bluuebunny/crossref_metadata_2025 huggingface dataset:
A helium-mercury direct nuclear pumped laser
Authors: Akerman M. A. , Miley G. H. , McArthur D. A.
Published: February 2003

A 6150-Å He-Hg laser, pumped solely by the 1n (10B,α) 7Li nuclear reaction, has been achieved using the Sandia SPRII reactor. The optimum conditions for lasing were 600 Torr total pressure with 2.5 mTorr Hg partial pressure, with a threshold for lasing of ∼1016 n/cm2 sec. This is the first visible-wavelength laser having nuclear energy as its only source of excitation.
CF4 and NOCl molecular lasers operating in the 16-μm region
Authors: Tiee Joe J. , Wittig Curt
Published: February 2003

We have obtained stimulated emission in the 16-μm egion from CF4 and NOCl with an optical pumping scheme which uses a single CO2 TEA laser as the excitation source. Measured laser energies from CF4 and NOCl are 4 and 3 mJ, respectively, which represents an order-of-magnitude improvement over exisiting molecular lasers oscillating in this region. There appear to be no fundamental limitations to scaling these lasers to energies ⩾1 J. These lasers offer considerable promise for the laser isotope separation of uranium.
A SAW bandpass filter technique using a fanned multistrip coupler
Authors: Solie Leland P.
Published: February 2003

A SAW filter is described which uses multistrip couplers with diferent periodicities in two adjacent tracks in order to transfer a surface wave from one track to the other over a restricted frequency band, i.e., to filter the signal. The principal advantage is good filtering with low insertion loss. Over 30-dB out-of-band rejection with 3-dB loss in the fanned multistrip coupler at a frequency of 216 MHz is demonstrated.
Defect production in copper and silver by light energetic ions
Authors: Averback R. S. , Benedek R. , Merkle K. L.
Published: February 2003

Measurements have been made of the change in residual electrical resistivity in thin-film specimens of Cu and Ag induced by light-ion irradiations (H,D,3He, 4He) below 10 K in the energy range 15–40 keV. The number of Frenkel pairs created per incident ion was deduced and compared with theoretical predictions. The efficiency factor (ratio of experimental to theoretical value) was found to decrease from ∼1 to 0.7 (0.9 to 0.65) for Cu (Ag) as the recoil spectrum was shifted to higher energies by increasing the projectile mass and/or energy.
Passive ring resonator laser gyroscope
Authors: Ezekiel S. , Balsamo S. R.
Published: February 2003

A new method of measuring inertial rotation is presented. It is based on the use of a passive ring resonator as the rotation sensing element and an external laser for measuring the difference between the clockwise and counterclockwise lengths of the resonator. Preliminary performance data is included.
Elimination of stress-induced birefringence effects in single-crystal high-power laser windows
Authors: Joiner R. E. , Marburger J. , Steier W. H.
Published: February 2003

Wave-front distortion caused by stress-induced birefringence can be eliminated in certain single-crystal high-power laser windows by properly orienting the crystal. Experimental results for BaF2 are reported.
Saturated optical nonresonant emission spectroscopy (SONRES) for atomic detection
Authors: Gelbwachs J. A. , Klein C. F. , Wessel J. E.
Published: February 2003

We have demonstrated the extremely small detection limits that can be achieved in a high-pressure environment by the combination of saturated absorption and nonresonance emission spectroscopy. The method of SONRES exploits efficient energy transfer between excited atomic states at high pressures and intense optical fields available from tunable lasers. An estimated 104 atoms/cm3 of sodium were monitored in a flame; the corresponding atomic concentration was 1 part in 1015. A detection limit of ∼10 atoms/cm3 was recorded for sodium in argon. The ultimate detection limit for this method is ∼10−4 atoms.
Optical attenuation in pure and doped fused silica in the ir wavelength region
Authors: Izawa T. , Shibata N. , Takeda A.
Published: February 2003

Infrared absorption spectra of GeO2-, P2O5-, and B2O3-doped fused silica and nondoped fused silica have been obtained in the 3–25-μm wavelength region. It is shown that the intrinsic infrared absorption loss of doped silica fiber increases by several orders of magnitude beyond 1.8–2.0 μm because of the overtone and combination tone vibrations of the SiO4 tetrahedron. The loss spectrum is affected by dopants, especially in the case of B2O3. The lower limit of attenuation in optical fiber is estimated to be about 0.2 dB/km at 1.6 μm.
cw optically resonance pumped transfer laser in DF-CO2 system
Authors: Wang John H. S. , Finzi Jack , Mastrup F. N.
Published: February 2003

An optically pumped cw 10.6-μm DF/CO2 transfer laser has been demonstrated. This has been accomplished by exciting a 3 cm × 0.3 cm transfer laser medium, consisting of a 1 : 19 : 80 DF/CO2/He flowing gas mixture at 22 torr and room temperature, with a 70-Watt multiline chemical DF laser. In the preffered ’’intracavity’’ configuration where the transfer-laser medium was located in between the DF-laser resonator mirrors, 1.5 W of 10.6-μm power was outcoupled. This power corresponds to a photon conversion efficiency of available DF-pump flux to outcoupled transfer-laser flux of 6%. Analysis predicts that multiline DF laser-to-single-line CO2 photon conversion efficiencies exceeding 90% should be attainable in an optimized apparatus configuration.
The photoinduced Rayleigh scattering in BaTiO3 crystals showing the bulk photovoltaic effect
Authors: Chanussot G. , Fridkin V. M. , Godefroy G. , Jannot B.
Published: February 2003

