Showing papers in "Applied Physics Letters in 1972"
TL;DR: In this article, backward stimulated Brillouin scattering (SBS) in glass optical fibers has been observed with less than 1 W of input power at 5355 A. Experimental results are compared with theory, and the implied limitation to optical fiber transmission is discussed.
Abstract: Observations of backward stimulated Brillouin scattering (SBS) in glass optical fibers are reported. Threshold for SBS has been achieved with less than 1 W of input power at 5355 A. Relaxation behavior in the SBS signal has also been observed and is attributed to finite‐cell‐length oscillation. Experimental results are compared with theory, and the implied limitation to optical fiber transmission is discussed.
655 citations
TL;DR: In this paper, a new magnetic material which has the highest saturation magnetization at room temperature, 2050 G, among those of all the magnetic materials was attributed to Fe16N2, which has a bct structure, and the magnetic moment associated with Fe atoms of Fe 16N2 was deduced to be 3.0 μB.
Abstract: The change of the saturation magnetization of Fe films with the pressure of nitrogen during deposition ranging from 2 × 10−5 to 7 × 10−3 Torr has been investigated systematically. We found a new magnetic material which has the highest saturation magnetization at room temperature, 2050 G, among those of all the magnetic materials. This was attributed to Fe16N2, which has a bct structure, and the magnetic moment associated with Fe atoms of Fe16N2 was deduced to be 3.0 μB.
573 citations
TL;DR: Vacuum-deposited films have been used in substrate preparation for liquid-crystal cells as mentioned in this paper to provide an oriented surface for alignment of nematic liquid crystals far better than the well-known ''rubbed'' plate.
Abstract: Vacuum‐deposited films now replace the familiar ``rubbing'' process in substrate preparation for liquid‐crystal cells. Films deposited at an angle provide an oriented surface for alignment of nematic liquid crystals far better than the well‐known ``rubbed'' plate. The oblique deposit causes a film growth in a preferred direction, which results in a ``sympathetic alignment'' of the nematic liquid crystals when applied.
558 citations
TL;DR: In this article, a glass fiber optical waveguide was used for the construction of wide-band fiber amplifiers and Raman oscillators tunable over a range of 100 A. Even though the Raman cross section is quite small, relatively low threshold for Raman emission can be achieved because high optical power densities are maintained over long lengths of waveguide.
Abstract: Stimulated Raman emission in the visible has been observed in glass‐fiber optical waveguides. Even though the Raman cross section is quite small, relatively low threshold for Raman emission can be achieved because high optical power densities are maintained over long lengths of waveguide. The broad stimulated gain bandwidths available in glass should permit the construction of wide‐band fiber amplifiers and Raman oscillators tunable over a range of 100 A.
412 citations
TL;DR: In this article, the infrared-pumped visible luminescence of NaYF4 : Yb, Er was studied and shown to have at least twice the visible output of YF3: Yb, Er when pumped with a narrow-band excitation source at the optimum frequency.
Abstract: Studies of the infrared‐pumped visible luminescence of NaYF4 : Yb, Er show it to have at least twice the visible output of YF3 : Yb, Er when pumped with a narrow‐band excitation source at the optimum frequency. It is also free from saturation effects until very intense excitation levels are reached. The mechanism for red upconversion appears to change with increasing excitation from a two‐step process to one involving a significant amount of three‐step upconversion, which change is accompanied by an increase in the response time for visible emissions.
279 citations
TL;DR: In this article, a stable continuous output of picosecond pulses has been achieved using second-harmonic generation (SHG) measurements, and the pulses are transform limited and are wavelength tunable over the range 5900-6100 A.
Abstract: Passive mode locking of a cw Rhodamine 6G laser is reported. A stable continuous output of picosecond pulses has been achieved. Correlation measurements using second‐harmonic generation (SHG) have determined the pulses to be as short as 1.5 psec. The pulses are transform limited and are wavelength tunable over the range 5900–6100 A.
259 citations
TL;DR: In this paper, a ruby laser has been operated in the circular TE01 mode by means of a novel mode selector, and the output characteristics, conversion into TM01, and possible applications are described.
Abstract: A ruby laser has been operated in the circular TE01 mode by means of a novel mode selector. Construction, output characteristics, conversion into TM01, and possible applications are described.
234 citations
TL;DR: In this paper, a low-loss waveguide for integrated optical devices is described. But the guiding region is located beneath the substrate glass and the transmission loss of the waveguides is estimated to be less than 0.1 dB/cm.
Abstract: Low‐loss waveguides for integrated optical devices are formed by electrically induced migration of ions in glass plates. The guiding region is located beneath the substrate glass. The transmission loss of the waveguides is estimated to be less than 0.1 dB/cm.
