bluuebunny/crossref_metadata_2025 huggingface dataset:
Lasing Transitions in p+-n-n+ (AlGa) As–Ga As Heterojunction Lasers
Authors: Kressel H. , Lockwood H. F.
Published: January 2004

A study of the lasing and spontaneous emission from p+-n-n+ heterojunction lasers with lightly doped n-type active regions shows that the stimulated emission is not due to a simple band-to-band recombination process. It is further shown that the 300 K gain coefficient dependence on the junction current differs greatly from that predicted on the basis of band-to-band lasing involving a parabolic density-of-states distribution.
Defining the ``Random'' Spectrum as Used in the Channeling Technique of Nuclear Backscattering
Authors: Ziegler J. F. , Crowder B. L.
Published: January 2004

A new method is described for operationally defining a ``random'' spectrum as used in channeling studies of nuclear backscattering. The method is reproducible to 1%. A detailed analysis is made for the case of He4 ions backscattered from silicon crystals. Corrections are determined so the ``random'' spectrum approximates that from an amorphous layer to within ± 1%.
Polarized Raman Studies of Anisotropic RbClO3 Crystals by the Immersion Technique
Authors: Hwang D. M. , Solin S. A.
Published: January 2004

Artificial depolarization and anisotropy induced broadening of the Raman spectra recorded in air from small RbClO3 single crystals of extremely poor optical quality can be effectively eliminated by immersion of the sample in an index-matching fluid. Measurement temperatures as low as − 110°C have been obtained using a commercial cryostat fitted with a specially designed sample support system.
Optically Pumped Volume-Excited cw Room-Temperature In1−x Gax P (x ≤ 0.60) Platelet Lasers
Authors: Scifres D. R. , Holonyak N. , Macksey H. M. , Dupuis R. D.
Published: January 2004

Room-temperature cw laser operation well into the visible spectrum (λ ∼ 6000 Å) is reported for In1−xGaxP (x ≤ 0.60). Thin (1–5-μ) experimental samples are compressed into In, under a thick (∼ 250-μ) high-index (η > 2. 6) SiC window, with a thin (10–50-μ) narrow SiC platelet under part of the In1−xGaxP sample. The thin In1−xGaxP samples, in the compound cavity, are volume excited in a small spot with an argon laser so that the heat is easily removed by the SiC windows and nearby In heat sink.
Critical Velocity and Mass of Domain Walls in Thin Magnetic Films
Authors: Schlömann Ernst
Published: January 2004

The structure of moving domain walls in thin films having a uniaxial anisotropy axis in the plane of the film is calculated by a variational method. The calculation applies for wall velocities ν smaller than a critical velocity at which the derivative of the wall energy with respect to ν becomes infinite. At intermediate film thicknesses the critical velocity is much smaller, the effective wall mass (per unit area) much larger than for bulk crystals and/or very thin films.
Luminescence from LiNbO3
Authors: Hordvik A. , Schlossberg H.
Published: January 2004

LiNbO3 has been found to emit strong luminescence when irradiated by a ruby laser beam. The luminescence varies linearly with input power, is broad band, independent of crystal orientation, and decreases exponentially with the inverse absolute temperature, as does the luminescence decay time. The effect is closely related to so-called ``optical index damage'', and provides a new means for studying that phenomenon.
ZnSe Electroluminescent Device Exhibiting Switching and Memory
Authors: Livingstone A. W. , Allen J. W.
Published: January 2004

An MIS structure, in which the semiconductor is suitably doped ZnSe, exhibits switching and memory properties. The same structure also emits light in both forward and reverse bias with an emission wavelength characteristic of the impurities present. Although the operation of the device is not completely understood the switching can be attributed to a transfer of charge from deep impurities in the semiconductor to the insulating layer.
Optical Measurement of Surface-Wave Scatter Losses in Piezoelectric Ceramics
Authors: DeVries Adrian J. , Miller Robert L.
Published: January 2004

Direct experimental measurement of surface-wave scatter losses of several ceramics is reported, as well as verification of the fourth-power frequency dependence of scatter losses per wavelength predicted by Steg and Klemens. Laser measurements of surface-wave amplitude vs position exhibit interference due to scattered waves. The statistical analysis of such measurements allows separation of scatter losses from true dissipative losses. Scatter losses for Honeywell Type S material are found to be 0.027 dB/wavelength at 46.8 MHz, and increase with the fourth power of frequency. A limiting frequency for a given ceramic for surface-wave applications might be the frequency at which scatter losses overtake dissipative losses; for Honeywell S, this occurs at 73 MHz.
Embossed Optical Waveguides
Authors: Ulrich R. , Weber H. P. , Chandross E. A. , Tomlinson W. J. , Franke E. A.
Published: January 2004

Dielectric optical waveguides have been made by embossing grooves in a thermoplastic substrate and filling them with a liquid which is then solidified. Grooves (7 μm wide and 3.5 μm deep) in poly(methyl methacrylate) (n=1.49) were filled with cyclohexyl methacrylate which was photopolymerized to produce a permanent guide (n=1.505). The attenuation was 2–4 dB/cm at λ=0.633 μm.
Microwave Measurement of the Velocity-Field Characteristic of n-Type InP
Authors: Glover G. H.
Published: January 2004

Measurements of the velocity-electric field characteristic of n-type InP at 9.5 and 35 GHz are reported. The results indicate a peak velocity of about 2.7×107 cm/sec and threshold field of 12 kV/cm. The measurements are in good agreement with a two-valley model of conduction.
Polariton Results in Ferroelectrics with the Tungsten Bronze Crystal Structure
Authors: Burns Gerald
Published: January 2004

