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Showing papers in "Applied Physics Letters in 1969"


Journal ArticleDOI
TL;DR: Vapor deposited GaN single crystals tested for electrical and optical properties, determining band gap energy, electron concentration, etc as mentioned in this paper, were tested for testing the properties of single crystals.
Abstract: Vapor deposited GaN single crystals tested for electrical and optical properties, determining band gap energy, electron concentration, etc

1,211 citations


Journal ArticleDOI
TL;DR: In this article, the authors report theory and experiment on modes of propagating light waves in deposited semiconductor films, where the modes are excited by a prism-film coupler which is also used for the measurement of their phase velocities.
Abstract: We report theory and experiment on modes of propagating light waves in deposited semiconductor films. The modes are excited by a novel prism‐film coupler which is also used for the measurement of their phase velocities. Up to 50% of the incident laser energy has been fed into a single mode of propagation. The positions and linewidths of the modes, the wave intensity inside the film, and a dramatic view of the mode spectrum displayed by the scattered light are discussed in detail.

751 citations


Journal ArticleDOI
M. A. Duguay1, J. W. Hansen1
TL;DR: In this paper, a simple technique for gating light on and off on the picosecond time scale is described, which is built in much the same fashion as traditional Kerr cells, the difference lying in the use of powerful optical pulses rather than electrical pulses to induce a birefringence in various liquids.
Abstract: A simple technique is described for gating light on and off on the picosecond time scale. The gate is built in much the same fashion as traditional Kerr cells, the difference lying in the use of powerful optical pulses rather than electrical pulses to induce a birefringence in various liquids. The direct observation of the exponential decay (τ = 32 ± 6 psec) of the birefringence induced in nitrobenzene shows that orientational effects are largely responsible for the refractive index changes induced by light in this liquid.

394 citations


Journal ArticleDOI
TL;DR: In this article, a model for estimating effects due to electron scattering from grain boundaries, occurring simultaneously with background scattering, was developed for polycrystalline metal films in which a very fine-grained structure is often found.
Abstract: A model is developed for estimating effects due to electron scattering from grain boundaries, occurring simultaneously with background scattering. Since grain‐boundary effects are negligible in bulk materials, the model is particularly relevant to polycrystalline metal films in which a very fine‐grained structure is often found. It is shown by solution of the appropriate Boltzmann equation, that the total resistivity can be strongly dominated by grain‐boundary scattering. If grain size increases with film thickness, a marked dependence of resistivity on thickness exists, even when scattering from external surfaces is negligible or is completely specular.

393 citations


Journal ArticleDOI
TL;DR: In this article, a saturable resonator is used to switch out the CO2 laser light from its cavity and for repetitive Q•switching for variable length pulses, infinite length pulse trains, logical operations on two signals, and memory functions.
Abstract: Optical resonators containing saturable absorbers (saturable resonators) have nonlinear characteristics and can exhibit hysteresis. This is demonstrated experimentally at 10.6 μ wavelength. A saturable resonator is used to switch out the CO2 laser light from its cavity and for repetitive Q‐switching. Devices are described to obtain variable length pulses, infinite pulse trains, logical operations on two signals, and memory functions.

345 citations


Journal ArticleDOI
TL;DR: In this paper, the validity of the Kinchin-Pease formula is examined on the basis of recent progress in the theory of collision cascades and irradiation experiments on semiconductors and metals.
Abstract: The validity of the Kinchin‐Pease formula is re‐examined on the basis of recent progress in the theory of collision cascades and irradiation experiments on semiconductors and metals.

315 citations


Journal ArticleDOI
TL;DR: The appearance of phase contrast, Fresnel fringes and various forms of diffraction contrast in images produced by transmission scanning electron microscopes can be explained by invoking the principle of reciprocity to equate the imaging conditions to those relevant to a conventional electron microscope as discussed by the authors.
Abstract: The appearance of phase‐contrast, Fresnel fringes and various forms of diffraction contrast in images produced by transmission scanning electron microscopes can be understood simply by invoking the principle of reciprocity to equate the imaging conditions to those relevant to a conventional electron microscope.

264 citations


Journal ArticleDOI
TL;DR: In this article, Czochralski growth characteristics of a new laser host crystal, YAlO3, and measurements of its optical, thermal, and mechanical properties are reported.
Abstract: Czochralski growth characteristics of a new laser host crystal, YAlO3, and measurements of its optical, thermal, and mechanical properties are reported. Stimulated emission from Nd3+ in YAlO3 has been observed.