222 citations
TL;DR: In this article, the authors demonstrated that phase holograms in ferroelectric materials can be achieved by fast electrical control, using an external field slightly smaller than the coercive field to the crystal.
Abstract: We have demonstrated that fixation and erasure of phase holograms in ferroelectric materials can be achieved by fast electrical control. High ionic mobility that allows the change of the electronic pattern into a stable ionic one is obtained by applying, during 0.1 sec, an external field slightly smaller than the coercive field to the crystal. Erasure is accomplished in 3 sec by applying a field that causes saturation of the polarization. Investigation of this process was carried out in BaTio3 crystals doped with Fe.
208 citations
TL;DR: In this paper, the authors report the first time switching and modulation of light in a magneto-optic waveguide that is a single-crystal epitaxially grown iron-garnet film.
Abstract: We report for the first time switching and modulation of light in a magneto‐optic waveguide that is a single‐crystal epitaxially grown iron‐garnet film. These experiments involve the Faraday rotation of the magnetic film and the motion of magnetization in the plane of the film. We have modulated light from a 1.152‐μm laser up to 80 MHz. We were also able to switch light between two waveguide modes by applying a magnetic field as small as 0.2 Oe.
170 citations
TL;DR: The GaN and InN thin films were grown on sapphire, silicon, and metallic substrates using rf sputtering at temperatures of 25 −750°C and presputtering vacuum of 10−8 Torr.
Abstract: GaN and InN thin films were grown on sapphire, silicon, and metallic substrates using rf sputtering at temperatures of 25–750°C and presputtering vacuum of 10−8 Torr. The GaN films were high in resistivity (> 108 Ω cm), but the InN layers were highly conducting with an electron concentration of 7×1018 cm−3. The refractive index for GaN ranged from 2.1 to 2.4 at long wavelengths and was dispersive below 8000 A; the index for InN is higher, 2.9. The absorption coefficient was measured from wavelengths of 2 μ to 2000 A.
TL;DR: In this paper, the authors used backscattering of MeV He ions to investigate the composition and growth kinetics of metal silicides formed from thin films of Pd, Ti, Cr, and Mo evaporated onto Si.
Abstract: Backscattering of MeV He ions has been used to investigate the composition and growth kinetics of metal silicides formed from thin films of Pd, Ti, Cr, and Mo evaporated onto Si. In each system studied, one silicide phase predominated (Pd2Si, TiSi2, CrSi2, and MoSi2). The thickness of the phase increased with (time)0.5 for Pd2Si and TiSi2, and linearly in time for CrSi2 and MoSi2. It was found that these two time dependencies correlate directly with the reaction sensitivity to a thin oxide interface (<100 A) and to the extent of the silicide formation in the neighborhood of a typical device contact region.
TL;DR: In this article, an optical waveguide was produced in n-type GaAs by implantation with 300-keV protons, and the guiding was due to the elimination of charge carriers from the implanted region.
Abstract: We have produced optical waveguides in n‐type GaAs by implantation with 300‐keV protons. The guiding is shown to be due to the elimination of charge carriers from the implanted region. Annealing of the waveguide leads to very large reductions in the 1.15‐μ guided‐wave absorption.
TL;DR: In this paper, an electron-beam-controlled discharge has been used to pump a variety of CO2 laser gas mixtures at atmospheric pressure in substantial volumes, and the electrical and laser properties of the pumped medium have been measured.
Abstract: An electron‐beam‐controlled discharge has been used to pump a variety of CO2 laser gas mixtures at atmospheric pressure in substantial volumes. Electrical and laser properties of the pumped medium have been measured. Small‐signal‐gain coefficients up to 0.045 cm−1 were achieved at field strengths of 3 kV/cm.
TL;DR: In this paper, the authors measured the ratio d36(GaP)/d11(SiO2) = 185 ± 10% at 1.318 µm and determined a better set of absolute values for the nonlinear susceptibility.
Abstract: We have measured the ratio d36(GaP)/d11(SiO2) = 185 ± 10% at 1.318 μ. By using this value together with other values in the literature, we determine a better set of absolute values for the nonlinear susceptibility.
TL;DR: In this paper, the VUV emission characteristics of Xenon for pressures from 15 to 450 psi were presented, with and without mirrors, and the mean radiative lifetime was 2×10−8.
Abstract: Vacuum ultraviolet (VUV) emission characteristics of xenon for pressures from 15 to 450 psi are presented. Stimulated emission was observed above 200 psi. Experiments were run both with and without mirrors. Without mirrors, the emission was 150 A wide centered at 1700 A, and the mean radiative lifetime was 2×10−8. The energy conversion efficiency was ∼ 20%. With mirrors above 200 psi the emission width narrowed to 17 A centered at 1716 A, and the output was highly directional. The pulse width narrowed from 50 to ∼ 3 nsec.