Measurements are presented as a function of temperature, in several ferroelectric crystals with the tungsten bronze crystal structure, using forward Raman scattering (polaritons). These results determine the frequencies of TO and LO modes. Thus, the strengths of the optic modes and the frequency dependence of the dielectric constant ε(ω) can be determined. From these results, the low-frequency clamped dielectric constant ε(0) surprisingly is found to be approximately independent of temperature to Tc. We believe that the results indicate that these ferroelectrics do not have ``soft'' optic modes in the usual sense but are relaxers.
Behavior of a Deionized Liquid Crystal Subjected to Unipolar Injection in Nematic and Isotropic Phase
Authors: Lacroix Jean-Claude , Tobazéon Robert
Published: January 2004

Electrohydrodynamic phenomena in insulating MBBA subjected to unipolar injection of ionic carriers are described. Near the transition temperature, the transient currents following a voltage step were similar in the nematic and isotropic phases, over a wide range of voltages and electrode separations. High-speed cinematography, Schlieren techniques, and the Kerr effect were resorted to in this investigation. Liquid motion was observed having a time lag and exhibited patterns closely similar to those previously observed in isotropic polar liquids. The velocities of hydrodynamic disturbances and of space-charge fronts varied over a broad range, depending on experimental conditions.
High-Field Transport Properties of CdTe
Authors: Ruch J. G.
Published: January 2004

A Monte Carlo calculation has been used to calculate the high-field transport properties of CdTe where the full complexity of the band structure has been taken into account. Comparison with experimental results yields basic transport parameters, e.g., deformation potential for nonequivalent intervalley scattering.
Fast-Interface-State Losses in Charge-Coupled Devices
Authors: Carnes J. E. , Kosonocky W. F.
Published: January 2004

A simple model which predicts the large signal losses in charge-coupled devices due to fast-interface-state trapping is presented, and the predictions of the model are verified by experimental measurements of losses in two-phase CCD's.
Operation of a Ruby Laser in the Purely Transverse Electric Mode TE01
Authors: Pohl Dieter
Published: January 2004

A ruby laser has been operated in the circular TE01 mode by means of a novel mode selector. Construction, output characteristics, conversion into TM01, and possible applications are described.
Nonlinear Susceptibility of GaP; Relative Measurement and Use of Measured Values to Determine a Better Absolute Value
Authors: Levine B. F. , Bethea C. G.
Published: January 2004

We have measured the ratio d36(GaP)/d11(SiO2) = 185 ± 10% at 1.318 μ. By using this value together with other values in the literature, we determine a better set of absolute values for the nonlinear susceptibility.
Acoustic-Surface-Wave Isolator
Authors: Lewis M. F. , Patterson E.
Published: January 2004

A 200-MHz acoustic-surface-wave isolator has been constructed employing an epitaxial layer of Ga-doped YIG on a gadolinium gallium garnet substrate.
Broadband Efficient Excitation of the Thin-Ribbon Waveguide for Surface Acoustic Waves
Authors: Yen K. H. , Li R. C. M.
Published: January 2004

A practical method for broadband efficient excitation of the thin-ribbon waveguide for surface acoustic waves is presented. Other major advantages of the excitation system are the simplicity of both its theoretical design and its practical implementation. Experimentally, a maximum excitation efficiency (power) of 65% has been obtained at an operating frequency of 5.5 MHz. In addition, the measured efficiency was in excess of 55% over the frequency range from 4.7 to 6.4 MHz.
Uniformly Polarized GaAs Laser Array
Authors: Wieder Harold , Marinace John C.
Published: January 2004

A structure is described which yields uniform polarization in the emitted light from an array of GaAs lasers. The exterior cleaved faces define a standard Fabry-Perot structure, and a 2-μ air space within the cavity inclined at the Brewster angle provides the necessary discrimination in gain between orthogonal modes to produce TE polarization (within ± 3°) for all lasers in the array.
Green Electroluminescence in ZnSe–ZnTe Heterojunctions by Liquid-Phase Epitaxial Growth
Authors: Fujita Shigeo , Arai Seiichi , Itoh Kunio , Moriai Fumi , Sakaguchi Tadao
Published: January 2004

ZnSe–ZnTe heterojunctions prepared by liquid-phase epitaxial growth method exhibited green electroluminescence with the peak of about 5350 Å at 77°K. The photoluminescence at 77°K from uv excitation was also measured and it was found that the green emission seems to result from hole rather than electron injection.
Distortion of the Central Resonance in Long Interdigital Transducers
Authors: Daniel M. R. , Emtage P. R.
Published: January 2004

Experiments are reported showing that the central resonance in long uniform interdigital transducers is distorted and the bandwidth reduced. These phenomena are shown to result from back-piezoelectric effects.
Fast CO2-Laser Modulation by Hot Carriers
Authors: Müller K. -H. , Nimtz G. , Selders M.
Published: January 2004

Experiments carried out with n-germanium have shown that hot carriers modulate the transmission of the radiation of CO2 lasers. The modulation is very fast and theoretically limited only by the relaxation time of the carriers, which is of the order of 10−12 sec.
Surface Motion Measurements on Surface Elastic Waves
Authors: Lawrence M. W. , Davies L. W.
Published: January 2004

