bluuebunny/crossref_metadata_2025 huggingface dataset:
Convolution and correlation by nonlinear interaction in a diode-coupled tapped delay line
Authors: Reeder T.M. , Gilden M.
Published: January 2004

A new type of nonlinear delay-line correlator is described which makes use of a tapped piezoelectric surface-acoustic-wave delay line and a series chain of forward-biased semiconductor diodes. Nonlinear signal mixing in the diode chain is utilized to perform serial product convolution or correlation of arbitrary signal modulation applied at two input ports. Because of the large nonlinearity available with semiconductor diodes, insertion loss for the new correlator is relatively low, approximately 25 dB for the initial experiments reported here. Convolution and correlation experiments are described for an eight-tap correlator operating with input and mixing frequencies in the 30- to 60-MHz range.
Acoustoelectric energy conversion in n-InSb
Authors: Aoki T. , Ogawa F. , Naito I. , Arizumi T.
Published: January 2004

Acoustoelectric energy conversion in n-type InSb has been investigated. Electromagnetic radiation is observed at 77°K when the externally injected acoustic wave arrives at the end of a sample. The frequency of the radiation is the same as that of the acoustic wave. Application of an electric field enhances its intensity, and a transverse magnetic field also affects it. Dependence of the conversion efficiency on the external field is shown.
Surface acoustic wave velocities on Gd2 (MoO4)3
Authors: Toda M. , Tosima S. , Shima E. , Iwasa T.
Published: January 2004

The propagation velocity of a surface acoustic wave on Z-cut Gd2(MoO4)3 has been measured. It has been found that the surface wave velocity is (2.086±0.003)×105 cm/sec in the X-axis (a-axis) direction and (2.149±0.003)×105 cm/sec in the Y-axis (b-axis) direction. The X and Y crystal axes have been interchanged by the dc voltage applied to the electrode on the surface, and thus the surface wave velocities were controlled electrically. The coupling constants k2 calculated from the radiation resistance are 7.2×10−4 for propagation in the X-axis direction and 4.0×10−4 in the Y-axis direction.
Pressure dependence of sound velocity in [001] plane of copper
Authors: Chung David Y. , Ljamov V.E.
Published: January 2004

The velocity surface of sound waves as a function of uniaxial pressure has been calculated by the use of the nonlinear acoustic theory of Ljamov et al. The result for the [001] plane of copper will be presented. Consistent results have been obtained when compared with the experimental measurements of Hiki and Granato in the pressure range below 1 kbar.
Optical probing of surface acoustic wave generation under interdigital transducers
Authors: Vella P.J. , Stegeman G.I.A.
Published: January 2004

High-resolution optical spectroscopy was used to study the growth of continuously excited surface acoustic waves under 15- and 25-finger-pair aluminum interdigital transducers on y-cut z-propagating lithium niobate. The observed exponential growth of the surface wave with distance is in agreement with simple coupled-mode theory. The coupling parameter leads to a direct evaluation of the effective electromechanical coupling constant K. For yz LiNbO3 a value of K2=0.030±0.003 was found.
Surface acoustic wave losses of thin-film gratings
Authors: Szabo Thomas L.
Published: January 2004

Measurements of surface acoustic wave losses of thin-film gratings on piezoelectric substrates have been made by a real-time laser probe technique. For a 130-line chrome-aluminum shorted grating on Y-cut Z-propagating LiNbO3, 70% of the power incident on the grating was reflected, 4% was transmitted, and 26% was lost at the resonant grating frequency of 308.5 MHz. A transmission-line model applied to the measurements indicates an impedance discontinuity ratio between the film and substrate of Z = 1.018.
Superresolution in optical data storage
Authors: Wieder Harold
Published: January 2004

By exploiting the threshold nature of the temperature of amorphization in a crystalline film of TeGeAs, digital information was recorded at a density higher than that obtainable with a linear storage medium. This information was read out optically with a scanning GaAs laser by choosing such an operating level for the laser that optical feedback from the crystalline state raised the laser above threshold, while feedback from the amorphous state did not. The use of these nonlinear techniques increases the recording and readout information density of an optical store beyond the limit imposed by optical diffraction.
Propagation of acoustic surface waves in multilayers: A matrix description
Authors: Fahmy A.H. , Adler E. L.
Published: January 2004

A matrix formalism is outlined for studying surface wave propagation in layered structures utilizing materials of arbitrary anisotropy, piezoelectricity, and conductivity. The analytical formulation reduces the equations describing the system to a first-order matrix differential equation which is readily solved. The conceptual advantages and reduction of programming effort and computing time resulting from this approach are illustrated using as examples an infinite plate, a multilayer plate, a layered half-space, and a free half-space.
Ignition and maintenance of a cw plasma in atmospheric-pressure air with CO2 laser radiation
Authors: Smith David C. , Fowler Michael C.
Published: January 2004

The focused output from a high-power cw CO2 laser is used to study the maintenance of a plasma in atmospheric-pressure air. The plasma is initiated externally by an electric spark and maintained by the absorbed laser beam energy. Ignition has also been observed when the laser was focused on a solid target. The maintenance threshold is examined as a function of beam diameter; for beams smaller than 1 mm the threshold power is ∼2 kW. When focused with lenses of 14-cm focal length and shorter, the plasma ball is stationary, situated slightly ahead of the focal point. For this focusing system, the transmission through the plasma was a function of incident power and increased with decreasing laser power. The value of the measured plasma absorption coefficient corresponds to an electron temperature of 14 000°K. When the laser beam was focused with 25-cm—focal-length mirrors or larger, the plasma was not stationary but propagated up the beam at a velocity of ∼10 m/sec toward the laser before extinguishing. The maintenance threshold of the plasma is discussed in terms of the loss channels from the plasma.
Characteristics of a cold cathode plasma electron gun
Authors: O'Brien B.B.
Published: January 2004