In BaTiO3 crystals possessing bulk photovoltaic behavior a photoinduced polarized Rayleigh scattering was observed. The results show that illumination of BaTiO3 crystals creates an inhomogeneous distribution of spontaneous polarization (photofluctuations) which are responsible for both effects, the bulk photovoltaic effect and the polarized Rayleigh scattering. The pseudo-Jahn-Teller effect which was introduced earlier for other photoferroelectric phenomena is assumed to be responsible for the creation of these photoinduced fluctuations.
Pt2Si and PtSi formation with high-purity Pt thin films
Authors: Canali C. , Catellani C. , Prudenziati M. , Wadlin W. H. , Evans C. A.
Published: February 2003

Formation rates of Pt2Si and PtSi have been measured using 1.8-MeV 4He+ backscattering spectroscopy. Both silicide layers were grown with t1/2 time dependence, but the formation of PtSi starts only after all available Pt has reacted for the formation of Pt2Si, in disagreement with previously reported results. The activation energies have the common value 1.5±0.1 eV. Auger electron spectroscopy data confirmed the deposited Pt film purity and show that the contaminants contained in the sputter-deposited Pt layer segregate at the Pt2Si/Pt interface. It is postulated that this interfacial impurity buildup can affect the formation rate of Pt2Si and the further evolution of the system.
Fluorescence-activated liquid-crystal display
Authors: Baur G. , Greubel W.
Published: February 2003

By combination of a liquid-crystal light valve with a simple additional device, a great brightness intensification of the displayed digits is achievable solely by efficient use of ambient light. In a plastic plate, doped with fluorescent molecules, ambient light is collected, guided, and finally emitted at the digit segments. Promising experimental results have been obtained.
Calculation of recombination rate constants for KrF*+R+R →RKrF*+R (R=Ar, Kr)
Authors: Shui Ven H.
Published: February 2003

The recombination of KrF*+R+R→RKrF*+R (R=Ar, Kr) has been modelled. The rate constants calculated by using the classical phase-space theory are kr(Ar) =9×10−32 cm6/sec and kr(Kr) =5×10−31 cm6/sec.
Spectroscopic observation of fast ions from laser-produced plasmas
Authors: McLean E. A. , Decoste R. , Ripin B. H. , Stamper J. A. , Griem H. R. , McMahon J. M. , Bodner S. E.
Published: February 2003

Using a time-of-flight spectroscopic technique, measurements were made of the ion energy distributions of very fast ions and thermal ions produced when a 7–15-J 100-psec Nd : glass laser pulse (1.06 μm) strikes a (CH2)n slab target. Ion energies greater than 0.5 MeV have been observed for the first time with this technique of measurement. A simultaneous comparison is made between the signal of an ion charge collector placed 30 cm from the target and the intensity of the C VI 3434-Å ion line at 1 cm from the target.
Radiation-enhanced outdiffusion of xenon implanted in aluminum
Authors: Wittmaack K. , Blank P.
Published: February 2003

Entrapment of 10–160-keV xenon implanted under UHV conditions in polycrystalline aluminum has been investigated by Rutherford backscattering. The saturation xenon distributions were found to be strongly affected by radiation-enhanced outdiffusion. Different from silicon the loss of xenon from near-surface regions of aluminum increases with increasing ion energy. The results are explained in terms of spike-activated diffusion.
Observation of a nonlinear photoacoustic signal with potential application to nanosecond time resolution
Authors: Rockley Mark G. , Devlin J. Paul
Published: February 2003

Preliminary experimental results are reported which demonstrate the application of photoacoustic spectroscopy to the measurement of excited-state absorption spectra with nanosecond time resolution.
Generation of near-infrared picosecond pulses by mode-locked synchronous pumping of a jet-stream dye laser
Authors: Kuhl J. , Lambrich R. , von der Linde D.
Published: February 2003

Picosecond pulses continuously tunable from 685 to over 900 nm have been obtained from a dye laser synchronously pumped by a mode-locked krypton laser. The pulse duration was measured by autocorrelation techniques to be as short as 25 ps. Conversion efficiency up to 30% and average power in excess of 400 mW were observed. Continuous-wave laser operation for three new dyes between 870 and 985 nm is also reported.
Selective absorption of solar energy in ultrafine chromium particles
Authors: Granqvist C. G. , Niklasson G. A.
Published: February 2003

Ultrafine chromium particles prepared by evaporation in argon + air are found to be highly absorbing over the solar spectrum and highly transparent in the infrared. Such spectral selectivity is the distinctive feature of a coating in an efficient photothermal converter for solar energy. Optical transmittance through coatings with mass density ≲0.5 g/m2 agrees well with calculations based on the Maxwell-Garnett theory, whereas coatings with larger mass density exhibit a transmittance too low to be directly reconciled with this theory.
A search for interface states in an LPE GaAs/AlxGa1−xAs heterojunction
Authors: Lang D. V. , Logan R. A.
Published: February 2003

We have used the DLTS capacitance spectroscopy technique to search for interface states associated with an LPE GaAs/Al0.22Ga0.78As heterojunction. The results can be interpreted in terms of well-known deep bulk states shifting abruptly at the interface with no observable interface states. The limiting values are <5×108 and <4×109 cm−2 interface states (deeper than 0.1 eV) in the upper and lower half of the gap, respectively.
A monolithic zinc-oxide–on–silicon p-n-diode storage correlator
Authors: Tuan H. C. , Kino G. S.
Published: February 2003

A monolithic zinc-oxide–on–silicon p-n storage correlator has been constructed. When operated both as a convolver and as a storage correlator, the electronic efficiency obtained with this device is comparable to that of the present LiNbO3 airgap devices. This device has the potential of having very large dynamic range because of the absence of spurious bulk-wave generation, as occurs in the airgap device. Several signal-processing functions have been demonstrated with this new type of storage correlator. In one chirp correlation experiment, correlation of signals with a time-bandwith product of 4000 has been observed.
Infrared four-wave mixing in liquid CO
Authors: McNair R. E. , Klein M. B.
Published: February 2003