The motion in the sagittal plane described by surface particles due to passage of a surface elastic wave has been accurately measured in Y-cut X-propagating quartz. The motion was found to be retrograde elliptical with the major axis normal to the crystal surface. The ratio of longitudinal to transverse axes is 0.672 ± 0.005, a value in very good agreement with theory.
Preparation and Detection of Large Coherent Optical Polarizations in Resonant Media
Authors: Nurmikko A. V. , Schwarz S. E.
Published: January 2004

An unusually orderly excited state of a degenerate resonant molecular system occurs when all the resonant molecules are polarized in the same phase. The largest obtainable optical polarization of the medium is obtained under such conditions. Here we describe a technique by which such a maximally orderly excited state may be approached. Adiabatic fast half-passage is used. Neither a tunable laser nor a tunable resonant medium is required, and disorder is not introduced by local intensity variations or degeneracy of the resonant levels. Nearly complete polarization of the available molecules has been measured by means of a phase-switching technique.
Uniform Direct-Current Discharges in Atmospheric Pressure He/N2/CO2 Mixtures Using Gas Additives
Authors: Schriever R. L.
Published: January 2004

Uniform direct-current discharges in atmospheric-pressure mixtures of He/N2/CO2 have been achieved by the use of an organic gas additive. Best results were obtained using xylene as an additive with a concentration of 0. 5% in a 90/5/5 gas mixture. Observed current densities were limited by external circuitry, but uniform pulsed discharges with current densities over 3 A/cm2 were obtained when the dc discharge was pulsed.
Investigation of a 1-J Pulsed Discharge-Initiated HF Laser
Authors: Pummer H. , Kompa K. L.
Published: January 2004

A pulsed hydrogen fluoride chemical laser is described whose maximum energy and power is 1.2 J and 3 MW. Details of the experimental setup are given and spectrum measurements for various SF6H2 pressures are reported. The results indicate that under these conditions rotational levels with J> 10 are substantially pumped.
Growth Kinetics Observed in the Formation of Metal Silicides on Silicon
Authors: Bower R. W. , Mayer J. W.
Published: January 2004

Backscattering of MeV He ions has been used to investigate the composition and growth kinetics of metal silicides formed from thin films of Pd, Ti, Cr, and Mo evaporated onto Si. In each system studied, one silicide phase predominated (Pd2Si, TiSi2, CrSi2, and MoSi2). The thickness of the phase increased with (time)0.5 for Pd2Si and TiSi2, and linearly in time for CrSi2 and MoSi2. It was found that these two time dependencies correlate directly with the reaction sensitivity to a thin oxide interface (<100 Å) and to the extent of the silicide formation in the neighborhood of a typical device contact region.
Magnetoelastic Rayleigh-Type Surface Wave on a Tangentially Magnetized YIG Substrate
Authors: Parekh J. P. , Bertoni H. L.
Published: January 2004

The propagation characteristics of an exchange-free magnetoelastic Rayleigh-type surface wave propagating on a YIG substrate in the direction of a tangentially applied bias field are treated. The surface wave is found to be of the leaky-wave variety within a band of frequencies given approximately by the magnetostatic bulk-wave spectrum, rather than of the bound surface-wave variety occurring outside this frequency band.
Ferroelectric Optical Rotation Domains in Single-Crystal Pb5 Ge3 O11
Authors: Dougherty J. P. , Sawaguchi E. , Cross L. E.
Published: January 2004

Well-defined 180° ferroelectric domains of hexagonal shape with reversible optical rotary power are observable in Pb5Ge3O11 with nicols off the crossed position; sharp domain walls appear with crossed nicols. The switching time is given by tα(E − E0)−α, where E0≈3 kV/cm and α ≈ 1.5.
Low-Loss Reflection Coatings Using Absorbing Materials
Authors: Spiller Eberhard
Published: January 2004

A new design principle is described which allows construction of mirrors that are of reasonable reflectivity (R>25%) in the extreme ultraviolet (λ = 50 to 500 Å). The measured performance of a first mirror for the near uv using this design principle is given.
Novel Technique for Real-Time Depth-Gated Acoustic Image Holography
Authors: Whitman R. L. , Korpel A. , Ahmed M.
Published: January 2004

An acoustic camera, which uses a scanning laser beam to detect an ultrasonic image, has been modified to incorporate the desirable depth-discrimination feature characteristic of pulse-echo techniques. The resultant system combines the virtues of acoustic holography with those of the pulse-echo method. It produces a real-time image hologram of a 2.268-MHz acoustic field with the transverse resolution characteristic of imaging (approximately three wavelengths or 2 mm), and the depth resolution of the pulse-echo technique (1–10 mm depending on the acoustic pulse length). The pulsing and gating action of the system prevents (1) image degradation due to too many out-of-focus cross sections, typical in imaging systems, and (2) most of the multiple reflection artifacts, typical in pulse-echo systems. Moreover, average acoustic power requirements for signal-to-noise considerations are lowered from the cw case by the pulse-duty factor.
Generation of a surface-acoustic-wave correlation echo from coupling to charge carriers
Authors: Gunshor R.L. , Lee C.W.
Published: January 2004

A forward-propagating surface-acoustic-wave signal interacts with a pump field applied to a nearby semiconductor. The result is the generation of a backward-propagating ``echo'' whose envelope is the correlation of the signal and the pump. The echo is 25 dB down from signal for the pump power used.
Optically pumped atmospheric-pressure CO2 laser
Authors: Chang T.Y. , Wood O.R.
Published: January 2004

Laser action at 10.6 μm has been obtained in pure CO2 gas at pressures up to 1 atm by optically pumping with the 4.23μm line of a TEA HBr laser. The potential usefulness of this method for pumping very high density CO2 is discussed.
Rapid cooling by laser melt quenching
Authors: Elliott W.A. , Gagliano F.P. , Krauss G.
Published: January 2004

