Showing papers in "Applied Physics Letters in 1973"
TL;DR: Theoretical calculations supported by numerical simulations show that utilization of the nonlinear dependence of the index of refraction on intensity makes possible the transmission of picosecond optical pulses without distortion in dielectric fiber waveguides with group velocity dispersion.
Abstract: Theoretical calculations supported by numerical simulations show that utilization of the nonlinear dependence of the index of refraction on intensity makes possible the transmission of picosecond optical pulses without distortion in dielectric fiber waveguides with group velocity dispersion. In the case of anomalous dispersion (∂2ω/∂k2>0) discussed here [the case of normal dispersion (∂2ω/∂k2<0) will be discussed in a succeeding letter], the stationary pulse is a ``bright'' pulse, or envelope soliton. For a typical glass fiber guide, the balancing power required to produce a stationary 1‐ps pulse is approximately 1 W. Numerical simulations show that above a certain threshold power level such pulses are stable under the influence of small perturbations, large perturbations, white noise, or absorption.
2,509 citations
TL;DR: In this article, the transport properties of a finite superlattice from the tunneling point of view have been computed for the case of a limited number of spatial periods or a relatively short electron mean free path.
Abstract: 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.
1,996 citations
TL;DR: In this article, the small signal Raman gain in a single-mode glass waveguide amplifier has been measured directly and the measured gain is in good agreement with that calculated from the Raman cross section.
Abstract: The small signal Raman gain in a single‐mode glass waveguide amplifier has been measured directly. The measured gain is in good agreement with that calculated from the Raman cross section. The cross section was determined by a comparison of the spontaneous Raman scattering of fused quartz and benzene.
620 citations
TL;DR: In this paper, it has been shown that perpendicular uniaxial anisotropy and compensation points in the vicinity of room temperature can be obtained in amorphous thin films of rare earth transition metal alloys.
Abstract: It has been demonstrated that perpendicular uniaxial anisotropy and compensation points in the vicinity of room temperature can be obtained in amorphous thin films of rare‐earth—transition‐metal alloys. The magneto‐optic properties of these films are reported, and it is shown that a remarkably good signal‐to‐noise ratio can be obtained in a thermomagnetically written film.
360 citations
TL;DR: In this article, it was shown that Niobium-germanium (Nb3Ge) superconducting up to 22.3 K can be obtained by a high pressure dc sputtering process.
Abstract: Niobium‐germanium films which remain superconducting up to 22.3 K have been prepared by a high‐pressure dc sputtering process. The high Tc's of these films are attributed to the formation of a more nearly perfect stoichiometric Nb3Ge compound than has previously been obtainable.
345 citations
TL;DR: In this paper, the germanium output mirror of a TEA CO2 laser shows a periodicity of 10.6 μm, the laser wavelength, and an interference mechanism is proposed in which scattered and cavity radiation interfere.
Abstract: Damage in the germanium output mirror of a TEA CO2 laser shows a periodicity of 10.6 μm, the laser wavelength. A mechanism is proposed in which scattered and cavity radiation interfere. An interference mechanism is confirmed by experiments outside of the laser cavity. Periodic damage is obtained in thin films irradiated at angles other than the normal where the fringe spacing is modified.
344 citations
TL;DR: In this article, the nature and origin of the defects responsible for the rapid degradation of stripe geometry GaAs-GaAlAs double-heterostructure lasers have been identified by transmission electron microscopy.
Abstract: The nature and origin of the defects responsible for the rapid degradation of stripe geometry GaAs–GaAlAs double‐heterostructure lasers have been identified by transmission electron microscopy. These defects are formed by a three‐dimensional dislocation network which originates at a dislocation crossing the GaAlAs and GaAs epilayers. The propagation of the dislocation network takes place by a climb mechanism induced by the operation of the device.
302 citations
TL;DR: In this paper, a silane surface coupling agent is used to obtain chemically stable interfaces and a wide variety of liquid-crystal orientations, which are then used for orientation determination.