240 citations


Journal ArticleDOI
TL;DR: Raman backscatter of frequency doubled ruby laser beam by water vapor in atmosphere observed by optical radar, calculating water vapor mixing ratio profile profile as mentioned in this paper was used to calculate water vapor mixture profile.
Abstract: Raman backscatter of frequency doubled ruby laser beam by water vapor in atmosphere observed by optical radar, calculating water vapor mixing ratio profile

207 citations


Journal ArticleDOI
TL;DR: An Auger electron spectrometer for studies of solid surfaces which is considerably more sensitive than currently used instruments has been developed as mentioned in this paper, and greatly improved signal-to-noise ratio of the spectrometers made it possible to display the 0-1000 eV Auger spectrum on an oscilloscope at a scanning rate of 20 000 V/sec.
Abstract: An Auger electron spectrometer for studies of solid surfaces which is considerably more sensitive than currently used instruments has been developed. The greatly improved signal‐to‐noise ratio of the spectrometer made it possible to display the 0–1000 eV Auger spectrum on an oscilloscope at a scanning rate of 20 000 V/sec. Alternatively, the scanning rate may be reduced to that typical of present instruments (∼2 V/sec) and the primary beam current reduced from 5 × 10−5 to 10−8 A.

183 citations


Journal ArticleDOI
TL;DR: In this article, the authors showed that the R(127) line of the 11-5 band of molecular iodine at 633 nm has been observed by saturating the absorption inside the cavity of a single-frequency He-Ne laser.
Abstract: Hyperfine components of the R(127) line of the 11–5 band of molecular iodine at 633 nm have been observed by saturating the absorption inside the cavity of a single‐frequency He–Ne laser. The component widths of 4.5 MHz were broadened a factor of 2 by 1‐Torr iodine pressure, or by 500‐G magnetic field. Since no wavelength shift as large as 2 MHz was observed, wavelength perturbations from these sources should be controllable to less than 2 × 10−13λ. The use of one of these components as a reference for laser stabilization is suggested.

Journal ArticleDOI
TL;DR: In this paper, an experiment is described which confirms the theory of the distortion of a cholesteric structure by a magnetic field, and a sample of pazoxyanisole doped with cholesteryl acetate was viewed directly with a microscope.
Abstract: An experiment is described which confirms the theory of the distortion of a cholesteric structure by a magnetic field. Field effects in a sample of p‐azoxyanisole doped with cholesteryl acetate were viewed directly with a microscope, and the pitch of the helical structure was measured as a function of field strength.

Journal ArticleDOI
TL;DR: In this paper, a self-phase modulation with a dispersive delay line is used to obtain temporal compression of the pulse envelope, which exhibits a frequency sweep in the region of maximum intensity, the slope in time being proportional to the propagation distance.
Abstract: A frequency modulation which is monotonic in time over a portion of an optical pulse can be utilized together with a dispersive delay line to obtain temporal compression of the pulse envelope. Short pulses (picosecond range) passed through an optical Kerr liquid receive a self‐phase‐modulation which exhibits a frequency sweep in the region of maximum intensity, the slope in time being proportional to the propagation distance. Frequency spreads of the order of 103 cm−1 are obtainable and hence significant compression ratios should be possible, giving rise to very short pulses in the range of 10−14 to 10−13 sec.

Journal ArticleDOI
TL;DR: In this article, the first observation of tunable stimulated optical emission from a nonlinear crystal without the use of an external resonator, and with greater than 50% conversion of the pump beam to the tunable frequency was reported.
Abstract: We report the first observation of tunable stimulated optical emission from a nonlinear crystal without the use of an external resonator, and with greater than 50% conversion of the pump beam to the tunable frequency. Opposite faces of a LiNbO3 crystal were polished flat and parallel to provide for multiple reflections of the signal radiation (Stokes) inside the crystal. The A1 symmetry 248‐cm−1 polariton mode was excited with a Q‐switched ruby laser, and the signal frequency was tuned by varying the angle of incidence of the laser beam relative to the normal to the crystal surface. Operation was at room temperature; no crystal damage was observed over most of the tuning range; and laser depletion occurred within the first few nanoseconds of the Q‐switched pulse. The difference between the Stokes frequency and laser frequency was varied from 42 to 200 cm−1, and the corresponding idler wavelength was varied from 238 to 50 μ.

Journal ArticleDOI
TL;DR: In this paper, electron injection from p type silicon and hole injection from n type silicon by hot carrier emission have been observed to achieve average electron current densities as high as 10−2 A/cm2.
Abstract: Injection of carriers into thermally grown SiO2 from an avalanche plasma in silicon is a new way of achieving high current densities in SiO2. Electron injection from p‐type silicon and hole injection from n‐type silicon by hot carrier emission have been observed. Average electron current densities as high as 10−2 A/cm2 have been observed to flow through 1000 A of SiO2. The oxide becomes negatively charged as a result of electron injection and positively charged as a result of hole injection. These charging effects appear to be related to the presence of water in the oxide.