Laser melt quenching has been used to obtain high cooling rates comparable to those obtained by ``splat cooling'' techniques. By measurements of dendrite spacing, the average cooling rate in a laser-melted aluminum alloy was determined to be 3.7×106°C/sec. Laser melt quenching applied to a Ag–Cu alloy suppressed the two-phase equilibrium eutectic structure and resulted in the formation of a single-phase solid solution.
rf augmentation in CO2 closed-cycle dc electric-discharge convection lasers
Authors: Eckbreth Alan C. , Davis Jack W.
Published: January 2004

dc electrical power deposition in CO2 closed-cycle electric-discharge convection lasers (EDCL) can be increased to levels characteristic of open-cycle performance by the application of rf (13.7-MHz) auxiliary power. Experiments have been conducted with the radio frequency capacitively coupled into the discharge zone transverse to the dc field through the top and bottom walls of a rectangular laser channel. The effect of rf power on the dc power level and on the small-signal gain coefficient is described.
High-speed photography of laser-induced breakdown in liquids
Authors: Lauterborn W.
Published: January 2004

A giant pulse of a ruby laser is focused into water, silicone oils, and some other liquids. High-speed photography of the focal region with picture repetition rates up to 850 000 pps shows the dynamics of the produced bubbles. These are extremely well suited to study cavitation bubble dynamics. Spherical almost empty bubbles can be produced in water, realizing the Rayleigh bubble model. The shock wave produced by the laser-induced breakdown is made visible by small bubbles suspended in the vicinity. From the radial motion of these bubbles, conclusions can be drawn on the strength of the shock wave.
X-ray diffraction study of single crystals undergoing shock-wave compression
Authors: Johnson Quintin , Mitchell Arthur C. , Evans L.
Published: January 2004

Single crystals of LiF, Al, and graphite have been studied by x-ray diffraction while undergoing shock-wave compression to about 300 kbar. These studies show that single crystals can transform to the hydrostatically compressed state essentially as single crystals, and crystal orientation is preserved.
Time-resolved differential holographic microscopy
Authors: Presby H.M.
Published: January 2004

The methods of holographic interferometry have been applied to the study of dynamic phenomena on a microscopic scale. The developed system has a spatial resolution in the 10-μ range and a temporal resolution in the submicrosecond regime.
Acousto-optical effect in photochromics and its applications
Authors: Iizuka Keigo
Published: January 2004

It was found that the color fading rate of a photochromic film is accelerated when it is exposed to an acoustic field. The investigation of the effect was made with acoustic waves both in water and in air. This newly found effect was utilized as a novel means of mapping an acoustic field. It was shown that the effect can be used to map not only acoustic waves in a liquid, but also acoustic waves generated on the surface of an ADP (ammonium dihydrogen phosphate) crystal. In addition, an acoustic hologram of a small object in water was recorded using this effect.
Damping of domain wall motion in rare-earth iron garnets
Authors: Vella-Coleiro G.P. , Smith D.H. , Van Uitert L.G.
Published: January 2004

Landau-Lifshitz damping parameters deduced from domain wall mobility measurements are reported for a number of rare-earth iron garnets. These damping parameters are compared with the ones obtained from ferrimagnetic resonance experiments.
Observation of laser oscillation in pure rotational transitions of OH and OD free radicals
Authors: Ducas T.W. , Geoffrion L.D. , Osgood R.M. , Javan A.
Published: January 2004

The first observation is reported of laser oscillation in pure rotational transitions of the OH and OD free radicals. 44 lines in OH and 17 lines in OD have been seen in the 12- to 20-μ region. Transitions were observed within the v=0, 1, 2 vibrational levels of OH and the v=0 vibrational level of OD. Accurate values are calculated for the B and D rotational constants for OD and higher-order rotational constants for OH.
Large quiescent collisionless high-frequency discharge plasma
Authors: Ault Earl R. , MacKenzie K.R.
Published: January 2004

200 V p-p (peak to peak) at 80 MHz applied to a plane sheet electrode of 0.0075-cm-diam parallel wires produces a reasonably uniform large-volume collisionless plasma in zero magnetic field with a density of ∼ 109 ions/cm3 in argon at 3 × 10−4 Torr. The noise fluctuation level 〈δn/n〉 ≃ 2 × 10−4.
Infrared-microwave double resonance of NH3 in the presence of a high-field Stark effect
Authors: Fourrier M. , Redon M.
Published: January 2004

Exact coincidences between infrared vibration-rotation transitions of NH3 and CO2 or N2O laser lines have been obtained using high-field Stark effect. Different schemes of pumping have been used, giving either increase or decrease of microwave absorption.
Mode-locked high-pressure waveguide CO2 laser
Authors: Smith P.W. , Bridges T.J. , Burkhardt E.G. , Wood O.R.
Published: January 2004

Active mode locking of a high-pressure cw waveguide CO2 laser is reported. Pulse widths as short as 3 nsec are obtained. The results are shown to be in good agreement with existing theory.
Closed-cycle performance of a high-power electric-discharge laser
Authors: Brown Clyde O. , Davis Jack W.
Published: January 2004