Four-wave mixing of the type ω4 = 2ω1 − ω2 has been observed in pure liquid CO at 77 °K. The CO2 pump beams were derived from separate resonators to yield a mixing signal at 8.64 μm. The power dependence of the mixing signal has been studied over four orders of magnitude and the nonlinear susceptibility has been measured. Scaling calculations show that efficiencies greater than 10% are expected for pump powers near the breakdown threshold and with confinement of the pump beams in a hollow dielectric waveguide.
Direct conversion of CO2 laser energy to high-voltage electrical energy using a laser-produced plasma
Authors: Silfvast W. T. , Szeto L. H.
Published: February 2003

High-voltage high-current pulses of electrical energy (700 V, 14 A, 10 kW) are generated with efficiencies greater than 0.1% for a duration of 30 nsec when a 3–4-J CO2 TEA laser is focused on a copper cathode in a special vacuum cell designed to collect the ejected high-energy electrons. Potential applications as a high-voltage source and as a detector are discussed.
Mode-locking characteristics of a neodymium-glass laser using the polymethine dye No. 3955 in a solid host
Authors: Taylor J. R. , Sibbett W. , Cormier A. J.
Published: February 2003

A neodymium-phosphate glass oscillator mode locked using the saturable absorber dye No. 3955 in a plastic host has been shown to give completely modulated outputs. Single pulses of duration ∼5 psec with the low background have been obtained, when operating close to threshold. The aperature time of the dye in the plastic host was measured to be 130±25 psec.
Improved heterostructure-laser light-output linearity by antireflective coating
Authors: Miller R. C. , Joyce W. B.
Published: February 2003

An antireflective coating is shown to raise the kink (abrupt nonlinearity in the light-current relation) in (Al,Ga)As laser output by a factor of at least 2 or 3 in optical power before an appreciable increase in threshold current is incurred. This observation is consistent with the assumption that the kink occurs at a given optical power within the laser rather than at a given emitted power.
The magnetostatic surface-wave propagation in a corrugated YIG slab
Authors: Tsutsumi Makoto , Sakaguchi Yasunori , Kumagai Nobuaki
Published: February 2003

An analysis for the propagation characteristics of the magnetostatic surface waves in a YIG slab having periodically corrugated surfaces is presented. The Brillouin diagrams, close to the intersection point (ω,β) of m=0 and m=−1 space harmonics, are obtained for different strengths of modulation. Comparison between the magnetostatic surface waves and volume waves concerning the complex value of the propagation constant within the stop band is also discussed.
Oblique incidence of magnetostatic waves on a metallic grating
Authors: Owens J. M. , Collins J. H. , Smith C. V. , Chiang I. I.
Published: February 2003

Experiments in the 3-GHz region are reported for oblique incidence of magnetostatic forward volume waves (MSFVW) on an 8-period uniform metallic grating of 140 μm periodicity. The MSFVW propagate in a 25-μm-thick epitaxial yttrium iron garnet film under normal magnetic bias. Insertion loss data and observed bandpass response are reasonably consistent with theory for MSFVW reflection through 90° by an array possessing a periodic impedance discontinuity.
High-speed camera investigation of CO2 TEA laser discharges
Authors: Sakai Y. , Sakamoto S. , Tagashira H. , Maeda S.
Published: February 2003

Glow formation and glow-to-arc transition processes of moderate-volume atmospheric-pressure discharge in a CO2 laser gas mixture with and without external ultraviolet volume preionization are studied optically by an image-converter-intensifier camera. Three typical types of photographs for (i) glow and arc formation with preionization, (ii) glow formation only with preionization, and (iii) glow and arc formation without forming network. Discharge development is compared, and dominant factors to suppress arc formation of relevance to designing CO2 TEA lasers are discussed.
A general two-dimensional theory for volume holograms
Authors: Solymar L.
Published: February 2003

Coupled partial differential equations are derived for the amplitude of the electric field in a general two-dimensional volume hologram. Nonuniform amplitude distributions, nonplanar wave fronts, losses, and non-Bragg incidence are considered both for dielectric and absorption gratings. The formulation is in holographic terminology but the equations are valid for weakly modulated Bragg devices in general.
A pulser-sustainer carbon monoxide electric-discharge supersonic laser
Authors: Monson Daryl J. , Srinivasan G.
Published: February 2003

Operation of a cw CO electric-discharge supersonic laser with a pulser-sustainer discharge is described. High-power operation as well as independent control over electron energy and density are demonstrated. Maximum input power achieved to date is 100 kW. The maximum output power is 6 kW or 10% of the sustainer positive column power. Much improved performance appears possible.
Trace-gas analysis with a resonant optoacoustic cell operating inside the cavity of a CO2 laser
Authors: Shtrikman S. , Slatkine M.
Published: February 2003

An intracavity optoacoustic trace-gas analyzer is described and performance tests for ethylene are given. The analyzer uses a tunable CO2 laser and a resonant optoacoustic cell of novel design with high immunity to window interference and suitable for measurements under flow conditions. The resonant cell can also be operated with no windows at all. The sensitivity of the windowless analyzer to gas absorption is below 10−7 cm−1 for 1-Hz bandwidth detection. It is estimated that by reduction of the laser’s internal losses, the measurable absorption can be lowered to 3×10−10 cm−1.
Ga(1−x)AlxAs/Ga(1−y)AlyAs double-heterostructure room-temperature lasers grown by metalorganic chemical vapor deposition
Authors: Dupuis R. D. , Dapkus P. D.
Published: February 2003