A plasma discharge is described which can produce a large-area electron beam with energies up to 150 kV and current densities in excess of 1 A/cm2 for durations of the order of 20 μs. For voltages up to ∼120 kV, durations of 100 μs or longer are attainable without arcing in the discharge. The discharge has a smooth cathode and will operate with various fill gases at pressures of about 10 μ. The device is being developed as an electron gun for high-pressure laser discharge stabilization.
Anomalously large thermoelectric cooling figure of merit in the Kondo systems CePd3 and Celn3
Authors: Gambino R.J. , Grobman W.D. , Toxen A.M.
Published: January 2004

Measurements of thermopower, resistivity, and thermal conductivity for the rare-earth intermetallic compounds CePd3 and CeIn3 indicate an anomalously large Peltier effect cooling figure of merit at low temperatures associated with a large thermopower. Resistivity and susceptibility measurements indicate that these compounds possess localized Ce 4f electrons which give rise to the Kondo effect and thermopower enhancement. These results suggest that a survey of Ce intermetallic compounds could lead to new materials for low-temperature thermoelectric cooling applications.
An efficient plasma surface-wave coupler
Authors: Sorensen T.P. , Ristic V.M.
Published: January 2004

A plasma surface-wave coupler consisting of interdigital metallic rings is described and the comparison between the theoretical and experimental results is presented. The coupling loss per coupler is 4 dB at the frequency of 52 MHz measured on an experimental setup consisting of a plasma tube and two couplers spaced 25 cm apart. The coupler is insensitive to slow-temporal and slow-spatial variations of the plasma frequency. The coupler can be used in plasma laser and plasma torch applications.
Three-dimensional light guides in single-crystal GaAs–Alx Ga1 − xAs
Authors: Tracy J.C. , Wiegman W. , Logan R.A. , Reinhart F.K.
Published: January 2004

A technique is described for fabricating miniature dielectric waveguides of GaAs embedded in a matrix of AlxGa1−xAs. The method appears to have general applicability for generating complex integrated optical circuits using the AlxGa1−xAs system. The film growth employs molecular beam epitaxy (MBE), while the pattern generation is based on photolithography combined with a recently developed anodization technique.
New chemically pumped CO2 and N2O lasers
Authors: Searles S.K. , Airey J.R.
Published: January 2004

Laser oscillation, based on the transfer of vibrational energy from OD(OH) to CO2 and from OD to N2O, was observed during the flash photolysis of mixtures containing ozone.
Extension of microwave spectroscopy techniques to the infrared region
Authors: Corcoran V.J. , Martin J.M. , Smith W.T.
Published: January 2004

High-resolution frequency-measuring spectroscopy techniques have been extended to the infrared region for the first time. The initial data obtained from this spectrometer are gain versus frequency for CO2 transitions. The gain line profile of the P(18) line of the 00°1 → 10°0 vibrational band of CO2 is reported between 1 and 12 Torr. The slope of the collison contribution to the linewidth is determined to be 4.46 MHz/Torr at 296°K in a mixture of 14% CO2, 17% N2, and 69% He.
Interrelationship between the saturated drift velocity and impact ionization of electrons in silicon
Authors: Lanyon H.P.D.
Published: January 2004

The saturated drift velocity of electrons in silicon is explained in terms of a tight coupling between electrons and optical phonons with an energy of 46.8 meV. In the saturated regime the scattering time is inversely proportional to the electric field, which results in a spread of carrier energies increasing with the electric field. The field dependence of the ionization coefficient may be explained if a drifted Maxwellian distribution is assumed. In this field range the electron temperature T* is due to randomized motion in the plane perpendicular to the electric field direction and is related to the scattering time τ through the relationship kT*=h/τ, where h is Planck's constant. Excellent numerical agreement is found between the theoretical predictions and all experimentally observable quantities.
Fundamental optical attenuation limits in the liquid and glassy state with application to fiber optical waveguide materials
Authors: Pinnow D.A. , Rich T.C. , Ostermayer F.W. , DiDomenico M.
Published: January 2004

Fundamental optical scattering and absorption mechanisms have been identified which limit light transmission in fiber optical waveguide materials. These mechanisms, which are intimately associated with the random structure in the liquid and glassy state, are described and then used as a basis for comparing fiber optical waveguide materials. It is concluded that pure fused silica is a preferred waveguide material, having ultimate total losses of 1.2 dB/km at the Nd : YAG laser wavelength of 1.06 μ, 3.0 dB/km at the GaxAl1−xAs emission wavelength of approximately 0.8 μ, and 4.8 dB/km at the GaP : Zn, O emission wavelength centered at 0.7 μ.
Theoretical origins of Nss peaks observed in Gray-Brown MOS studies
Authors: Boudry M.R.
Published: January 2004

A MOS device has been modelled on a computer by using interface state parameters previously measured by a parallel conductance technique. A Gray-Brown measurement was simulated, and the resulting apparent interface state distribution was found to show a large peak near the band edge, although the known distribution was in fact monotonic. This spurious peak is associated with a rapid decrease in interface state capture cross section as the band edge is approached, and is seen when the measurement frequency is insufficiently high.
Green light emission from Zn-doped AlxGa1−xP alloys
Authors: Sonomura H. , Nanmori T. , Miyauchi T.
Published: January 2004