The performance characteristics of a large-volume CO2 electric-discharge convection laser operating in a closed-cycle mode are described. The use of a combined dc and rf excitation field and aerodynamic stabilization techniques resulted in the attainment of a stable and homogeneous discharge. Operating in a master oscillator-power amplifier mode, continuous-output power levels greater than 20 kW have been achieved for extended periods of time, with a maximum optical power of 27.2 kW at an efficiency of 17.2%.
Electric-field-induced transient spin-flip Raman laser pulses in InSb
Authors: Mooradian A. , Brueck S.R.J. , Johnson E.J. , Rossi J.A.
Published: January 2004

An InSb spin-flip Raman laser pumped continously by a carbon monoxide laser near 5.2 μm has produced Stokes pulses of ≲ 10−9-sec duration when an electric field of a few V/cm was applied or removed from the sample. This effect is interpreted in terms of a transient Raman gain, which occurs when electrons are heated or allowed to cool in the conduction band.
Elastic and piezoelectric constants of the cuprous halides
Authors: Hanson R.C. , Hallberg J.R. , Schwab C.
Published: January 2004

Elastic and piezoelectric constants of CuCl, CuBr, and CuI have been measured. The elastic constants of zinc-blende-structure materials when plotted on a reduced scale indicate a striking instability as the Phillips critical ionicity (0. 785) is approached. CuCl is the most piezoelectric of these materials with a piezoelectric constant e14=0.41 C/m2 at 80°K.
Observation of Fresnel fringes in the conventional scanning electron microscope
Authors: Broers A.N.
Published: January 2004

Images of Fresnel fringes have been obtained in the conventional surface scanning electron microscope operating in the transmission mode. These fringes provide a means for critically evaluating instrument resolution, final lens astigmatism, and source brightness.
Correlation of fractional-monolayer oxygen determinations obtained by proton-excited x-ray and Auger electron spectroscopy analysis of Fe surfaces
Authors: Needham P.B. , Driscoll T.J. , Rao N.G.
Published: January 2004

Oxygen Kα x rays excited by the impact of 120-keV protons have been used to determine absolute oxygen surface coverages ranging from 4.8×1014 to 5.2×1015 atoms/cm2 on polycrystalline iron samples mounted in an Auger spectroscopy system. Amplitudes of the electron-beam-excited oxygen KL2L2 Auger electron spectra obtained from the samples corresponded linearly with the coverages determined by the proton-excited x rays (PEX). Estimates of the oxygen adatom coverages using the Auger results and the theoretical approach of Bishop and Riviere were found to agree within a factor of 2.15 (± 0.22) with the PEX-determined coverages.
cw operation and nitric oxide spectroscopy using diode lasers of Pb1−xGex Te
Authors: Antcliffe G.A. , Parker S.G. , Bate R.T.
Published: January 2004

cw operation at liquid-helium temperatures of junction lasers fabricated from the IV-VI alloy Pb1−xGexTe is reported. These lasers are current tunable and emit in the infrared between 4 and 6 μm. Preliminary high-resolution spectra of nitric oxide recorded near 5.3 μm by using these lasers are reported.
Guided-wave propagation at 10.6 μm in silver bromide thin films
Authors: McFee J.H. , McGee J.D. , Chang T.Y. , Nguyen V.T.
Published: January 2004

A germanium prism coupler has been used to couple a CO2 laser beam into thin AgBr films deposited on NaCl substrates. Thermographic phosphor screens and an infrared scanner were used to detect guided-wave propagation in the films. Measurement of the TE0 and TM0 coupling angles yielded the film index (2.14) and thicknesses. The latter were in excellent agreement with independent thickness measurements.
Carbon monoxide chemical laser from the reaction O + Cse → CO† + Se
Authors: Wittig Curt , Smith Ian W.M.
Published: January 2004

Laser emission from vibrationally excited CO (CO†) has been observed when mixtures of CSe2, O2, and He are partially dissociated by a pulsed electric discharge. Observations on the spontaneous emission confirm that the CO† is formed in the reaction O + CSe → CO†+Se, which is 118 kcal/mole exothermic and produces CO selectively in high vibrational levels. A comparison is made with the analogous system O + CS → CO†+S.
Stimulated Brillouin scattering in optical fibers
Authors: Ippen E.P. , Stolen R.H.
Published: January 2004

Observations of backward stimulated Brillouin scattering (SBS) in glass optical fibers are reported. Threshold for SBS has been achieved with less than 1 W of input power at 5355 Å. Relaxation behavior in the SBS signal has also been observed and is attributed to finite-cell-length oscillation. Experimental results are compared with theory, and the implied limitation to optical fiber transmission is discussed.
Observation of the transparency of a resonant medium to zero-degree optical pulses
Authors: Grieneisen H.P. , Goldhar J. , Kurnit N.A. , Javan A. , Schlossberg H.R.
Published: January 2004

Experiments are described in which low-intensity laser pulses of zero area [∫−∞∞E(z,t) dt=0] are propagated through a degenerate resonantly absorbing medium with greatly reduced absorption. These pulses are constructed either electro-optically or by allowing a non-zero-degree pulse to evolve toward zero area by means of a resonant absorption and reradiation process. We observe the transmission of as much as 65% of the energy of such pulses through a resonant absorber which attenuates the same cw laser by e−αL, with αL ≈ 20.
Optimum focusing conditions for parametric gain in crystals with double refraction
Authors: Kuizenga D.J.
Published: January 2004

In a uniaxial crystal, walk-off or double refraction occurs only in the plane of the direction of propagation and the optic axis. By elliptical focusing of the signal, idler, and pump we can focus much more tightly in the non-walk-off plane and increase parametric gain considerably. Optimum focusing conditions are obtained, and in a typical LiNbO3 oscillator pumped with 1.06 μ we find that threshold can be lowered more than a factor of 5.
Electronic superposition of sample current and secondary-electron images in Auger electron spectroscopy
Authors: Morabito J.M. , Munro D.F.
Published: January 2004