Room-temperature operation of Ga(1−x)AlxAs/Ga(1−y)AlyAs double-heterostructure lasers grown by metalorganic chemical vapor deposition (MO-CVD) has been achieved. These devices have Ga(1−y)AlyAs active layers of 0.8≲y≲0.12 and emit in the wavelength range 8000<λ<8300 Å. Broad-area Fabry-Perot lasers with pulsed threshold current densities as low as ∼1.2 kA/cm2 have been fabricated. These lasers are produced from five-layer epitaxial structures grown entirely by the MO-CVD process and are the first such devices to be fabricated from materials grown by a vapor-phase process.
Effects of implantant depth distribution on photoluminescence spectra in Be-implanted GaAs
Authors: Bishop S. G. , Comas J. , Sundaram S. , McCombe B. D.
Published: February 2003

Photoluminescence spectra from ion-implanted Be acceptors in GaAs have been studied as a function of wavelength and intensity of excitation light over the implant-fluence range 3×1012 to 1×1015 cm−2. It is demonstrated that the nonuniform distributions of implantant concentration as a function of depth in the implanted layer produce a profiling effect which causes anomalous changes in photoluminescence line shapes and energy positions as a function of excitation intensity. These results imply photoexcited carrier diffusion lengths of much less than 1 μm in implanted and annealed layers in bulk GaAs.
High-field critical current in i
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i
t
u multifilamentary Cu-Sn-Nb alloys
Authors: Foner S. , McNiff E. J. , Schwartz B. B. , Roberge R. , Fihey J. L.
Published: February 2003

High-field properties of improved in situ Cu-Sn-Nb alloys are presented. Values of critical current densities of 104 A/cm2 and a resistivity of less than 2×10−13 Ω cm are observed at 12 T. Critical current densities for various in situ alloys are presented for fields to 18 T.
Large-optical-cavity GaAs- (GaAl)As injection laser with low-loss distributed Bragg reflectors
Authors: Namizaki Hirofumi , Shams Mohammad Kazem , Wang Shyh
Published: February 2003

A large-optical-cavity injection laser with low-loss distributed Bragg reflectors has been realized. The temperature dependence of threshold current and of lasing wavelength clearly showed the DBR mode of operation. At room temperature, the lowest threshold current density thus far achieved was 7 kA/cm2. A coupling coefficient of around 50 cm−1 was estimated from the spectral bandwidth and from the intensity distribution of light scattered from the DBR region.
Coherent coupling of radiation to metal-barrier-metal structures by surface plasmons
Authors: Siu D. P. , Gustafson T. K.
Published: February 2003

It is shown that the coherent coupling of radiation into metal-barrier-metal structures by surface plasmons, which reduces to the usual antenna coupling at low frequencies, can be efficient up to a frequency at least as high as the plasma resonance.
Evaluation of the threshold voltage for short-channel MOSFET’s
Authors: Nishida Masanori
Published: February 2003

It has been well known that in a long-channel MOSFET, the experimental value of the threshold voltage obtained by the square-root extrapolation method in the saturation region agrees well with the theoretical criterion. In a short-channel MOSFET, the so-determined threshold voltage depends on the drain voltage because of the drain current dependence on the drain voltage VDS. In this letter, a new method to determine the threshold voltage for VDS=0 V will be discussed.
Low-noise millimeter-wave mixer diodes prepared by molecular beam epitaxy (MBE)
Authors: Schneider M. V. , Linke R. A. , Cho A. Y.
Published: February 2003

Schottky barrier diodes which are specifically designed for use in cryogenically cooled millimeter-wave mixers have been fabricated from MBE layers grown on heavily doped GaAs substrates. At 15 K the devices show a nearly exponential current-voltage characteristic and a diode noise temperature which is determined predominantly by the tunneling transport mechanism. A diode noise temperature as low as 55 K was achieved under pumped conditions. This is the lowest diode noise temperature ever obtained in a resistive mixer. A single sideband mixer noise temperature of 315 K was measured at 102 GHz for a cryogenic mixer employing these diodes.
Measurement of hydrogen depth distribution by resonant nuclear reactions
Authors: Barnes C. A. , Overley J. C. , Switkowski Z. E. , Tombrello T. A.
Published: February 2003

The resonance at E (19F) =6.42 MeV in the reaction 1H(19F,αγ)16O has been explored as a potentially useful method for the quantitative determination of hydrogen concentration as a function of depth in a solid substrate. The relative merits of this resonance, the 16.44-MeV resonance in the same reaction, and the 6.39-MeV resonance in the reaction 1H(15N,αγ)12C are discussed.
Gain and absorption measurements in a KrF* laser
Authors: Hawryluk A.M. , Mangano J. A. , Jacob J. H.
Published: February 2003

The small-signal gain and absorption of an electron-beam-excited KrF* laser mix was measured by probing the excited medium with a frequency-doubled flashlamp-pumped dye laser. The mixture contained 0.3% F2, 6% Kr, and 93.7% Ar. The doubled dye laser was used to determine the single-pass gain or loss of this e-beam-excited mixture over the KrF* (2Σ1/2 →2Σ1/2) emission band. The KrF* and other relevant excited-state number densities under the condition of the experiment were determined from a comprehensive kinetic model. The effective KrF* stimulated-emission cross section was determined by dividing the measured gain per centimeter on line center by the excited-state number density.
Flash-lamp-excited NdP5O14 laser
Authors: Chinn S. R. , Zwicker W. K.
Published: February 2003

A simple miniature room-temperature pulsed NdP5O14 laser excited by a small Xe flash lamp has been made, with threshold energies of a few hundred millijoules. Output energies of 1.5 mJ have been obtained with less than 1 J input, and an order-of-magnitude improvement is expected.
Bandwidth-limited picosecond pulses from a neodymium-phosphate glass oscillator
Authors: Taylor J. R. , Sibbett W. , Cormier A. J.
Published: February 2003