AlxGa1−xP alloys with an x=0.74 composition are prepared by solution growth method. The composition is determined from the density measured by using a heavy solution. The energy gap of the alloys shifts to a higher energy side than that of GaP by approximately 0.15 eV. Alloys doped with Zn emit green light of 535-nm wavelength at room temperature.
Nd-ultraphosphate laser
Authors: Weber H.P. , Damen T.C. , Danielmeyer H.G. , Tofield B.C.
Published: January 2004

Laser action at λ=1.051 μm with a bandwidth of 1.4 nm is reported in a 35-μm-thick platelet of a neodymium-ultraphosphate crystal (NdUP) placed within an optical resonator. Longitudinally pumped with a pulsed rhodamine 6G laser (λ=0.58 μm) the room-temperature threshold was 40 μJ and the quantum efficiency slope was ∼18%. Also in glass of the same chemical composition laser action was observed.
Pulsed holographic interferometry at 10.6 μm
Authors: Forman P. R. , Humphries Stanley , Peterson R. W.
Published: January 2004

Double-exposure holographic interferograms using a 10.6-μm pulsed CO2 laser as the radiation source are shown. Results using two recording media, thin bismuth films, and cuprous mercuric iodide are reported.
Thin-film LiNbO3 electro-optic light modulator
Authors: Kaminow I.P. , Carruthers J.R. , Turner E.H. , Stulz L.W.
Published: January 2004

An out-diffused planar optical waveguide in LiNbO3 has been used to produce an efficient broad-band electro-optic phase modulator. The ratio of modulation index η and voltage is 0.13 V−1, the maximum base bandwidth with 50-Ω load is 3.2 GHz, and the modulating power per unit bandwidth for η=1 rad is 0.2 mW/MHz.
Characteristics of a low-field spin-flip Raman laser: Measurement of Raman gain
Authors: DeSilets C.S. , Patel C.K.N.
Published: January 2004

The operation of a low-field spin-flip Raman (SFR) laser utilizing a closed-cycle refrigerator is reported. SFR laser conversion efficiencies as high as 80% have been observed enabling us to observe the operation of a IV Stokes SFR laser for the first time. SFR gain in InSb is measured that gives a spontaneous SFR linewidth as narrow as ∼ 400 MHz.
Comparison between the constant-potential steps of two point-contact Josephson junctions
Authors: Macfarlane J.C.
Published: January 2004

Microwave-induced steps in the current-potential characteristics of two niobium point-contact junctions have been compared using a SQUID voltmeter with a resolution of less than 10−12 V. It has been established that the uncertainty in step potential at the 1-mV level is less than 2 in 109.
Recoil fraction technique for measuring nuclear and electronic stopping powers
Authors: Shnidman R. , Tapphorn R. M. , Geller Kenneth N.
Published: January 2004

A new technique for measuring nuclear and electronic stopping powers of heavy ions in solids is described. The method does not require direct acceleration of the heavy ions nor does it require ultrathin uniform film targets. The method should be useful from the MeV region down to tens of keV. Results for carbon ions in carbon from 0.5 to 1.4 MeV are presented.
Bragg diffraction of light by two orthogonal ultrasonic waves in water
Authors: Chu W.P. , Mauldin L.E.
Published: January 2004

The diffraction of a light beam by two orthogonal traveling ultrasonic waves in water under Bragg angle incidence is described. It is shown that under low index modulation, only the zero order (0, 0), the two minus one orders (−1, 0 and 0, −1), and the cross minus one order (−1, −1) predominate in the diffraction process. Equalization of the four beam intensities, which is required in a two-component cross-beam laser Doppler velocimeter system, can be achieved with the transducers being driven at low power levels.
Electro-optic switching in low-loss liquid-crystal waveguides
Authors: Sheridan J.P. , Schnur J.M. , Giallorenzi T.G.
Published: January 2004

Observation of low-loss optical guidance in thin films of a number of well-aligned nematic liquid crystals is reported for the first time. Evaluation of waveguiding properties of the oriented films and polarized microscopic techniques indicates a high degree of alignment can be attained and, indeed, is essential for good waveguiding. Propagation losses in the best samples are measured to be less than 1 dB/cm. Amplitude modulation and switching in these waveguides have also been achieved using the unique electro-optic properties of nematic materials. The response times for these phenomena are on the order of a few milliseconds.
Tunneling in a finite superlattice
Authors: Tsu R. , Esaki L.
Published: January 2004

We have computed the transport properties of a finite superlattice from the tunneling point of view. The computed I-V characteristic describes the experimental cases of a limited number of spatial periods or a relatively short electron mean free path.
Estimation of impurity profiles in ion-implanted amorphous targets using joined half-Gaussian distributions
Authors: Gibbons J.F. , Mylroie S.
Published: January 2004

A probability distribution function appropriate for nonsymmetrical impurity distributions in ion-implanted targets is defined to consist of two half-Gaussian distributions that join at a modal projected range RM. For projected distances XpRm the distribution has standard deviation σ2. For appropriate choices of RM, σ1, and σ2, the proposed distribution is found to provide an extremely good fit for experimental impurity profiles.
Enhanced diffusion during the implantation of arsenic in silicon
Authors: Schwettmann F.N.
Published: January 2004