Journal ArticleDOI
TL;DR: In this paper, a photo-induced polymerization was used to record holograms with exposure of 1 to 30 mJ/cm2 at 0.694 μ, followed by rapid optical, dry processing with ultraviolet radiation.
Abstract: A photosensitive material based on photo‐induced polymerization has been used to record holograms. Exposure of 1 to 30 mJ/cm2 at 0.694 μ were followed by rapid optical, dry processing with ultraviolet radiation. Good resolution and diffraction efficiencies of up to 45% into the first order were observed.

Journal ArticleDOI
TL;DR: In this paper, the formation of a liquid phase and what appear to be conducting filaments have been observed and recorded, and current densities > 104 A cm−2 have been estimated in the filaments.
Abstract: Electrical switching in thin‐film As2SeTe2 semiconducting glass diodes with thin‐film electrodes has been studied. The formation of a liquid phase and what appear to be conducting filaments have been observed and recorded. Current densities > 104 A cm−2 have been estimated in the filaments.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the thermal emission rates of electrons and holes at the gold acceptor center (EC − EAu− = 550 mV) and of holes in the gold donor center (EAu+ − EV = 350 mV), respectively, in the temperature range of −160 to +100°C.
Abstract: Thermal emission rates of electrons and holes at the gold‐acceptor center (EC − EAu− = 550 mV) and of holes at the gold‐donor center (EAu+ − EV = 350 mV) are measured using the dark current, dark capacitance, and photocapacitance transient methods. About ten decades of the electron emission rate and eight decades of the hole emission rates are obtained in the temperature range of −160 to +100°C. The data correspond to electric fields of 104 and 105 V/cm maximum field in the p‐n junction and differ from the thermal equilibrium emission rates computed from previously published capture rate data at thermal equilibrium due to the field dependence of the capture rate from hot electron effect and of the emission rate from barrier lowering of the impurity potential.

Journal ArticleDOI
TL;DR: In this paper, the authors detected the production of divacancies in Si by 400-keV oxygen ion implantation (ΦI = 175 × 1014 cm−2, two sides) by the characteristic divacancy optical absorption band at 18 μ.
Abstract: The production of divacancies in Si by 400‐keV oxygen ion implantation (ΦI = 175 × 1014 cm−2, two sides) was detected by the characteristic divacancy optical absorption band at 18 μ This band has been previously correlated with the presence of divacancies in electron‐ and neutron‐irradiated silicon Ion‐produced divacancy annealing near 200°C was observed to correlate with neutron‐produced divacancy annealing Detailed comparisons of the annealing of electron‐, neutron‐, and ion‐produced divacancies suggest that the ion‐produced divacancies anneal primarily in regions with sink concentrations ≥ 1019 cm−3

Journal ArticleDOI
TL;DR: In this article, a two-stage (horizontal and vertical) acoustically driven light deflector is described, each stage has an 80MHz bandwidth and can deflect over 50% of an incident laser beam (5145 A) with less than 1 W of electrical drive power.
Abstract: Crystalline lead molybdate PbMoO4 has been found to be well suited for acousto‐optical device applications. This material has desirable properties similar to the previously reported α‐iodic acid α‐HIO3. However, PbMoO4, unlike α‐HIO3, is insoluble in water and can therefore be readily fabricated into devices and its optical surfaces do not require protection from the atmosphere. The elastic, photoelastic, optical, and thermal properties of PbMoO4 have been measured. These data have been used in the design of several acousto‐optic devices. An example consisting of a two stage (horizontal and vertical) acoustically driven light deflector is described. Each stage of this deflector has an 80‐MHz bandwidth and can deflect over 50% of an incident laser beam (5145 A) with less than 1 W of electrical drive power.

Journal ArticleDOI
TL;DR: In this article, the second harmonic of a Nd laser has been produced in LiIO3 in a phase matching direction of 30° to the c axis with high conversion efficiency.
Abstract: The second harmonic of a Nd laser has been produced in LiIO3 in a phase matching direction of 30° to the c axis with high conversion efficiency. The nonlinear optical coefficient t31 is among the highest so far reported for phase matchable substances using λ = 1.06 μ. LiIO3 can be grown from water solutions with excellent optical quality.

Journal ArticleDOI
TL;DR: In this article, the power conversion efficiency for green emission from BaYF5:Yb3+, Er3+ is equal to that for green emitting GaP diodes.
Abstract: Efficient infrared‐to‐visible conversion by Yb3+–Er3+ and Yb3+–Ho3+ ions in BaLuF5 and BaYF5 is reported. When pumped by radiation from a Si–GaAs diode, the power conversion efficiency for green emission from BaYF5:Yb3+, Er3+ is equal to that for green emitting GaP diodes.

