2004

We extend the stability analysis of the quasioptical equation given by Bespalov and Talanov and by Suydam to the case of Frantz-Nodvik pulse propagation. When ε ≈ (An0g0/2 π λ)2 ≪ 1, we find that the logarithm of the perturbation growth divided by the input intensity depends on the input illuminance and the media gain. This relationship is important in amplifier design. The asymptotic growth may be given in closed form even when ε ≫ 1. This form is used for design refinements when indicated by an a posteriori estimate.
Trapping and absorption of an axially directed CO2 laser beam by a θ-pinch plasma
Authors: Amherd Noel A. , Vlases George C.
Published: January 2004

A deuterium-filled θ pinch was axially irradiated in the first half-cycle by a CO2 laser to demonstrate the effects of beam trapping and absorption by a plasma. Peak electron densities were 5×1016 cm−3 and the nonirradiated axial temperature was about 1.3 eV. Detection of the laser radiation transmitted through the plasma showed that beam trapping occurred when the density profile had a minimum on axis, and the maximum laser-induced temperature increase of 2 eV occurred for irradiation at the time of maximum density, in agreement with inverse bremsstrahlung predictions. Furthermore, the plasma emission histories indicated that the column underwent a laser-induced elongation of up to twice its original length.
Application of an organic dye for wavefront multiplication
Authors: Sawatari T. , Shupe D. M.
Published: January 2004

An application of a dye solution for wavefront multiplication is described. In this application, two coherent pumping laser beams generate a spatial gain and index-of-refraction distribution in a dye amplifier. This distribution is used to modulate the amplitude and phase of an optical field in the amplification band of the dye in order to form a new wavefront. To establish that the multiplication is due to singlet-state effects and not to triplet-state excitation, the lifetime of the information in the dye cell is measured.
Observation of magnetic domains in nickel using the scanning electron microscope
Authors: Newbury D. E. , Yakowitz H. , Yew N. C.
Published: January 2004

Scanning electron microscope (SEM) observation of magnetic domains in a polycrystalline pure nickel sheet was made possible through the use of a 50-kV accelerating potential. The contrast was unobservable in an SEM capable of only a 30-kV accelerating potential.
Stoichiometry of thin silicon oxide layers on silicon
Authors: Sigmon T. W. , Chu W. K. , Lugujjo E. , Mayer J. W.
Published: January 2004

The composition of anodically and thermally grown silicon oxide layers was determined by backscattering and channeling measurements with 2.0-MeV 4He+ ions. The oxide thickness was determined by ellipsometry and, for anodic films, the silicon removal rate was also determined by layer removal measurements. The surface layer consists of stoichiometric silicon dioxide plus a silicon-rich transition layer between the substrate and the silicon dioxide. The number of silicon atoms in this layer was found to be 6 × 1015 atoms/cm2 (about three atomic layers).
Optoacoustic properties of thallium phosphorous selenide, Tl3PSe4
Authors: Isaacs T. J. , Gottlieb M. , Feichtner J. D.
Published: January 2004

A new material, Tl3PSe4, has been grown as a single crystal and studied for its optical and optoacoustic properties. It is transparent over the range 0.85–17 μm and has an optoacoustic figure of merit (relative to fused silica) of 1370 (at 1.15 μm). The slow shear wave acoustic velocity is 5.1×104 cm/sec, the lowest recorded in the literature for a solid or a liquid. The low velocity and high refractive index (n ≈ 3) lead to the high figure of merit.
Energy transport efficiency of an intense relativistic electron beam through a cusped magnetic field
Authors: Kapetanakos C. A.
Published: January 2004

A 500-keV 40-kA 50-nsec-duration relativistic electron beam is propagated through a cusped magnetic field. Conditions are reported which allow more than 85% of the beam energy to pass through the cusp.
Observation of hydrodynamic effects on thermal blooming
Authors: O'Neil R. W. , Kleiman H. , Lowder J. E.
Published: January 2004

We have observed thermal blooming of focused 10.6-μ laser radiation in the transient regime where the index changes are dominated by the hydrodynamic response of the medium. In this regime (where the time is less than one-half of the hydrodynamic time in the focal plane) it is seen that the approximation wherein the refractive index is proportional to t3 gives an adequate agreement with the experimental observations.
Compact 1.1-W sealed-off waveguide CO laser
Authors: Asawa Charles K.
Published: January 2004

cw output of 1.1 W was attained from a compact (14-cm discharge length, 2-mm bore diameter tube) sealed-off CO waveguide laser operating in the HE11 mode. The BeO laser tube, cooled to 210 °K, was operated at the 1-W level for more than 4 h without output degradation and with a 5.7% efficiency. A mixture of CO:He:Xe:N2 in the ratio of 1:8:1:1, at a total pressure of 80 Torr, was found to be optimum, confirming the scaling or similarity rule of the product of optimum pressure and tube diameter for CO at this temperature. The output spectrum consisted of about 10 lines, between 5.20 and 5.65 μ. Laser operation without N2 (1:8:1:0) was also observed. Black particles found in the tube were x-ray identified as Ni plus NiO, indicating sputtering from the Ni cathode.
Resonance reflector for suppressing undesired rotational lines from TEA CO2 lasers
Authors: Röhr H. , Kellerer L.
Published: January 2004

A resonant reflector made of germanium is reported which allows selection of one single rotational line out of a TEA CO2 laser. The reflector has to be temperature stabilized within ± 0.1 °C. Selection of one, two or three rotational lines simultaneously is possible by varying the temperature.
6190-Å emission at 77 K of Ga1−xAlxAs double heterostructure lasers
Authors: Itoh Kunio
Published: January 2004

The Ga1−xAlxAs laser diodes which emit a wavelength of 6190 Å at 77 K with threshold current densities as low as 300 A/cm2 were fabricated using a double heterostructure with lightly doped active regions. This lasing wavelength is the shortest ever attained in Ga1−xAlxAs lasers for such a low threshold current density. The maximum external quantum efficiency of these diodes was found to be about 35% at 77 K. The extensive studies made of the properties of these visible-light-emitting lasers, especially of the spectral distributions, are described in full detail.
Volume holographic recording and storage in Fe-doped LiNbO3 using optical pulses
Authors: Shah Pradeep , Rabson T. A. , Tittel F. K. , Gaylord T. K.
Published: January 2004

Volume holographic recording and storage in Fe-doped LiNbO3 using single 30–75-nsec duration optical pulses at 694.3 and 531 nm from Q-switched ruby and frequency-doubled Nd:glass lasers, respectively, is reported. The recording sensitivity for a pulsed writing source is found to be better than that estimated for a cw source. A sensitivity of 2 mJ/cm2 at 476 nm and 2.5 mJ/cm2 at 488 nm to record a hologram of 1% diffraction efficiency is the best sensitivity figure yet reported. The orders of magnitude of improvement in sensitivity is attributed to higher fractional concentration of Fe2+.