Selected-area analysis by Auger electron spectroscopy requires a knowledge of electron-beam location and the ability to place the beam on specified areas quickly and reproducibly. For samples with both conducting and insulating regions, it is highly desirable to use a grazing-angle-of-incidence electron beam to reduce surface-charging effects. Unfortunately, the use of grazing incidence makes the location of the area of interest and simultaneous optimization of the Auger signal rather difficult because of a parallax problem. Superposition of sample current images and secondary-electron images produced by scanning the electron beam from the grazing-incidence gun provides a solution to these alignment problems.
Mode losses in hollow-waveguide lasers
Authors: Chester Arthur N. , Abrams Richard L.
Published: January 2004

We have developed a theory to solve for the lowest-order mode of hollow dielectric laser resonators with external mirrors. The results agree well with previously reported experimental results. In general, the optimum position (or positions) for a mirror of fixed curvature can be calculated, but as yet no simple rule has been found for predicting these positions.
Light-intensity modulation in CdS film
Authors: Honda Masanori , Fujimori Masatoshi , Nishimura Yasuro
Published: January 2004

An investigation was made of the influence of an electric field on the transmission of a multilayered structure consisting of CdS and glass films. The same shift of the fundamental absorption edge was observed with the application of an electric field of 10–50 V to the sample as for a single crystal with a high applied voltage of about 1000 V. We also obtained a large-modulation degree at longer wavelengths of 0.55–1.4 μ than at the wavelength of the fundamental absorption edge of CdS and obtained light-intensity modulation of the He–Ne laser at 6328 Å.
Enhancement of self-focusing threshold in sapphire with elliptical beams
Authors: Giuliano C.R. , Marburger J.H. , Yariv A.
Published: January 2004

The power threshold for optically induced bulk damage in sapphire is a sensitive function of the ellipticity of the incident beam shape. Experimental results are consistent with a simple self-focusing theory.
Observation of the inverse Lamb dip for infrared-microwave two-photon transitions
Authors: Freund S.M. , Oka T.
Published: January 2004

An inverse Lamb dip has been observed for infrared-microwave two-photon transitions in 14NH3 and 15NH3. The signal was sufficiently strong to be observed on an oscilloscope with a detector time constant of 3 msec. The observations establish a method of measuring differences between laser frequencies and molecular absorption frequencies with high accuracy even if this absorption is outside of the tuning range of the laser lines. A double resonance experiment involving the two-photon inverse Lamb dip has also been conducted.
Growth mechanism of polycrystalline β-SiC layers on silicon substrate
Authors: Graul J. , Wagner E.
Published: January 2004

The surface of monocrystalline silicon was chemically converted with hydrocarbon to polycrystalline β-silicon carbide, and the growth mechanism was investigated by means of 14C tracer method. It is shown that the growth of the silicon carbide layer is due to diffusion of silicon through the SiC layer so that the Si–SiC conversion is taking place at the surface of the sample. Dependence of layer thickness on carbidizing time and on hydrocarbon concentration in the carrier gas hydrogen was measured.
Importance of nozzle geometry to high-pressure gas-dynamic lasers
Authors: Kuehn Donald M.
Published: January 2004

A CO2 gas-dynamic laser (GDL) was operated over a range of reservoir pressures and temperatures, test-gas mixtures, and nozzle geometries. A significant result is the dominant influence of nozzle geometry on laser power at high pressure. Results show that high reservoir pressure can be effectively utilized if nozzle geometry is chosen to efficiently freeze the test gas. Maximum power density with the least efficient nozzle was 3.3 W/cm3 of optical cavity volume, whereas 83.3 W/cm3 was attained with the most efficient nozzle.
Behavior of spontaneous emission across threshold in GaAs junction lasers
Authors: Ripper J.E. , Patel Navin B. , Brosson P.
Published: January 2004

The spontaneous emission behavior of a cw stripe-geometry GaAs laser is examined in detail. Contrary to recently published results, a sharp discontinuity of the spontaneous emission growth occurs when the laser reaches threshold. Above threshold, slow increases in the spontaneous emission are observed, coming mostly from the regions where the lasing light intensity is small. Other discontinuity points were, at higher currents, observed corresponding to the onset of higher-order modes and second-order mode locking.
Prism-dye laser
Authors: Chandra S. , Takeuchi N. , Hartmann S.R.
Published: January 2004

A simple continuously tunable laser-pumped dye laser is described. A dye solution in contact with a lateral face of a right-triangular 90° prism, adjacent to the 90° corner, is pumped by laser light incident on the lateral face opposite to the 90° corner. A standing-wave pump field is produced in the dye solution by the interference between the pump light that passes directly to the inner face in contact with the dye solution and the pump light internally reflected from the other lateral face adjacent to the 90° corner. The output wave-length is determined by the spatial periodicity of the standing-wave field and is easily varied by changing the angle of incidence between the pump-laser beam and the prism face.
Interacting Bloch lines: a new mechanism for wall energy in bubble domain materials
Authors: Malozemoff A.P.
Published: January 2004

The energy of an isolated vertical Bloch line in high-Q bubble materials is only a small fraction of the total wall energy. However, if there are so many Bloch lines along a domain wall that they are constrained to lie close to each other, their exchange energy becomes large. Calculations including this energy show qualitative agreement with the anomalous dependence of dimensions on bias field in certain bubbles and stripes in garnet films.
Determination of TN for KNiF3 through elastic, magneto-optical, and heat capacity measurements
Authors: Nouet J. , Zarembowitch A. , Pisarev R. V. , Ferre J. , Lecomte M.
Published: January 2004