The ``tail'' that is observed on the arsenic carrier profile formed by the implantation of arsenic in silicon is shown to be due to enhanced diffusion during implantation. The position of the tail is unaffected by postimplant annealing at temperatures up to 1000 °C. The arsenic ions comprising the tail are electrically inactive after implantation, and temperatures in excess of 700 °C are required to achieve complete activation. While the nature of the migrating species is unclear at this time, the results are consistent with an interstitial mechanism.
Frequency stabilization of a cw dye laser
Authors: Barger R. L. , Sorem M.S. , Hall J.L.
Published: January 2004

A cw dye laser system frequency stabilized to a high-finesse optical reference cavity is described. Laser frequency is servo controlled to the cavity resonance with residual fluctuations less than 50 kHz for short times (20 μsec) and 100 Hz for long times (10 sec). Drift in absolute laser frequency of about 1.5 MHz/min is observed due to drift of the unstabilized reference cavity. A saturated absorption spectrum of I2 obtained with this system is shown.
Vibrational excitation and relaxation of the CO(v=1) and CO(v=2) states
Authors: Stephenson John C.
Published: January 2004

Pulses from a CO2 laser have been frequency doubled in a tellurium crystal and used to optically pump the first vibrational level in room-temperature CO. By monitoring infrared fluorescence from the v=1 and v=2 states, the rate constant for the process CO(v=1) + CO(v=1) → CO(v=0) + CO(v=2) has been determined. Other rate constants involving the CO(v=1) level are also reported.
Ionization instability in CO2 laser discharges
Authors: Nighan William L. , Wiegand W.J. , Haas Roger A.
Published: January 2004

Criteria are established for calculation of plasma conditions leading to ionization instability in plasmas generally employed in high-power molecular laser applications. Negative ion formation is found to play an important role in causing this instability. For conditions typical of electrically excited CO2 laser mixtures, appearance of an ionization instability requires a negative ion concentration greater than one-tenth that of the electrons, combined with an electron temperature value below approximately 1.5 eV. Satisfactory agreement between theoretically determined stability boundaries and data obtained experimentally confirms the significance of fundamental collisional processes as regards ionization instability in CO2 laser discharges.
cw CO chemical laser directly fueled by carbon monosulfide
Authors: Jeffers W.Q. , Wiswall C.E. , Kelley J. Daniel , Richardson R.J.
Published: January 2004

A cw CO chemical laser has been operated with CS produced externally by a microwave discharge. Use of CS as a laser fuel produces large increases in output power, as compared with CS2, by a factor of 5.6 or more. The reasons for this power enhancement and the details of the experiment are discussed in this letter.
Reduction of threshold current density in GaAs–Alx Ga1−x As heterostructure lasers by separate optical and carrier confinement
Authors: Panish M.B. , Casey H.C. , Sumski S. , Foy P.W.
Published: January 2004

Heterostructure lasers in which the GaAs active layer is bounded on each side by successive layers of AlxGa1−xAs to confine the carriers and AlyGa1−yAs (y>x) to confine the light have been fabricated and studied. Room-temperature threshold current densities as low as 690 ± 40 A/cm2 with differential quantum efficiencies of 32% have been obtained for 1-mm cavity lengths.
Remote detection of SO2 and CO2 with a heterodyne radiometer
Authors: Menzies Robert T.
Published: January 2004

A heterodyne radiometer, operating in the 9- to 11-μm wavelength region, has been used to detect SO2 and CO2 in the laboratory with sensitivity adequate for remote stack monitoring and other sensing applications. CO2 lasers were used as local oscillators. The mixer was copper-doped germanium, compensated with antimony donors, and the i.f. bandwidth was 500 MHz. Wavelengths of operation were chosen to minimize interference from water vapor.
Magnetic anisotropy of Eu0.65Y2.35Fe3.8Ga1.2O12 films grown on garnet substrates with different lattice parameters
Authors: Giess E.A. , Cronemeyer D.C.
Published: January 2004

The effect of lattice mismatch (stress) on magnetic anisotropy is studied in epitaxial films of a Eu0.65Y2.35Fe3.8Ga1.2O12 garnet grown on a series of garnet substrates with different lattice parameters. These garnet films have a negative magnetostrictive coefficient (λ ≃ 0.5 × 10−6) as predicted by simple magnetic dilution theory. A ``growth''-induced magnetic anisotropy (Ku ≃ 8300 erg/cm3) will exist for all of these films even when they are grown on a substrate with a perfect lattice match. Anisotropy can be increased by using an increased substrate rotation rate during film deposition.
Suppression of hard bubbles by a thin Permalloy layer
Authors: Lin Y.S. , Keefe G.E.
Published: January 2004

We show experimentally that, by placing a thin Permalloy layer in intimate contact with a garnet film, hard bubbles can be suppressed. The suppression is due to exchange coupling between the Permalloy layer and the bubble walls. When the Permalloy layer is separated from the garnet film by a thin insulation layer, intermediate bubbles are observed.
Elasticity effect in rotational decay experiments
Authors: Comsa George , Fremerey J.K.
Published: January 2004

A general first-order approximation correction is presented which has to be applied to the theoretical frequency decay ratio -ω̇/ω of a rigid rotor in order to find the corresponding ratio for a real elastic rotor. The procedure is exemplified for the particular drags associated with gas friction and with the Coriolis effect acting on steel spheres. In these cases the decay ratio is at most about 1% smaller than that of the corresponding rigid sphere.
High-resolution thermionic cathode scanning transmission electron microscope
Authors: Broers A.N.
Published: January 2004