Direct measurements using a picosecond streak camera have shown that transform-limited pulses having durations ∼5 psec are produced throughout the pulse train of a mode-locked neodymium-phosphate glass laser operating in the TEM00 mode. Under the conditions of higher-power multimode operation, bandwidth-limited pulses are generated in the initial part of the train only. Spectral and temporal broadening due to intensity-dependent nonlinear effects are observed as the higher-power mode-locked trains evolve.
Transient versus steady-state molecular absorption: Application to CO2 laser pulse-duration discrimination
Authors: Feldman B. J. , Fisher Robert A. , McLellan E. J.
Published: February 2003

Transmission of short CO2 laser pulses in heated CO2, including pulse reshaping and ringing, is studied using single-sweep oscilloscope-detector combination having a 100-psec rise time. We demonstrate that hot CO2 is extremely effective in increasing by as much as 1000-fold the pulse-to-background intensity ratio in short-pulse CO2 laser systems.
Use of the optoacoustic effect to discover cw far-infrared laser lines
Authors: Busse B. , Thurmaier R.
Published: February 2003

Two cw far-infrared laser lines in optically pumped CH3CHF2 have been discovered by use of the optoacoustic effect. Our method is based on the observation that narrow maxima in the spectrophone output signal of a molecular gas are found for emission lines of a cw CO2 laser which pump the gas optically to far-infrared laser action.
Pinhole imaging of fast ions from laser-produced plasmas
Authors: Slater D. C.
Published: February 2003

Pinhole-camera images formed by fast ions emitted from spherical-glass-shell targets uniformly irradiated by intense 1.06-μm laser light have been recorded on cellulose-nitrate films. The spatial resolution of the images is consistent with the 5- and 9-μm pinhole size. The size of the image relative to the target size provides the first measurement of the angular distribution of fast-ion emission from spherical targets. The observed images indicate a forward-peaked distribution, but with very broad angular spread. Image sizes increase with laser intensity and pulse length.
The origin of large dark spots in AlxGa1−xAs-GaAs heterostructure photoluminescence
Authors: Henry C. H. , Logan R. A.
Published: February 2003

Large dark spots are explained in terms of current flow in heterojunctions and surface recombination. A theory of the photoluminescence line shape is presented and verified by experiment.
Submillimeter-wave laser operating in a passive Q-switched intracavity pump mode
Authors: Koepf Gerhard A.
Published: February 2003

Pulsed operation of submillimeter gas lasers was achieved with the laser gas inside the resonator of the CO2 pump laser acting as a saturable absorber for passive Q switching the CO2 laser. With a metal-oxyde-metal whisker detector 1–5-μs-wide pulses could be detected at 118, 373, and 496 μm wavelength.
Broad-band grating filters for thin-film optical waveguides
Authors: Hong C. S. , Shellan J. B. , Livanos A. C. , Yariv A. , Katzir A.
Published: February 2003

Broad-band grating filters have been fabricated on glass thin-film waveguides and evaluated with a tunable dye laser. Measured and calculated filter responses were found to be in good agreement. Grating filters with bandwidths of 300 and 150 Å, and reflectivities of 18 and 40%, respectively, are reported.
Rapid oxygen diffusion in Ca-doped yttrium iron garnet films at 25 to 250 °C
Authors: LeCraw R. C. , Gyorgy E. M. , Pierce R. D. , Nielsen J. W. , Blank S. L. , Miller D. C. , Wolfe R.
Published: February 2003

Unexpectedly rapid oxygen diffusion has been observed at 25–250 °C in YIG films with uncompensated Ca additions of 0.1 to 0.23 atoms per formula unit. A 3-μm-thick film originally dark and conducting due to Fe4+ lightened and became insulating in 15 min at 100 °C in a reducing saturated solution of FeCl2. A diffusion distance of ∼0.5 mm has been observed along a film in 25 h at 250 °C. A model is proposed based on the dependence of the diffusion coefficient D on oxygen vacancy concentration. A magnetic bubble garnet film containing Ca, which also lightened at 250 °C, showed no observable changes in the pertinent bubble parameters.
Reversible conductivity changes in discharge-produced amorphous Si
Authors: Staebler D. L. , Wronski C. R.
Published: February 2003

A new reversible photoelectronic effect is reported for amorphous Si produced by glow discharge of SiH4. Long exposure to light decreases both the photoconductivity and the dark conductivity, the latter by nearly four orders of magnitude. Annealing above 150 °C reverses the process. A model involving optically induced changes in gap states is proposed. The results have strong implications for both the physical nature of the material and for its applications in thin-film solar cells, as well as the reproducibility of measurements on discharge-produced Si.
Prebreakdown phenomena in sphere-sphere electrode configurations in dielectric liquids
Authors: Devins John C. , Rzad Stefan J. , Schwabe Robert J.
Published: February 2003

Negative streamer growth is observed in a highly refined mineral oil for sphere-sphere electrode configurations. The shape of the streamers is somewhat different from that found in point-plane geometries. The addition of electron trapping additives accelerates the negative streamer velocity as was found to be the case in point-plane geometry. Breakdown occurs before the negative streamer crosses the gap and appears to originate at the anode. Very fast positive streamers are, in fact, observed.
High-power millimeter radiation from an intense relativistic electron-beam device
Authors: Marshall T. C. , Talmadge S. , Efthimion P.
Published: February 2003

Several megawatts of radiation at wavelength as short as 1 mm have been generated by the interaction of an intense relativistic electron beam with a rippled magnetic field.
Structure and initial oxidation of the LaB6 (001) surface
Authors: Aono M. , Tanaka T. , Bannai E. , Kawai S.
Published: February 2003