Ultrasonic resonance, stress-induced linear dichroism, and heat capacity measurements are used in an accurate determination of the Néel temperature of the cubic antiferromagnet KNiF3. All three techniques give a value of 246 ± 1°K for TN.
Observations of Zeeman effect in the optical spectra of fast ion beams
Authors: Stoner John O. , Radziemski Leon J.
Published: January 2004

We have observed splittings between the σ+ and σ− groups of components of optical lines emitted by fast beams of Ar+ and O+ [v/c = (3.2−4.2) × 10−3] in a magnetic field of 13 800 G. In order to observe these separations, which were of the order of 0.2–0.3 Å, it was necessary to reduce the recorded widths of spectral lines by refocusing the spectrometer and by exciting the beam in a gas target.
Gunn effect threshold and domain formation in transverse magnetic fields in indium antimonide
Authors: Heinrich H. , Keeler W.
Published: January 2004

The potential has been probed on n-type InSb bar samples at nanosecond time scales, both with and without an applied magnetic field. In a transverse magnetic field, nucleation of a traveling domain occurs at the side of the cathode where the electric field is high due to Hall field shorting. The results explain the strong reduction of Gunn effect threshold in a magnetic field.
Catastrophic disruption of the flow of a magnetically confined intense relativistic electron beam
Authors: Friedman M. , Hammer D.A.
Published: January 2004

A disruption in the flow of an intense annular relativistic electron beam occurred when a sudden change in the radius of the drift tube walls was introduced. Experimental results showed that the electron beam (which was immersed in a homogeneous magnetic field) was under the influence of a strong nonadiabatic force which caused considerable changes in beam characteristics, such as spatial distribution and electron transverse energy.
Discovery of anomalous base regions in transistors
Authors: Ziegler J.F. , Cole G.W. , Baglin J.E.E.
Published: January 2004

The theoretical description of transistors has been impeded by the lack of knowledge of the p-type impurity distributions. A method is described which accurately gives concentration profiles of the boron p-type regions in transistors. The technique has been used to establish that the base regions in the fastest bipolar transistors are markedly different than usually assumed.
A-15 structure Mo–Re superconductor
Authors: Gavaler J.R. , Janocko M.A. , Jones C.K.
Published: January 2004

An investigation of the properties of Mo–Re thin films has been undertaken. Superconducting transition temperatures of up to ∼15°K have been observed in films which have an approximate composition of Mo0.7Re0.3. This increase in Tc of 2–3°K over the corresponding bulk values is attributed to the formation of a metastable A-15 phase in the sputtered films of this composition.
Singly resonant CdSe infrared parametric oscillator
Authors: Herbst R.L. , Byer R.L.
Published: January 2004

We have demonstrated an infrared singly resonant parametric oscillator using CdSe as the nonlinear crystal. The oscillator operates with either a resonant signal near 2.2 μ or resonant idler in the 9.8- to 10.4-μ region. Using a Q-switched Nd : YAG laser operating at 1.833 μ as a pump source, we have observed thresholds of 550 W and up to 40% conversion efficiency. The angle-tuned oscillator operates at room temperature with a 2-cm−1 bandwidth.
Photoconductivity and luminescence in lanthanum oxysulfide
Authors: Dobrov W.I. , Buchanan R.A.
Published: January 2004

Rare-earth doped crystals of lanthanum oxysulfide were found to exhibit strong photoconductivity which increases rapidly with temperature. Correlation of photoconductivity to luminescence spectra of La2O2S : Eu shows that thermal quenching of the luminous emission from 5D states leads to the production of photocarriers, the majority of which are most likely holes. Special features of La2O2S : Eu photoconductivity indicate the important role which the charge-transfer states play in the luminescence mechanisms.
Optical waveguides of single-crystal garnet films
Authors: Tien P.K. , Martin R.J. , Blank S.L. , Wemple S.H. , Varnerin L.J.
Published: January 2004

We report light-wave propagation experiments in single-crystal epitaxially grown garnet films. The discussion includes refractive index and lattice constant considerations for various garnets, and also the use of iron garnet films on gallium garnet substrates as magneto-optical waveguides useful in integrated optics.
Forced-convective-flow carbon monoxide laser
Authors: Kan Tehmau , Whitney Wayne
Published: January 2004

Forced convective flow has been applied to a CO laser, resulting in an order-of-magnitude enhancement of the output power density over what can be achieved from the same laser under diffusion-dominated operation. A 1-m-long 2.5-cm-diam-bore laser has produced 400 W of cw emission at 20% electrical efficiency.
Magnetic-field-enhanced heating of plasmas with CO2 lasers
Authors: Cohn Daniel R. , Lax Benjamin
Published: January 2004

The effect of high magnetic fields upon the heating rate of CO2-laser-produced plasmas has been calculated. It is found that the inhibition of thermal losses in the presence of high magnetic fields should substantially enhance the effectiveness of the CO2 laser as a means of creating hot plasmas. Electron and ion temperatures are computed for plasmas produced with 1010-W CO2 lasers.
Transient oscillator analysis of a high-pressure electrically excited CO laser
Authors: Lacina W.B. , Mann M.M.
Published: January 2004