Abstract: Uniformly oriented thin liquid‐crystal layers are required for most liquid‐crystal device applications and physical investigations. Usual methods for obtaining orientation rely on a substrate interface which has an orienting action on the liquid‐crystal molecules. In previously described methods the orienting interfaces degrade chemically with time, thereby generating a corresponding degradation of the liquid‐crystal orientation. In the present work, silane surface coupling agents are used to obtain chemically stable interfaces and a wide variety of liquid‐crystal orientations.
293 citations
TL;DR: In this paper, positive refractive index layers in LiNbO3 and LiTaO3 have been produced by a novel out-diffusion technique, and the index profiles for a variety of conditions are measured directly with an interference microscope.
Abstract: Positive refractive‐index layers in LiNbO3 and LiTaO3 have been produced by a novel out‐diffusion technique. The index profiles for a variety of conditions are measured directly with an interference microscope. Low‐loss optical waveguiding on the surface of these crystals has been observed.
293 citations
TL;DR: In this article, a very sensitive method for gas concentration measurements is proposed, where intense light scattering is obtained through a stimulated interaction, which appears more practical than spontaneous Raman scattering for gas flow analysis with fine spatial resolution.
Abstract: A novel and very sensitive method for gas concentration measurements is proposed. Intense light scattering is obtained through a stimulated interaction. The method appears more practical than spontaneous Raman scattering for gas flow analysis with fine spatial resolution. Experimental results with the detection of H2 are given.
289 citations
TL;DR: In this article, the first demonstration of channel optical waveguide directional couplers was reported, where the closely spaced channel waveguides were fabricated in GaAs by proton implantation and optical coupling was observed at 1.15 μ with complete light transfer out of the initial channel into adjacent channels in lengths of typically 2 mm.
Abstract: We report the first demonstration of channel optical waveguide directional couplers. The closely spaced channel waveguides were fabricated in GaAs by proton implantation. Optical coupling was observed at 1.15 μ with complete light transfer out of the initial channel into adjacent channels in lengths of typically 2 mm.
TL;DR: In this paper, the authors measured the barrier heights of Au/n−InxGa1−xAs diodes by capacitancevoltage and saturation current methods, and obtained a low barrier height with a relatively wide band gap.
Abstract: The barrier heights φB of Au/n‐InxGa1−xAs diodes are measured by the capacitance‐voltage and saturation current methods. The composition dependence of the barrier height is φB (eV) = 0.95 − 1.90x + 0.90x2. A low barrier height with a relatively wide band gap is obtained in this system.
TL;DR: The fabrication of extremely low-loss glass optical waveguide, having as little as 4 dB/km total attenuation, has allowed interpretation of the absorption spectrum to a much greater degree than previously possible as discussed by the authors.
Abstract: The fabrication of an extremely‐low‐loss glass optical waveguide, having as little as 4 dB/km total attenuation, has allowed interpretation of the absorption spectrum to a much greater degree than previously possible It is shown that, beyond about 700 nm, intrinsic ultraviolet absorption will have no effect Between 700 and 1100 nm, all absorption can be accounted for on the basis of OH to within ±07 dB/km Marked reduction of the water content will leave the scattering as the major loss mechanism, thereby permitting total attenuations of about 2 dB/km
TL;DR: In this article, a matrix formalism for surface wave propagation in layered structures utilizing materials of arbitrary anisotropy, piezoelectricity, and conductivity is presented.
Abstract: 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.
TL;DR: In this paper, the frequencies of three lasers stabilized to molecular absorptions were measured with an infrared-frequency synthesis chain extending upwards from the cesium frequency standard, and the measured values are 29.442 483 315 (25) THz for the 10.18μm R(30) transition in CO2, 32.134 266 891 (24) THZ for the 9.33μm RCR(10) transition, and 88.376 181 627 (50) THtz for the 3.39μm P(7)-transition
Abstract: The frequencies of three lasers stabilized to molecular absorptions were measured with an infrared‐frequency synthesis chain extending upwards from the cesium frequency standard. The measured values are 29.442 483 315 (25) THz for the 10.18‐μm R(30) transition in CO2, 32.134 266 891 (24) THz for the 9.33‐μm R(10) transition in CO2, and 88.376 181 627 (50) THz for the 3.39‐μm P(7) transition in CH4. The frequency of methane, when multiplied by the measured wavelength reported in the following letter, yields 299 792 456.2(1.1) m/sec for the speed of light.