The LaB6 (001) clean surface and its initial oxidation have been studied by UPS, XPS, and work-function measurements. For the clean surface, a so-called surface state has been found, and a work function of 2.4±0.1 eV has been measured. The surface state disappears by an oxygen exposure of ∼7 langmuir (L), and the work function increases up to 4.0±0.1 eV. This initial oxidation is not a simple oxygen-adsorption process but proceeds with the formation of a surface oxide or oxides.
Offset masks for lift-off photoprocessing
Authors: Dolan G. J.
Published: February 2003

We describe a technique using photolithography to produce submicron-scale thin-film structures and simple multilevel structures by single-mask lift-off processing. The technique employs masks offset from the substrate and oblique angle thin-film deposition. It provides a simple means of making small-area Josephson junctions and varying-thickness superconducting bridges and is suitable for the inclusion of these devices in circuits. The examples we show emphasize such applications in superconductivity; however, the technique may find uses in other fields as well.
Interstitial oxygen gettering in Czochralski silicon wafers
Authors: Rozgonyi G. A. , Pearce C. W.
Published: February 2003

A procedure for reducing the interstitial oxygen content of virgin Czochralski silicon wafers is described. The process consists of oxidizing wafers in an HCl-added dry oxygen ambient. The gettering action reduces the probability of oxygen precipitation throughout the bulk of the wafer and simultaneously provides a masking or passivating surface oxide. Since oxygen precipitates have been correlated with the nucleation of dislocations and stacking faults, which are known to adversely affect many devices, these gettering procedures may provide a means for overcoming some of the processing problems associated with large-diameter high oxygen content Czochralski material.
Tunable blue picosecond pulses from a dye laser
Authors: Cox A. J. , Scott Gary W. , Talley Larry D.
Published: February 2003

Blue picosecond length pulses have been produced by a short-cavity dye laser, axially pumped with the third harmonic of a mode-locked Nd+3 : glass laser. Tuning was conveniently achieved by tilting the laser. Performance was investigated for cavity lengths ranging from 10 to 150 μm.
Soft x-ray spectroscopy of an imploding aluminum liner Z pinch
Authors: Burns E. J. T. , Degnan J. H. , Reinvovsky R. H. , Baker W. L. , Clark M. C. , McClenahan C. W.
Published: February 2003

We report the first detailed x-ray spectroscopic data from a fast (1.1 μsec) high-energy (400 kJ) implosion of an aluminized formvar liner. The high-energy (≳1 keV) x-ray data indicate a 400-eV electron temperature and a 3×1020 cm−3 electron density. These parameters pertain to the highest-energy component of the radiation spectrum.
Optical phase conjugation in a lithium formate crystal
Authors: Avizonis P. V. , Hopf F. A. , Bomberger W. D. , Jacobs S. F. , Tomita A. , Womack K. H.
Published: February 2003

Optical phase reversal has been demonstrated using type-II phase matching in lithium formate operated as a degenerate optical parametric amplifier with pump peak powers as low as 103 W. The amplifier was driven in a collimated geometry.
Charge separation and target voltages in laser-produced plasmas
Authors: Pearlman J. S. , Dahlbacka G. H.
Published: February 2003

Measurement of the voltages of isolated targets irradiated with 50-psec laser pulses show kilovolt target potentials existing for many nanoseconds. The amplitude of the voltage exceeds what is normally expected for a plasma pressure gradient by roughly an order of magnitude. The voltage amplitude and temporal characteristics are found to be dependent on the vacuum chamber dimensions. A simple one-dimensional plasma model explains the voltage characteristics through the existence of space-charge separation effects and leads to a measurement of the plasma temperature.
Optical properties of selectively absorbing Ni/Al2O3 composite films
Authors: Craighead H. G. , Buhrman R. A.
Published: February 2003

Composite films of Ni particles embedded in an Al2O3 matrix have been produced by controlled coevaporation. The optical properties of the Ni/Al2O3 composites measured over the range of the solar spectrum are in good accord with the predictions of Maxwell-Garnett theory provided the Ni volume fraction is ≲0.2. The composite films have excellent spectral selectivity for the absorption of solar radiation, with a solar absorptivity of 0.94 obtained for a film produced with a composition gradient. Low-temperature emissivities of ∼0.1 have been obtained with composite films evaporated on highly reflecting metal substrates.
An infrared upconverter for astronomical imaging
Authors: Boyd R. W. , Townes C. H.
Published: February 2003

An imaging upconverter has been constructed which is suitable for use in the study of the thermal 10-μm radiation from astronomical sources. The infrared radiation is converted to visible radiation by mixing in a 1-cm-long proustite crystal. The phase-matched 2-cm−1 bandpass is tunable from 9 to 11 μm. The conversion efficiency is 2×10−7, and the field of view of 40 arc seconds on the sky contains several hundred picture elements, approximately diffraction-limited resolution in a large telescope. The instrument has been used in studies of the sun, moon, Mercury, and VY Canis Majoris.
Green HgCl(B2Σ+→X2Σ+) laser
Authors: Eden J. Gary
Published: February 2003

Lasing action on the v=0→v′=22 transition of the B2Σ+→X2Σ+ band of HgCl has been observed. Electron beam excitation of Ar/Xe/Hg/CCl4 or CCl3Br mixtures produced oscillation at 557.62 and 558.35 (±0.15) nm. The mercury-halide family appears promising as an efficient source of line-tunable stimulated emission in the blue-green region of the spectrum.
AlyGa1-yAs-AlxGa1-x as laser structures for integrated optics grown by molecular-beam epitaxy
Authors: Reinhart F. K. , Cho A. Y.
Published: February 2003