Journal ArticleDOI
TL;DR: Laser harmonic-frequency mixing techniques extended into IR with IR metal-metal point contact diode as mentioned in this paper was used for IR laser harmonic frequency mixing with IR point contact diodes.
Abstract: Laser harmonic-frequency mixing techniques extended into IR with IR metal-metal point contact diode

Journal ArticleDOI
TL;DR: In this article, the electron energy distribution function has been calculated for the plasma of a CO2-N2-He mixture using available electron-molecule cross-section data, and the rates at which electrons transfer energy to the inelastic levels of CO2 and N2 were then determined.
Abstract: The electron energy distribution function has been calculated for the plasma of a CO2–N2–He mixture using available electron—molecule cross‐section data. Rates at which electrons transfer energy to the inelastic levels of CO2 and N2 were then determined. With this information, the relationship of the various electron—molecule energy exchange processes to laser performance was studied. For conditions typical of CO2 lasers, approximately 17% of the power transferred to the CO2 and N2 was found to be available for conversion to optical power. Estimates of maximum available optical power were made and found to be consistent with experimental values.

PatentDOI
John E. Bjorkholm1
TL;DR: In this paper, a singly resonant optical parametric oscillator (SRO) is used to tune a high power, pulsed source and tune it to a predetermined desired frequency, and radiation of that frequency is injected into a mode of the SRO from a stabilized, low power injection source.
Abstract: A singly resonant optical parametric oscillator (SRO) is pumped by a high power, pulsed source and is tuned approximately to a predetermined desired frequency. Radiation of that frequency is injected into a mode of the SRO from a stabilized, low-power injection source. The output of the SRO is a pulsed, high-power signal with frequency equal to the predetermined frequency to a high degree of accuracy.

Journal ArticleDOI
TL;DR: In this paper, a self-contained cw kW CO2 laser with a 1m active length and a 1.5m output power was measured as a function of flow velocity and electrical input power.
Abstract: Closed‐cycle gas cooling techniques have resulted in a self‐contained cw kW CO2 laser having a 1‐m active length. The CO2, N2, He gas mixture is recirculated through a heat exchanger following forced convection transverse to the optical cavity and the electrical discharge. Output power has been measured as a function of flow velocity and electrical input power.

Journal ArticleDOI
TL;DR: In this paper, potential probe and infrared microradiometer measurements reveal that the switching action takes place in a small region somewhere along a path of devitrified material, and application of voltage pulses can move this region to a different position.
Abstract: Switching phenomena take place in thick bulk samples of semiconducting glass, once a path of devitrified material is established. Potential probe and infrared microradiometer measurements reveal that the switching action takes place in a small region somewhere along this path. Application of voltage pulses can move this region to a different position. Evidence of partial devitrification and melting is also found in thin film switches made from many different glass compositions. Memory switching has also been observed in all bulk and thin film experiments to date. Since the characteristics of bulk and thin film switching are remarkably similar, doubt is cast upon the interpretation of switching phenomena as due to electronic properties of amorphous semiconductors.

Journal ArticleDOI
TL;DR: In this paper, a simple relation between the applied electric field and optical exposure is determined which allows electrical control of optically induced refractive index change, which can also be used to control diffraction efficiency of the holographic reconstruction process.
Abstract: Single‐crystal Sr0.75Ba0.25Nb2O6 when used in conjunction with an externally applied electric field is shown to be a sensitive volume holographic medium capable of high‐resolution information storage. Optically induced refractive index changes of 5 × 10−4 have been observed with laser exposure of 14 J/cm2. A simple relation between the applied electric field and optical exposure is determined which allows electrical control of optically induced refractive index change. In addition to control of the optically induced effect it is found that the applied electric field can also be used to control the diffraction efficiency of the holographic reconstruction process.

Journal ArticleDOI
TL;DR: Pulses of 500psec duration, emitted by a mode-locked He-Ne laser, have been electro-optically frequency swept and then compressed to 270 psec by multiple reflections from an interferometer proposed by Gires and Tournois as mentioned in this paper.
Abstract: Pulses of 500‐psec duration, emitted by a mode‐locked He–Ne laser, have been electro‐optically frequency swept and then compressed to 270 psec by multiple reflections from an interferometer proposed by Gires and Tournois.

Journal ArticleDOI
TL;DR: In this article, the mechanisms relating to infrared-pumped visible and ultraviolet emission observed from Yb3+−Er3+ and Yb 3+−Ho3+ ions in BaYF5 and Y3OCl7 (reported in the companion papers) are discussed.
Abstract: The mechanisms relating to infrared‐pumped visible and ultraviolet emission observed from Yb3+–Er3+ and Yb3+–Ho3+ ions in BaYF5 and Y3OCl7 (reported in the companion papers) are discussed. An analysis is given of the material parameters required for efficient conversion and the limiting performance which can be expected from a near ideal material is indicated.