TL;DR: In this paper, a high-repetition rate optical pulse generator which employs a Fabry-Perot electro-optic modulator as the output coupler of a laser resonator was constructed.
Abstract: A high‐repetition‐rate optical pulse generator which employs a Fabry‐Perot electro‐optic modulator as the output coupler of a laser resonator was constructed. Using this generator with a He–Ne 6328‐A laser tube, 21‐psec optical pulses at a repetition rate of 2.7 × 109 pps were experimentally obtained with an average power level of 0.5 mW. In addition, it is demonstrated that the width of the pulses obtained from this generator can be narrowed without regard to the gain‐linewidth limitation. This kind of pulse generator may be particularly useful for obtaining short optical pulses from low‐gain gas lasers, and it is possible to obtain 1010‐pps picosecond pulses from a He–Ne 6328‐A laser.
TL;DR: In this paper, two step-tunable CO2 lasers were used for phase matched generation of submillimeter wave radiation for high-resolution spectroscopy using a ternary semiconductor, ZnGeP2.
Abstract: Using two step‐tunable CO2 lasers, we have observed phase‐matched generation of frequencies 70 <ν<110 cm−1 by nonlinear mixing in a birefringent ternary semiconductor, ZnGeP2. An observed power of ∼1.7 μW at 83.37 cm−1 gave a signal‐to‐noise ratio of ∼1000 with a Ge:Ga detector. In combination with tunable optical lasers, this technique should yield a tunable source of submillimeter wave radiation for high‐resolution spectroscopy.
TL;DR: Water vapor absorption lines in the ν2 band involving transitions between states of high rotational energy have been found to undergo substantial collisional narrowing in the presence of buffer gases as discussed by the authors.
Abstract: Water‐vapor absorption lines in the ν2 band involving transitions between states of high rotational energy have been found to undergo substantial collisional narrowing in the presence of buffer gases. Measurements were carried out near 5.35 μm, using tunable lead sulfide selenide semiconductor diode lasers.
TL;DR: In this paper, the phenomenon of ruby laser-induced breakdown in liquids is investigated by high-speed holography, and the advantage of using holographic instead of ordinary photography lies in the possibility to easily suppress the bright white light emitted during the breakdown process.
Abstract: The phenomenon of ruby laser‐induced breakdown in liquids is investigated by high‐speed holography. The advantage of using holography instead of ordinary photography lies in the possibility to easily suppress the bright white light emitted during the breakdown process. This light constitutes an incoherent background on the holographic plate and does not reproduce upon reconstruction of the recorded scene.
TL;DR: In this article, the authors report light-wave propagation experiments in singlecrystal epitaxially grown garnet films, and discuss refractive index and lattice constant considerations for various garnets, and also the use of iron and gallium garnet substrates as magneto-optical waveguides useful in integrated optics.
Abstract: We report light‐wave propagation experiments in single‐crystal epitaxially grown garnet films. The discussion includes refractive index and lattice constant considerations for various garnets, and also the use of iron garnet films on gallium garnet substrates as magneto‐optical waveguides useful in integrated optics.
TL;DR: In this article, the spatial arrangement of the two sets of misfit dislocations in an orthogonal array is observed, and the effect of this asymmetry has been observed in compositionally graded crystals of In1−xGaxP and GaAs 1−xPx grown from vapor phase.
Abstract: Symmetry considerations reveal that an asymmetry exists relative to orthogonal 60° dislocations of the same sign in zinc‐blende structure. The effect of this asymmetry has been observed in compositionally graded crystals of In1−xGaxP and GaAs1−xPx grown from vapor phase. It is observed that the spatial arrangement of the two sets of misfit dislocations in an orthogonal array is different. In one 〈110〉 direction, the misfit dislocations tend to be uniformly distributed, while in the other 〈110〉 direction there is a marked tendency for periodic banding of the dislocations.
TL;DR: In this paper, the authors realized a high switching speed Si S-shaped negative-resistance diode having a thin MIS structure where the thickness of the SiO2 layer is less than 100 A.
Abstract: We have realized a high‐switching‐speed Si S‐shaped negative‐resistance diode having a thin MIS structure where the thickness of the SiO2 layer is less than 100 A. It has a p‐n‐I (insulator)‐M (metal) structure in contrast with a Shockley diode. The threshold and sustaining voltages are about 20 and 2–3 V, respectively. The regenerative nature of this device may be related to the minority carrier injection into the interface between the n layer and the insulating layer, and electron trapping in the interface states.