Taper-coupled lasers (TCL) suitable for integrated optical circuits were fabricated with molecular-beam epitaxy (MBE) by using bakable Ta masks. These lasers had an active layer thickness, d=0.3 μm, and a room-temperature threshold current density, jth, as low as 2.9 kA/cm2. The quality of this modified MBE growth also permitted construction of MBE lasers from the homogeneous passive AlyGa1-yAs waveguide sections for the first time. Such lasers with y=0.08 and d=0.8 μm oscillated at jth=9 kA/cm2 and a wavelength λ=0.83 μm. This result indicates the feasibility of developing a visible laser grown by MBE.
A new approach for the floating-gate MOS nonvolatile memory
Authors: Lee Han-Sheng
Published: February 2003

A nonavalanche injection method to charge the floating gate of the poly-silicon stacked-gates MOS memory device is proposed. The operation principle is based on the fact that the oxide thermally grown on poly-silicon is more conductive than the oxide thermally grown on single-crystal silicon. Measurement results of the test devices on writing and erasing ability and charge retentivity are presented.
Laser-target retropulse isolation using an aperture in vacuum
Authors: Benjamin R. F. , Henderson D. B. , Mitchell K. B. , Stroscio M. A. , Thomas J.
Published: February 2003

The plasma created near an aperture in vacuum is found to be an effective retropulse isolator for CO2 laser light. The plasma created by a subjoule CO2 beam remains overdense at least 50 ns after the CO2 pulse.
Instability of a low-pressure Na–noble-gas discharge
Authors: van Gemert M. J. C. , Verbeek T. G.
Published: February 2003

A new type of discharge instability is reported for a low-pressure Na–noble-gas discharge (∼5×10−3 Torr Na; 5.5 Torr Ne-Ar, 1% Ar). The voltage-current (V-I) characteristic is shown to be multivalued in the voltage. The resulting instability is a discontinuity in the positive column which propagates in the direction of electron particle flow with velocity between about 105 and 5×105 cm/s.
Amorphous threshold switch response to pulse burst waveforms
Authors: Reinhard D. K.
Published: February 2003

The switching response of thin-film amorphous chalcogenide threshold switches to pulse bursts of sine waves and square waves is reported. For the waveforms and devices investigated, preswitching behavior as evidenced by the delay time is a function of the rms voltage applied to the device. Switching voltages were slightly greater than the minimum required for switching.
SIMS evaluation of contamination on ion-cleaned (100) InP substrates
Authors: Dowsett M. G. , King R. M. , Parker E. H. C.
Published: February 2003

Recent work has indicated that residual contamination on III-V substrates has an adverse effect on epilayer nucleation. This letter presents preliminary results of measurements of contamination levels on methanol-bromine polished ion-cleaned (100) InP substrates using low [primary ion dose (<5×1012 ions mm−2) secondary ion mass] spectrometry (SIMS). Even after ion etching ≃0.48 μ from the surface residual contamination levels in the 100-ppm range persist, the largest being oxygen. Micrographs of the ion-cleaned surface showed precipitation of In at the surface which was caused by differential sputtering effects.
Narrowband detection at long wavelengths with epitaxial PbySn1−ySe films
Authors: Schoolar R. B. , Jensen J. D.
Published: February 2003

Narrowband photovoltaic detectors were prepared using two PbySn1−ySe epitaxial layers of slightly different alloy compositions grown on BaF2 substrates. Using Pb to form Schottky barrier detectors has yielded devices with D*λ (10.6 μm) =7.0×1010 cm Hz1/2 W−1 and spectral half-bandwidths of 6000 Å. These devices are insensitive to variations in incident angle due to the large refractive indices of PbySn1−ySe.
The effect of gas-phase stoichiometry on deep levels in vapor-grown GaAs
Authors: Miller M. D. , Olsen G. H. , Ettenberg M.
Published: February 2003

A deep (0.82 eV) impurity level has been observed via transient capacitance measurements in GaAs prepared under various gas-phase stoichiometries. The density of these impurities increased with increasing AsH3/GaCl ratio in the vapor phase ranging from 2×1013 cm−3 for a 1/3 ratio to 9×1013 cm−3 for a 3/1 ratio. The minority-carrier lifetime in these same samples decreased from 15 to 5 nsec with increasing AsH3/GaCl ratio. These deep levels, which serve as recombination centers for lifetime reduction, appear to originate from point defects introduced by deviations from stoichiometry toward the As-rich side.
Microscale degradation in (GaAl)As double-heterostructure diode lasers
Authors: Kato Daisuke
Published: February 2003

The generation of self-sustained pulsations in degraded (GaAl)As double-heterostructure diode lasers is explained by invoking microscale absorption centers possessing a large cross section. The microscale degradation centers are found to affect the laser characteristics at a concentration level as low as 1014–1015 cm−3.
Photoionization of metastable rare-gas atoms (He*,Ne*,Ar*,Kr*,Xe*)
Authors: McCann K. J. , Flannery M. R.
Published: February 2003

Cross sections σ for the photoionization of metastable rare-gas atoms (He*-Xe*) over a wide range of photon energies are presented. In marked contrast to that found for He* where σ∼10−18 cm2 and decreases monotonically with photon energy, the cross sections σ for Ne*-Xe* are much smaller ∼10−19 cm2 and exhibit optical windows within the wavelength range 2000–3000 Å of current laser interest.
Fast optically controlled modulator for a CO2 laser using two-photon magnetoabsorption effects in CdS
Authors: Nguyen V. T. , Damen T. C. , Gornik E. , Patel C. K. N.
Published: February 2003