TL;DR: In this article, a transverse spatial periodic breakup of an optical beam due to self-focusing has been experimentally observed and the formation from these zones is consistent with an instability theory.
Abstract: Transverse spatial periodic breakup of an optical beam due to self‐focusing has been experimentally observed. Each focal spot evolves from a zone with well‐defined dimensions. The formation from these zones is consistent with an instability theory. Calculated and experimentally observed zone dimensions and powers are in good quantitative agreement.
TL;DR: In this paper, the authors used fused SiO2 as a new noncrystalline host for the fabrication of two types of neodymium-doped room-temperature lasers.
Abstract: Fused SiO2 has been used as a new noncrystalline host for the fabrication of two types of neodymium‐doped room‐temperature lasers, one of which operates at 1.06‐μm and the other at 1.08‐μm wavelength. The lasers have the geometry of clad optical fibers, with active cores as small as 15‐μm diameter by 1‐cm length. They are end pumped at 0.590 and 0.5145 μm with a pulsed dye laser and an argon ion laser, respectively. Thresholds as low as 1–2 mW of absorbed pump power in a 40‐μm‐diam core have been obtained, and eventual pumping with high‐radiance semiconductor optical sources appears feasible.
IBM1
TL;DR: In this paper, a class of multi-layer reflectors using a plurality of low-loss reflective elements composed of absorbing materials in the form of thin films is described wherein the differences between the absorption indices of the materials are used to obtain reflecting boundaries.
Abstract: A class of multi-layer reflectors using a plurality of low-loss reflective elements composed of absorbing materials in the form of thin films is described wherein the differences between the absorption indices of the materials are used to obtain reflecting boundaries. The class of reflector structures are designed in such a manner that when light is directed onto the structure, a standing wave is generated throughout the structure. Absorbing materials in the nodes of the standing wave do not absorb but absorbing materials in the antinodes provide enhanced absorption.
TL;DR: The principle of a new electrochromic display based on an oxidation-reduction reaction of an organic compound of the viologen family is described in this article, which is a display having a built-in memory, high contrast, a low switching voltage, and a low mean power consumption.
Abstract: The principle of a new electrochromic display based on an oxidation‐reduction reaction of an organic compound of the viologen family is described The result is a display having a built‐in memory, high contrast, a low switching voltage, and a low mean power consumption
TL;DR: In this paper, fundamental optical scattering and absorption mechanisms have been identified which limit light transmission in fiber optical waveguide materials, which are intimately associated with the random structure in the liquid and glassy state.
Abstract: 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.
TL;DR: For an optical guide with index of refraction having a small exponential variation superimposed on a constant background value, such as is found in guides made by diffusing Se into CdS, the wave equation may be solved exactly.
Abstract: For an optical guide with index of refraction having a small exponential variation superimposed on a constant background value, such as is found in guides made by diffusing Se into CdS, the wave equation may be solved exactly. The solutions and characteristic equations for determining the possible TE and TM modes are given and the properties of the modes are discussed.
TL;DR: In this paper, the third-harmonic generation in β-carotene molecules and the optical Kerr effect in β−Carotene glass were investigated. But the large values of the optical nonlinearities were attributed to the broadly delocalized Π electrons.
Abstract: Quantitative studies of third‐harmonic generation in the all‐trans β‐carotene molecule and of third‐harmonic generation and the optical Kerr effect in β‐carotene glass are reported. The large values of the optical nonlinearities are attributed to the broadly delocalized Π electrons.
TL;DR: In this article, it was shown that the W/GaAs interface of simulated diodes does not exhibit any evidence of interdiffusion or reaction, and the PtAs2/n-GaAs interfaces are associated with a slightly higher barrier height φB [inverted lazy s] 0.89 V than that found for the Pt/n•GaA interface (φB 0.6 V and increasing the ideality parameter n from 1.0 to 1.2).