A molecular kinetic model and self-consistent oscillator analysis have been developed for electrically excited transient and steady-state (CO, N2, He, Ar, …) laser systems. Theoretical calculations for a transient oscillator are compared with experimental data obtained from a high-pressure electron-beam-stabilized long-pulse transverse-discharge CO device.
Twisted domain wall structure in bubble films
Authors: Schlömann Ernst
Published: January 2004

Because of the magnetic surface charge, the wall magnetization is ``twisted'' into a direction almost perpendicular to the wall plane near the film surface. The width and energy of such walls and the twist angle have been calculated by a variational method for uniaxial anisotropy and stationary plane walls. For very thick films (film thickness ≫ wall width in an infinite medium), the reciprocal wall width and the wall energy are smaller than the values for an untwisted wall by approximately a factor (1 − 0. 65σ)½, where σ=4πM0/Ha, M0 being the saturation magnetization and Ha the uniaxial anisotropy field.
Condenser-transducer array for acoustical holography
Authors: Nigam A.K. , Sessler G.M.
Published: January 2004

An electroacoustic transducer array employing condenser-microphone elements with a solid dielectric diaphragm is described. Both diaphragm and backplate of the array are selectively metallized on one side along parallel strips and positioned so that the metal strips of the diaphragm are perpendicular to the metal strips of the backplate with the dielectric foil separating the two. The areas of overlapping diaphragm and backplate strips form identical condenser microphone elements. The array is mechanically and electrically simple, is capable of operation in gases and liquids over wide frequency ranges, and can be designed with large apertures. The overlapping metal-strip technique can also be employed for piezo-electric arrays.
Electrical characteristics of vitreous vs common carbons
Authors: Kaufman Alvin B.
Published: January 2004

The carbonization of certain cross-linked polymers under carefully controlled conditions yields a nongraphitizing carbon which, on account of its high lustre and conchoidal fracture, has been called ``vitreous carbon''. The temperature coefficient of resistivity for this carbon has been determined and its bulk resistivity reconfirmed. These are compared to carbons formed from other bases, and it is shown that, although vitreous carbon has unique mechanical properties, its electrical characteristics are similar to a common form of processed carbon.
ac-dc technique for rapid conical-helical perturbation in cholesteric liquid crystals
Authors: Oron N. , Labes M.M.
Published: January 2004

Two stages in the relaxation process for conical-helical perturbation in cholesteric liquid crystals are seen when a dc electric field is applied. The second stage, which is accompanied by the growth of optical rotation with time, is relatively long. By replacing the dc field with a 30- to 60-Hz ac field, this long relaxation stage can be eliminated and the total relaxation time is shortened. However, this also causes the response time to become longer, as compared to the response to a dc field. A four-electrode cell and an ac-dc combined technique is described by which both advantages of rapid response and relaxation times are achieved.
Arc-excited flowing CO chemical laser
Authors: Boedeker Laurence R. , Shirley John A. , Bronfin Barry R.
Published: January 2004

Application of thermal dissociation of O2, developed within arc-heated gas mixtures, followed by a sufficiently rapid convection to preserve O atom concentrations and subsequent CS2 injection, has generated efficiently a CO laser medium. In preliminary experiments, this pumping technique has produced a 34-W cw laser emitting over a band of vibration-rotation transitions from 4.9 to 5.7 μ from a 5-cm active transverse optical cavity.
Photocapacitance studies of deep-double-electron-trap oxygen in gallium phosphide
Authors: Kukimoto H. , Henry C.H. , Miller G.L.
Published: January 2004

Transitions of the deep O donor in a GaP p-n junction are studied by photocapacitance. It is found that the O donor may deeply trap either one or two electrons. The four optical absorption cross sections are measured for the two states, and from this information the O concentration profile is determined. The concentration ranges from (4 ± 1) × 1014 cm−3 on the n side to (1.5 ± 0.2) × 1016 cm−3 on the p side of the junction depletion layer. It is believed that these measurements represent the first direct determination of the concentration of O donors in GaP.
Platinum silicide-aluminum Schottky diode characteristics
Authors: Hosack H.H.
Published: January 2004

The effects of heat treatment on platinum silicide Schottky diodes with aluminum metal contacts have been investigated. It has been found that the aluminum reacts with the silicide causing a change in the effective metal-semiconductor barrier height over a range of approximately 0.25 eV. Schottky diodes with initial platinum silicide characteristics convert to devices with barrier heights characteristic of aluminum after extended heat treatments.
Relative importance of electrostriction and the Kerr effect to self-focusing in optical glasses
Authors: Feldman Albert , Horowitz Deane , Waxler Roy M.
Published: January 2004

The damage threshold for three optical glasses was found to be higher for circularly polarized radiation than for linear polarization, using 26-nsec pulses from a Nd:glass laser. The damage was assumed to result from self-focusing. The fractional contribution of electrostriction to the total nonlinear index n2 is estimated to be 0.8 ± 0.2 for borosilicate crown glass, 1.15 ± 0.35 for fused silica, and 0.4 ± 0.1 for dense flint glass, assuming the Kerr effect to be the only other self-focusing mechanism. The data are consistent with present concepts of glass structure. The high damage threshold in fused silica is attributed to its relatively small Kerr effect.
Intense-electron-beam excitation of the 3371-Å N2 laser system
Authors: Patterson E.L. , Gerardo J.B. , Johnson A. Wayne
Published: January 2004

The results of a parametric study of superradiant laser action at 3371 Å in the second positive band system of molecular nitrogen with excitation by a high-energy electron beam are reported. Efficiency up to 0.15% was observed for conversion of electron-beam power to laser power at 3371 Å. Laser output power up to 24 MW in a 6-nsec pulse was observed.