We report the use of the two-photon magnetoabsorption effects due to excitons in CdS to obtain a fast modulator for a CO2 laser beam. The modulator is controlled by short optical pulses from a visible-light dye laser. 4-nsec pulses of 75 W peak power of a CO2 laser beam have been produced by using this technique which is potentially capable of generation of psec optical pulses in the infrared.
The study of laser processes by millimeter and submillimeter microwave spectroscopy
Authors: De Lucia Frank C.
Published: February 2003

Millimeter and submillimeter microwave spectroscopy is shown to be a powerful technique for the study of the fundamental processes of molecular lasers. The calculation of absolute chemical compositions, excitation parameters, and the observation of collisional deexcitation are demonstrated for the HCN FIR laser.
Room-temperature interfacial reaction in Au-semiconductor systems
Authors: Hiraki A. , Shuto K. , Kim S. , Kammura W. , Iwami M.
Published: February 2003

Au(evaporated film) -semiconductor(substrate) systems were studied by Auger electron spectroscopy. For semiconductors with energy gaps (Eg) smaller than ∼2.5 eV, even at room temperature a considerable fraction of atoms constituting the semiconductors were found to accumulate on the surfaces of Au films, indicating ready interfacial interaction between these materials. Study of the interface regions of the above systems verified the occurrence of the room-temperature interfacial reactions.
Highly collimated broadside emission from room-temperature GaAs distributed Bragg reflector lasers
Authors: Ng W. , Yariv A.
Published: February 2003

Highly collimated laser beams have been observed to be coupled out by second-order Bragg scattering from GaAs distributed Bragg reflector lasers. The beams are perpendicular to the waveguide plane and have an angular width of less than 1°. The diodes have a separate confinement structure and operate at room temperature with thresholds as low as 1.4 kA/cm2.
Acoustoelectric SAW phase shifter
Authors: Crowley J. D. , Weller J. F. , Giallorenzi T. G.
Published: February 2003

A new acoustoelectric phase shifter is proposed which produces a direct phase shift of a SAW on piezoelectric substrate. Computations of the attenuation and phase lag versus resistivity due to a silicon wafer air-gap coupled to yz-LiNbO3 are presented. The use of the variation of the resistivity of the silicon to control the phase of a SAW was demonstrated using the photogeneration of carriers and the field-effect control of the surface resistivity. A 180° shift was obtained with a +30-V transverse voltage pulse.
Reflection spectrum distortion due to Bragg-frequency variation in tapered highly reflective surface-wave gratings
Authors: Cross P. S.
Published: February 2003

The normal-incidence reflection spectrum of a tapered highly reflective (∼95%) surface-wave grating is found experimentally and theoretically to have high sidelobes due to the taper-induced spatial variation in the local Bragg frequency. In order to successfully use tapering for reflection sidelobe suppression, the Bragg-frequency variation is compensated by varying the grating period. Experimental results are presented for the reflection of surface acoustic waves from metal dot arrays on yz-LiNbO3 at ∼145 MHz. The taper-induced distortion of the reflection spectrum is expected to occur in corrugated optical waveguide reflectors as well.
A critical temperature for the growth of SiC on Si and its effect on stacking-fault nucleation in Si homoepitaxy in high vacuum
Authors: Smith F. W. , Meyerson B. , Miller W.
Published: February 2003

During a study of the homoepitaxial growth of Si on Si(111), we have found that stacking-fault densities in the deposited Si films decreased by two to three orders of magnitude above a ’’critical’’ substrate deposition temperature, 1250 °C. Nucleation of stacking faults in the deposited films is correlated, via SEM observations and infrared absorption measurements, with the presence of SiC protuberances on the substrate surface. We propose a simple model for SiC cluster growth (and decay) which explains the rapid decrease with temperature of the amount of SiC formed on the Si surface.
Superconducting properties of powder metallurgically produced Cu-Nb3Sn composite wires
Authors: Bormann R. , Schultz L. , Freyhardt H. C.
Published: February 2003

In this investigation we report on superconducting properties of in situ formed multifilamentary Cu-Nb3Sn composites produced by a powder-metallurgical technique. The wires contain 10 wt% Nb in Cu–1 wt% Sn and consist of discontinuous superconducting filaments embedded in a normal-conducting matrix. They can carry resistanceless currents exceeding 105 A/cm2 (at zero field and 4.2 K). The critical current density depends strongly on the reduction of the cross section by wire drawing, the annealing temperature, and the tin content. The superconducting properties of these wires are uniform and insensitive to bending.
The relative Raman cross sections of vitreous SiO2, GeO2, B2O3, and P2O5
Authors: Galeener F. L. , Mikkelsen J. C. , Geils R. H. , Mosby W. J.
Published: February 2003

We report the relative HH Raman spectra obtained from high-purity bulk samples of the primary glass formers SiO2, GeO2, B2O3, and P2O5. With 514.5-nm excitation, the peak Raman cross sections of these glasses have relative strengths of 1, 9.2, 4.7, and 5.7, respectively. The superior scattering strength of the latter three glasses suggests that they be used for increasing the gain and tuning range of fiber Raman lasers. The Raman spectra of mixed glasses containing GeO2, P2O5, and Na2O (or K2O) indicate that lasers made of these or similar materials may be continuously tunable over a range of 1300 cm−1.
Interchain ordering in amorphous solid polyethylene
Authors: Yoda Osamu , Kuriyama Isamu , Odajima Akira
Published: February 2003

The degree of interchain packing in solid polyethylene (PE) amorphized by γ irradiation has been analyzed by the x-ray diffraction method. The differential radial distribution function (DRDF) of amorphous PE has revealed that the short-range order in interchain packing exists as wide as 20 Å, which depends, however, slightly on the dose of irradiation. Parseval’s relation has proved the adequacy of the DRDF obtained.