Abstract: Electrical studies of W/n‐GaAs Schottky diodes have shown that aging at 350 or 500 °C does not significantly change the forward I‐V characteristics of the diodes. Using 4He+ backscattering analysis, it is shown that the W/GaAs interface of simulated diodes does not exhibit any evidence of interdiffusion or reaction. By contrast, considerable alloying occurs in both Au/GaAs and Pt/GaAs systems. In the former, Ga outdiffuses to the surface of Au and Au diffuses into GaAs upon aging at 250 or 350 °C; this has the effect of decreasing the barrier height φB from 0.9 to [inverted lazy s] 0.6 V and increasing the ideality parameter n from 1.0 to [inverted lazy s] 1.2. Interdiffusion in the Pt/GaAs couples, aged at 500 °C, results in the formation of a layered arrangement of type PtGa/PtAs2/GaAs. The PtAs2/n‐GaAs interface is associated with a slightly higher φB ([inverted lazy s] 0.89 V) than that found for the Pt/n‐GaAs interface (φB [inverted lazy s] 0.84 V).
TL;DR: In this paper, a phase matched mixture of Xe and Ar was used for third-harmonic generation from 3547 to 1182 A, where Xe is negatively dispersive, and phase matching was obtained at a ratio Xe:Ar = 1:430.
Abstract: Coherent radiation at 1182 A is obtained by third‐harmonic generation in a phase‐matched mixture of Xe and Ar. For generation from 3547 to 1182 A, Xe is negatively dispersive, and phase matching is obtained at a ratio of Xe:Ar=1:430. A conversion efficiency of 2.8% is obtained at an input power of 13 MW. As predicted by theory the conversion efficiency increases linearly to the limit of our available input power.
TL;DR: In this paper, light induced birefringence in glass optical waveguide was observed at low powers in waveguide because of the high power densities which are maintained over long lengths of guide.
Abstract: We have observed light induced birefringence in glass optical waveguide. This effect can be observed at low powers in waveguide because of the high power densities which are maintained over long lengths of guide. This effect is potentially useful as a wide‐band pulse modulator or as a device for switching or measuring the length of picosecond pulses.
TL;DR: The first practical application of smectic liquid crystals, an infrared-laser-addressed light valve for the recording, storage, and display of high-resolution graphic images, was described in this article.
Abstract: Thermally induced optical storage and erasure (local and nonlocal) of scattering centers in thin films of smectic liquid crystals has been demonstrated. These new thermo‐optic and electrothermo‐optic effects provide the basis for what is believed to be the first practical application of smectic liquid crystals, an infrared‐laser‐addressed light valve for the recording, storage, and display of high‐resolution graphic images.
TL;DR: In this paper, a cw dye laser system frequency stabilized to a high-finesse optical reference cavity is described, where the 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).
Abstract: 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.
TL;DR: In this article, a probability distribution 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.
Abstract: 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 Xp Rm 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.
TL;DR: In this article, a mechanism for the observed mechanical instability of monodomain smectic A and cholesteric liquid crystals subjected to uniaxial dilative stress is proposed.
Abstract: A mechanism is proposed for the observed mechanical instability of monodomain smectic A and cholesteric liquid crystals subjected to uniaxial dilative stress. The threshold conditions for the instability are derived, and the possible roles of dislocations in controlling the instability and in producing large plastic distortions are discussed.
TL;DR: The photoluminescent and electroluminescence properties of GaN-GaN:Mg diodes are described in this article, where the I −V characteristics showed I ∞ V3 in the region where light was emitted, and the observed power efficiency was approximately 10−5.
Abstract: The photoluminescent and electroluminescent properties of GaN–GaN:Mg diodes are described. Visible violet electroluminescence was observed with excitation voltages of 10–20 V with the emission peak in the region of 2.9 eV. The I‐V characteristics showed I ∞ V3 in the region where light was emitted, and the observed power efficiency was approximately 10−5. A photoluminescence peak at 2.9 eV provided additional evidence for an acceptor level, associated with the Mg impurity, about 0.5 eV above the valence band.