A new scanning transmission electron microscope has been built which uses a lanthanum hexaboride thermal cathode electron gun. Initial results indicate a beam diameter of 5 Å and point-to-point resolution of 7 Å. The vacuum level in the instrument is similar to that of standard commercially available electron microscopes. A comparison of the performance of tungsten hairpin, lanthanum hexaboride, and field emission cathodes for scanning transmission electron microscopy is given.
Effect of 80-keV Ne+ ion implantation on acoustic surface wave attenuation in LiNbO3
Authors: Larson T.R. , Weisenberger W.H. , Lucke W.H.
Published: January 2004

Acoustic surface wave attenuation in LiNbO3 caused by ion implantation was studied as a function of fluence and surface wave frequency. 80-keV Ne+ ions were implanted at five fluences covering the range 1014–1016 ions/cm2. The yz Rayleigh surface waves were generated spanning the interval 100–1000 MHz by interdigital transducers operating at odd harmonics. Attenuation was measured directly by a standard laser probe using reflected light. At low acoustic power densities, the data can be fit by P(z)/P0=10−Af2z, where P is acoustic power, f is the surface wave frequency, and A is a constant for each fluence used. The values of A show a definite peak with fluence at around 1015 ions/cm2, where A=9 × 10−5 dB cm−1 MHz−2±10%. This is about twenty times the value of A for an unimplanted surface.
Scattering of sound by sound in solids
Authors: Rouvaen J.M. , Bridoux E. , Torguet R.
Published: January 2004

We show in this letter that nonlinear interactions between noncollinear elastic waves can be analyzed by using the well-known mathematical formalism of wave propagation in periodic media, which leads to a set of coupled amplitude equations much like those found in the optoacoustic interaction case. The behavior predicted from these equations for isotropic media is well consistent with results known for Bragg diffraction in anisotropic media. The conditions for an experiment using a lead molybdate crystal are derived. By using the optoacoustic analogy, some device applications may be thought of and the scope of the present work may be extended to cover interactions involving elastic surface waves.
Direct observation of Dauphiné twins in quartz with second-harmonic light
Authors: Dolino G. , Bachheimer J.P. , Vallade M.
Published: January 2004

Dauphiné twins in quartz have been directly observed and photographed by using second-harmonic light. A theoretical analysis shows that a plane twin boundary in a plane parallel slab of quartz produces a system of interference fringes at the crystal output surface, corresponding to the existence of two second-harmonic beams with different directions. This was experimentally verified, and thus a topography of the twins has been obtained. Furthermore, the orientation of the twins relative to a twinless quartz crystal has been determined.
Study of the wavelength dependence of optically induced birefringence change in undoped LiNbO3
Authors: Serreze H.B. , Goldner R. B.
Published: January 2004

Optically induced birefringence change (``optical damage'') has been studied in undoped LiNbO3 from 400 to 800 nm by using an incoherent light source. Optical damage was observed over the entire wavelength range, with damage peaking near 415 nm. Structure, which could not be observed by normal optical absorption measurements, was seen in at least three regions of the damage-wavelength curve.
Photovoltaic effect in amorphous-silicon-electrolyte interface
Authors: Chan Y.K. , Jayadevaiah T.S.
Published: January 2004

By studying the photovoltage developed across the amorphous silicon-electrolyte interface on illumination with monochromatic light, the mobility gap in amorphous silicon is found to be about 1.7 eV. The effect of preparation conditions is very significant, with unannealed films deposited by electron beam evaporation showing considerable structure in the spectral response. After low-temperature annealing, typically at 120°C for 20 h, the spectral response shows a sharp edge and is similar to that of single-crystal silicon but is displaced to higher energies by about 0.6 eV. Sputtered films, even when unannealed, show almost identical spectral response as fully annealed films, which is attributed to the process of film growth in the sputtering process.
Lowering of breakdown voltage of semiconductor silicon due to the precipitation of impurity carbon
Authors: Akiyama N. , Yatsurugi Y. , Endo Y. , Imayoshi Z. , Nozaki T.
Published: January 2004

The lowering of breakdown voltage and the softening of V-I curves of silicon diodes, caused by the precipitation of impurity carbon, have been observed.
Formation mechanisms in an excited-state-reaction dye laser
Authors: Dienes A. , Jain R.K. , Lin C.
Published: January 2004

The formation mechanisms in an excited-state-reaction coumarin laser dye are investigated by measurements of the saturation characteristics of the laser. By recording the influence of intense cavity oscillation on the single- and double-pass amplified spontaneous emissions of the two different ``exciplex'' species, it is found that a ``serial'' model applies, the green-emitting species being formed from the blue-emitting one.
High peak power from (GaAl)As–GaAs double-heterostructure injection lasers
Authors: Kirkby P.A. , Thompson G.H.B.
Published: January 2004

Double-heterostructure (GaAl)As–GaAs injection lasers have been made with very narrow active regions in the range 0.11–0.14 μm. In addition to giving narrow angular beam widths down to 16°, they show high peak power handling capacity up to 40-W/mm junction width at threshold current densities of less than 1500 A/cm2. The results are consistent with the relatively wide near-field distribution perpendicular to the junction plane, which is deduced from the properties of the heterostructure optical waveguide.
Dielectric thin-film optical branching waveguide
Authors: Yajima Hiroyoshi
Published: January 2004

Glass thin-film optical branching waveguides have been fabricated by sputtering. It is found that the dielectric branch has functions of mode filtering and mode conversion. The concept of dielectric branch offers many possibilities to integrated optical circuitry.
Charge-coupled memory device
Authors: Chan Y.T. , French B.T. , Gudmundsen R.A.
Published: January 2004