TL;DR: In this article, an asymmetric dielectric light guide with a metal-film outer coating was used to select TE0 mode selection in an Asymmetric Dielectric Light Guide.
Abstract: TE0 mode selection was observed in an asymmetric dielectric light guide with a metal‐film outer coating. TM0 mode and higher‐order modes could not transmit through the guide, whereas the loss of the TE mode, the insertion loss, was small. The experimental data were in good agreement with the theoretical results given here. Filter action is explained by modal repulsion from the metal wall that is inherent in an asymmetric guide.
IBM1
TL;DR: In this paper, a homojunction solar cell consisting of pGa1−xAlxAs−pGaAs-n GaAs was used to achieve power conversion efficiency of over 16% (corrected for contact area) measured in sunlight for air mass 1 at sea level, while efficiencies of 19-20% for an air mass value of 2 or more.
Abstract: Heterojunction solar cells consisting of pGa1−xAlxAs–pGaAs–n GaAs are grown by liquid‐phase epitaxy and exhibit power conversion efficiencies of over 16% (corrected for contact area) measured in sunlight for air mass 1 at sea level, while efficiencies of 19–20% are obtained for an air mass value of 2 or more. The improved efficiencies compared to conventional homojunction (Si and GaAs) cells are attributed to the reduction of series resistance and the reduction of surface recombination losses resulting from the presence of the heavily doped Ga1−xAlxAs layer. Open‐circuit voltages of 0.98–1.0 V and short‐circuit currents of 18–21 mA/cm2 (corrected for contact area) are observed for a solar input intensity of 98.3 mW/cm2.
TL;DR: In this article, a technique for measuring the velocity of a circular magnetic domain in a magnetic field gradient is described, which has been applied to epitaxial garnet films, and results are presented for a film of nominal composition Eu1Er2Ga0.7Fe4.3O12.
Abstract: A technique for measuring the velocity of a circular magnetic domain in a magnetic field gradient is described. The method has been applied to epitaxial garnet films, and results are presented for a film of nominal composition Eu1Er2Ga0.7Fe4.3O12. The technique is compared with other methods of measuring domain wall mobility.
TL;DR: In this paper, the authors achieved spatially uniform tunable birefringence with negative dielectric anisotropy materials using a unique previously unreported molecular configuration at zero field, where molecules align with their long axes at a small angle to the sample normal.
Abstract: Spatially uniform birefringences tunable over the range 0. 0–0. 15 for applied voltages less than 20 V rms and with a sharp threshold below 4 V rms are obtained for thin layers of nematic liquid crystals with negative dielectric anisotropy. The achievement of spatially uniform tunable birefringence with negative‐dielectric‐anisotropy materials requires a source of in‐plane anisotropy which is provided by a unique previously unreported molecular configuration at zero field. At V=0, the molecules align with their long axes at a small angle to the sample normal. The experimental results are analyzed in terms of a continuum model and experimental values obtained for the relevant elastic constants.
TL;DR: In this paper, a non-crystalline Ge film was obtained by sputtering on to various substrates, which crystallizes with "explosive" velocities when triggered by a localized transient energy pulse.
Abstract: We report herein the preparation of a form of noncrystalline Ge film by rf sputtering on to various substrates, which crystallizes with ``explosive'' velocities when triggered by a localized transient energy pulse. The films show this phenomenon only when they are thicker than about 10 μ. The crystallization wave appears to be acoustically transmitted.
TL;DR: In this article, a flashlamp-pumped cresyl-violet dye laser has been mode locked to produce picosecond pulses (3-5 psec) frequency tunable from 644 to 704 nm.
Abstract: Employing polymethine dyes as saturable absorbers and intracavity Fabry‐Perot interferometers, a flashlamp‐pumped cresyl‐violet dye laser has been mode locked to produce picosecond pulses (3–5 psec) frequency tunable from 644 to 704 nm. The frequency tuning ranges of mode‐locked rhodamine 6G and rhodamine B dye lasers have also been extended to cover 584 to 645 nm.
TL;DR: In this article, high-frequency small-signal capacitances of semiconductor junction vs temperature, from the initial conditions of filled and emptied traps in the junction depletion region, are used to determine the trap concentration and the thermal activation energies of trapped electrons and holes.
Abstract: High‐frequency small‐signal capacitances of semiconductor junction vs temperature, from the initial conditions of filled and emptied traps in the junction depletion region, are used to determine the trap concentration and the thermal activation energies of trapped electrons and holes. Illustrations are given for silicon N + P diodes doped with gold impurity or irradiated with 1‐MeV electrons, showing the room‐temperature annealing for the latter.