Charge-coupled devices with silicon-nitride-silicon-oxide composite gate dielectric layers have been shown to exhibit electrically alterable static memory. The storage of charge und under a specific gate by combined charge transfer and tunneling into memory states and the detection of its presence at a later time have been demonstrated.
Gain and energy measurements on an HF/DF electrically pulsed chemical laser
Authors: Jones C.R.
Published: January 2004

The peak small-signal gain and output energy of an electrically initiated chemical laser are measured for both HF and DF operation. For identical conditions of electrical discharge and gas mixture [SF6–H2(D2)–He], the DF laser small-signal gain coefficient is about a factor of 2 below that for HF, while in the oscillator configuration the output energies for the two cases are equal. The gain threshold is determined for parasitic oscillations, which can be avoided only under medium conditions corresponding to relatively low output energy. The maximum parasitic-free energy with DF is about ten times that with HF.
Generation of intense infrared radiation from an electron beam propagating through a rippled magnetic field
Authors: Friedman M. , Herndon M.
Published: January 2004

Electromagnetic radiation in the far-infrared region of the spectrum was produced by the interaction between a relativistic electron beam and a spatially modulated magnetic field. Power of the order of megawatts was observed at wavelengths greater than about 50 μ. The radiation does not originate from a simple synchrotron mechanism, and one has to invoke other processes.
Inadvertent deep centers in n-type GaP from Schottky barrier photocapacitance
Authors: Hamilton B. , Smith B.L.
Published: January 2004

Deep levels arising from inadvertent defect centers have been studied in both liquid-encapsulated-Czochralski (LEC) and liquid-phase-epitaxial (LPE) n-type GaP by using Schottky barrier photocapacitance. In LEC material the total concentration of deep levels in the upper half of the band gap is determined to be about 5×1016 cm−3; in LPE material, about 5×1014 cm−3. In the lower half of the band gap, optical emission of majority carriers and thermal emission of minority carriers are observed from two distinct levels at 0.4 and 0.1 eV above the valence band edge. These levels are found to have similar concentrations of about 1×1016 cm−3 in both LPE and LEC material.
Tunable cw Pb0.98 Cd0.02S diode lasers emitting at 3.5 μm: Applications to ultrahigh-resolution spectroscopy
Authors: Nill K.W. , Strauss A.J. , Blum F.A.
Published: January 2004

Continuously tunable cw diode lasers that produce narrow-line (1- to 10-MHz linewidth) radiation in the 3.5-μm region have been fabricated from Pb0.98Cd0.02S. Lasers operating at 10–20 K produced more than 1 mW of cw power distributed among several modes which could be tuned continuously > 1 cm−1 by adjusting the laser current. A spectral range of 30 cm−1 could be covered over the full operating range. Ultrahigh-resolution (10−5 cm−1) spectra of H2CO have been obtained to demonstrate the potential application of these lasers to the identification of organic molecules by spectroscopy of their C–H stretch absorption bands.
Measurement of the spectrum of a helical TEA CO2 laser
Authors: Stiehl W.A. , Hoff P.W.
Published: January 2004

Measurements of the chirp of individual TEA CO2 laser pulses are reported. Rates of chirping during the peak and the tail are attributed to two different mechanisms. Spectrum analyzer results corroborate the time-resolved measurements.
Magnetic domains of a sintered SmCo5 magnet
Authors: Goto Kimiyoshi , Sakurai Tomoaki , Yazaki Takashi
Published: January 2004

Magnetic domains of a press-sintered SmCo5 magnet with a high intrinsic coercivity (IHc = 12 700 Oe) and energy product [(BH)max = 18.0 MGOe] were observed in the demagnetized state by the powder pattern technique. The domains on the surfaces parallel and perpendicular to the alignment direction and at grain boundaries are shown in detail. The domain structures observed are of the same type as those for thick crystals with high uniaxial anisotropy, such as MnBi and BaFe12O19.
Observation of laser oscillation in a 1-atm CO2–N2–He laser pumped by an electrically heated plasma generated via photoionization
Authors: Levine J.S. , Javan A.
Published: January 2004

The photoionization of a large organic molecule, tri-n-propyl amine, mixed with a 1-atm CO2–N2–He gas is used to produce a high-electron-density uniform large-volume laser plasma. Photoionization by a two-photon two-step process is found to be the dominant mechanism when illumination is by a xenon flashlamp employing a quartz envelope. Electron density on the order of 1013/cm3 is obtained. The electrons are heated by an externally applied electric field less intense than that required to produce avalanche breakdown. Laser oscillation is observed on the P(20) line of the 10.6-μ CO2 band with a maximum output of 300 mJ obtained from a 0.02-liter active volume (corresponding to 15 J/liter). The energy output as a function of E/P is studied and found to peak at a value below breakdown.
Divacancylike optical absorption in Si0.5Ge0.5 alloy
Authors: Stein H.J.
Published: January 2004

The first absorption band for an irradiation-induced defect in SiGe alloys has been observed at 2.15-μm (90 K) in Si0.5Ge0.5 following neutron or proton bombardment. The 2.15-μm band is similar in width and thermal stability to the 1.7-μm divacancy band in Si, but the band position is closer to a 2.4-μm band tentatively ascribed to divacancies in Ge. A distinct divacancylike band in the bombarded SiGe suggests either some structural order in the alloy or structural selectivity in defect formation. Absence of characteristic Si or Ge bands implies that the alloy is free from any significant amount of Si or Ge aggregates.
Imaging of surfaces with the exoelectron microscope
Authors: Bräunlich P. , Rosenblum B. , Carrico J.P. , Himmel L. , Rol P.K.
Published: January 2004

A simple exoelectron emission microscope is described, first images obtained from BeOceramic are reported, and potential applications of the device in surface characterization of a wide variety of solids are discussed.
Aluminum fluoride exploding-wire laser
Authors: Rice Walter W. , Jensen Reed J.
Published: January 2004

Intense aluminum fluoride laser pulses in the spectral range 12.5–13.5 μ were observed when fine aluminum wires were exploded into fluorine gas. The laser oscillation occurred during the expansion phase of the wire explosion.
Fabrication and Jc(H,T) measurements on Nb3Al0.75Ge0.25 ribbon
Authors: Löhberg R. , Eagar T.W. , Puffer I.M. , Rose R.M.
Published: January 2004

Ribbons of composition Nb3Al0.75Ge0.25 have been fabricated by swaging, rolling, and heat treatment. Measurements of Jc in steady transverse magnetic fields up to 150 kOe at temperatures up to 16°K show values of the order of 104 A/cm2 at 13°K and 120 kOe, and 103 A/cm2 at 16°K and 95 kOe.
Gigawatt photochemical iodine laser
Authors: Hohla K. , Kompa K.L.
Published: January 2004

An oscillator-amplifier iodine laser system has been set up to demonstrate the feasibility of high-power operation of this laser. Pulse powers of 1.2 GW have been obtained with two amplifier stages. Technical details and relevant laser parameters are discussed.
Superfluorescence in N2 and H2 electron-beam-stabilized discharges
Authors: Nelson L.Y. , Mullaney G.J. , Byron S.R.
Published: January 2004

Previous N2 and H2 electronic transition lasers have been limited to short pulse durations (10−9–10−7 sec). Using an electron-beam-stabilized discharge in argon, nitrogen (or hydrogen), and hydrogen fluoride mixtures, we have observed repetitive superfluorescent pulses lasting 5–20 μsec. Optical-cavity measurements verify that optical gain is present throughout the pulse duration at wavelengths in the nitrogen first- and second-positive band systems and in a hydrogen near-infrared band system. It is believed that HF serves to maintain a population inversion for a longer period of time by providing preferential collisional deactivation of the lower laser levels.
Analysis of formation of hafnium silicide on silicon
Authors: Kircher C.J. , Mayer J.W. , Tu K.N. , Ziegler J.F.
Published: January 2004

Backscattering of He ions and Seemann-Bohlin x-ray diffraction techniques have been used to investigate the composition and growth kinetics of hafnium silicide formed from thin films of hafnium sputter deposited on silicon. The stable-phase HfSi was formed in the temperature region 550–750°C. Zirconium and argon impurities were present in the Hf films at the level of 2.5 at.%. During the formation of the HfSi phase, these impurities served as markers which were used to determine the diffusing species. We conclude that Si is the diffusing species.
Electron diffusion in CdTe
Authors: Quaranta A. Alberigi , Borsari V. , Jacoboni C. , Zanarini G.
Published: January 2004

Electron diffusion as a function of applied field has been studied for CdTe at 300°K with the Monte Carlo technique. The high energy separation between central and satellite valleys makes the limitations on the use of the macroscopic equation of diffusion particularly severe. At fields around the threshold value for negative differential mobility, polar optical scattering produces uneven initial spreading of a delta distribution of electrons. Furthermore, at fields around and above threshold the large spread of electron velocities causes an initial diffusion much greater than that predicted by the macroscopic equation. This latter effect may be very important in small devices as, in particular, in the dynamics of Gunn domains.
Trap structure of pyrolytic Al2O3 in MOS capacitors
Authors: Harari E. , Royce B.S.H.
Published: January 2004

The trap structure of the pyrolytic Al2O3 layer of MOS capacitors was investigated by a technique in which the capacitor was used as an integral detector of the charge trapped in the oxide. In all the samples studied, five trap levels were found to exist extending from 2.2 to 4.5 eV below the oxide conduction band. The spatial distribution of these traps was inferred from complementary photoconductivity measurements. This method is applicable to the study of the effects of radiation damage and ion implantation on the trap structure of this and other thin film insulators.
Effect of ionizing radiations on metal-polymer-silicon structures
Authors: Ai Bui , Carchano H. , Sanchez D.
Published: January 2004

The effect of electronic bombardment on metal-polymer-silicon structures is considered. The polymer film was obtained by polymerization of monomer vapor (styrene) in an ac glow discharge. The relative dielectric constant of the films is 3 and the dissipation factor is 0.01. Under 25-keV electronic bombardment at various flux levels and with different polarizing voltages applied, the shifts of the C(V) curve are always in the opposite direction to that induced by the polarizing voltage. The displacement under irradiation is lower than observed with the metal-silicon dioxide-silicon structure. It is remarkable that the radiation effects are not permanent. The structures do not have any memory of irradiation constraints.
Microwave power absorption by a plasma outside the electron cyclotron resonance region
Authors: Bernabei S. , De Dionigi R. , Fontanesi M.
Published: January 2004

Microwave power absorption has been studied in the production of a plasma using interdigital and helical coils in conditions different from electron cyclotron resonance. It is observed that the plasma can be maintained only when resonances of the hybrid type exist in the plasma column.
ac liquid-crystal light valve
Authors: Beard T.D. , Bleha W.P. , Wong S.-Y
Published: January 2004

An ac-operated liquid-crystal light valve has been constructed and operated. The multilayer structure, consisting of a photoconductor, light-absorbing layer, dielectric mirror, and liquid crystal, is capable of efficiently modulating a high-intensity light beam with a comparatively weak light source. The dielectric mirror and absorbing layer provide high reflectance and optical isolation without the use of a metal mosaic reflector. The use of ac and insulated electrodes promises long lifetime. The light valve is applicable to television projection display and optical data processing.
Backscattering study on lateral spread of implanted ions
Authors: Furukawa Seijiro , Matsumura Hideki
Published: January 2004

Without ambiguities due to the cutting angle of a mask edge and the annealing process, the lateral spread of implanted Kr ions into Si substrates has been directly measured by the He+ backscattering technique. The experimental results show good agreement with theoretical predictions.
Response of edge- and face-electroded pyroelectric detectors to infrared laser signals
Authors: Simhony M. , Shaulov A. , Lavi S.
Published: January 2004

Expressions are given for the peak voltage responses to infrared laser signals in pyroelectric detectors with edge electrodes (EE) and face electrodes (FE). When the response is independent of the capacitance Cs of the samples, the FE detector has a much higher responsivity. When the response depends on Cs and the capacitance Ci of the preamplifier input is negligible for both samples, the EE design can give only a slightly higher response (the high gain expected in the literature comes from considering the EE sample as a parallel-plate condenser). However, when CsEE << Ci << CsFE, the EE detector response is higher by a factor of εl/Ci, where ε is the permittivity and l is the length of the edge electrodes.
Superlinear dependence of photon drag voltage on incident power density
Authors: Kamibayashi Teruho , Yonemochi Sigenobu , Miyakawa Toru
Published: January 2004

The photon drag effect in semiconductors has been studied over a wide range of light intensities. The experiment was carried out on p-type germanium samples by means of a TEA CO2 laser at 10.6 μm with a peak power of 1.2 MW. The superlinear dependence of photon drag voltage on incident power density was observed at room temperature for a sample of 2.6-Ω cm resistivity.
Focusing of EM waves in plasmas by inhomogeneous magnetic fields
Authors: Sodha M.S. , Chakravarti A.K. , Phadke U.P. , Gautama G.D. , Rattan I.
Published: January 2004

A new method of focusing electromagnetic (EM) waves in a plasma by means of a radially inhomogeneous magnetic field arrangement has been proposed. It is seen that the beam gets periodically focused in the plasma; for typical parameters, a focusing length of ∼ 1.05 cm has been predicted.
Direct observation of ferroelectric domains in TGS with second-harmonic light
Authors: Dolino G.
Published: January 2004

Ferroelectric domains in a triglycine sulfate crystal have been directly observed and photographed using second-harmonic light produced by a 1.06-μ laser beam in a phase-matching direction. A contrast inversion is observed when the crystal is slightly misaligned. Movements of domains during polarization switching under application of a dc electric field have been followed.
Laser oscillation in leaky corrugated optical waveguides
Authors: Zory Peter
Published: January 2004

The characteristics of laser action in leaky corrugated optical waveguides have been investigated using a spectroscopy technique which enables one to determine the guide index and vacuum wavelength differences of the oscillating modes. It is shown that an anomalous spatial beating phenomenon observed in the leaky waves coupled out through the side of the waveguide is due to laser oscillation on a hybrid guided mode where the feedback is provided by backward intermode diffraction. Also discussed are phenomena which can be utilized in multimode devices of this type to restrict the distributed-feedback laser oscillation to narrow-band polarized operation on the lowest-order waveguide mode.
Photoinitiated transversely sustained CO2 laser
Authors: Cohn D.B. , Ault E.R.
Published: January 2004

A uniform self-sustaining discharge is initiated in a high-pressure CO2 : N2 : He mixture by photons from a series of intense arcs, and subsequently sustained for times on the order of 400 μsec by an externally applied cathode-anode voltage. For total pressures in the range of 100 Torr, lasing action is observed to occur in single 50–400-μsec-wide pulses, depending upon the discharge parameters. Energy supplied by the sustainer is converted to laser output with an efficiency of approximately 7%.
Thermal self-defocusing of laser beams
Authors: Ghatak A.K. , Sharma S.K.
Published: January 2004

In this communication we have extended the theory of Akhmanov and his co-workers for thermal self-defocusing to include the effect of diffraction. The theory is also valid for large amounts of defocusing. Comparison has been made with the available experimental data.
``Noncritical'' phase matching in optical waveguides
Authors: Burns W.K. , Andrews R.A.
Published: January 2004

Phase matching of nonlinear three-wave optical processes in optical waveguides is shown to be possible with the use of only zero-order TE and TM modes, such that the phase-match condition is made insensitive to waveguide thickness over a limited region. This is accomplished by adjusting the phase shifts on total internal reflection for lowest-order modes, near cutoff, in a thin nearly symmetric waveguide. This ``noncritical'' situation eases the requirements on waveguide fabrication. Limitations due to bulk dispersion, waveguide asymmetry, and surface scattering losses are discussed.
On the theory of punch-through diodes
Authors: Vlaardingerbroek M.T. , van de Roer Th.G.
Published: January 2004

An analytical small-signal theory of punch-through diodes is presented in which both the dc and ac hole drift velocity depend on the local electric field. The negative resistance is caused by the velocity and space-charge modulation in the bulk of the n layer, which arise from the interaction of the holes with the electric field. The field dependence of the injection tends to decrease this negative resistance at low current densities.