Showing papers in "Applied Physics Letters in 1967"
TL;DR: In high precision holographic imagery of weak objects of small angular subtense, electronic detection and digital image formation have distinct advantages as mentioned in this paper, and experiments with a vidicon detector and a PDP-6 computer have yielded reconstructed images of good quality with computation times of five minutes.
Abstract: In high precision holographic imagery of weak objects of small angular subtense, electronic detection and digital image formation have distinct advantages. Experiments with a vidicon detector and a PDP‐6 computer have yielded reconstructed images of good quality with computation times of five minutes.
1,002 citations
TL;DR: The fluorescence of Y3Al5O12−Ce3+ under cathode-ray excitation consists of an emission band peaking at 550 nm, and the decay time is 0.07-0.08 μsec as mentioned in this paper.
Abstract: The fluorescence of Y3Al5O12–Ce3+ under cathode‐ray excitation consists of an emission band peaking at 550 nm. The decay time is 0.07–0.08 μsec. In view of these properties this phosphor is very suitable for flying‐spot cathoderay tubes for color television.
461 citations
TL;DR: In this article, standing wave excitation of two-photon fluorescence in solutions or organic molecules was reported, allowing the direct display and measurement of optical pulses as short as 1−2 × 10−2 sec.
Abstract: Standing wave excitation of two‐photon fluorescence in solutions or organic molecules is reported. The observations allow the direct display and measurement of optical pulses as short as 1−2 × 10−2 sec.
392 citations
TL;DR: In this paper, the authors demonstrated efficient spectral narrowing and tunability over a wide spectral range, using diffraction gratings as cavity reflectors in solid and liquid organic dye lasers.
Abstract: Efficient spectral narrowing, and tunability over a wide spectral range, has been demonstrated in solid and liquid organic dye lasers using diffraction gratings as cavity reflectors.
363 citations
TL;DR: In this article, the shape of the fast pulses from a mode-locked Ndglass laser was measured at half power of between 4 and 6 picoseconds, and the technique was capable of measuring pulse widths at least as short as 4 × 10−13 sec.
Abstract: The special symmetry properties of second‐harmonic generation at the surface of a GaAs crystal are used in a technique which measures the shape of the fast pulses from a mode‐locked Nd‐glass laser The pulses studied were found to have a full width at half power of between 4 and 6 picoseconds The technique is capable of measuring pulse widths at least as short as 4 × 10−13 sec
276 citations
TL;DR: In this article, the system of ferroelectric strontium barium niobates, SrxBa1•xNb2O6, was investigated and linear electrooptic coefficients as large as r ∼ 4 × 10−5 cm/statvolt have been measured.
Abstract: Linear electro‐optic coefficients as large as r ∼ 4 × 10‐5 cm/statvolt have been measured in the system of ferroelectric strontium barium niobates, SrxBa1‐xNb2O6. In the first crystals x varies from 0.75 to 0.25, with Curie temperatures ranging from ∼60°C to 250°C. At 15 Mc, the respective half‐wave field distance products range from 48 to 1236 V.
253 citations
TL;DR: In this article, a method for enhancing the sensitivity of thin films of certain oxides to small amounts of airborne hydrogen and other reducing gases is described, and the quantitative behavior of thin film of platinum-activated tungsten oxide is illustrated.
Abstract: A method is described for enhancing the sensitivity of the thin films of certain oxides to small amounts of airborne hydrogen and other reducing gases. The quantitative behavior of thin films of platinum‐activated tungsten oxide is illustrated.
221 citations
TL;DR: The useful nonlinear coefficients of Ba2NaNb5O15 are approximately twice those of LiNbO3 as mentioned in this paper, which is a filled (A sites) structure composition and at room temperature does not have the serious problem of optically induced refractive index inhomogeneities (''optical damage'').
Abstract: The useful nonlinear coefficients of Ba2NaNb5O15 are approximately twice those of LiNbO3. This material is a filled (A sites) structure composition and at room temperature does not have the serious problem of optically induced refractive index inhomogeneities (``optical damage''). Also, the material has unique and reproducible phasematch temperatures. The electro‐optic half‐wave voltage of this material in the optimum direction is 1570 V.
201 citations
TL;DR: In this article, the electron velocity field characteristic of insulating GaAs has been measured by injecting electrons with an electron beam and the measured low field mobility is 7500 cm2/V•sec with an initial negative differential mobility of −2400 cm 2/V •sec at a threshold field of 3.2 kV/cm.
Abstract: The electron velocity‐field characteristic of insulating GaAs has been measured by injecting electrons with an electron beam. The measured low field mobility is 7500 cm2/V‐sec with an initial negative differential mobility of −2400 cm2/V‐sec at a threshold field of 3.2 kV/cm.
184 citations
TL;DR: In this paper, the ejection of electrons from inner shells of atoms through photoionization is suggested as a straightforward means of creating population inversions at vacuum uv and x-ray wavelengths.
Abstract: The ejection of electrons from inner shells of atoms through photoionization is suggested as a straightforward means of creating population inversions at vacuum uv and x‐ray wavelengths. This can be accomplished by photon sources covering broad bands. Sodium vapor and solid copper are examined as possible candidates for laser action at 372 A and 1.54 A, respectively. A first‐rise traveling wave pump must be used; pumping powers required for superradiant operation run into several gigawatts, with rise times ranging from 10−9 sec in the near‐vacuum uv to 10−15 sec in the x‐ray region.
179 citations
TL;DR: The NaCl structures PbS, PbSe, pbTe and SnTe have been found to transform to a Pnma orthorhombic (distorted NaCl) structure under high pressures as discussed by the authors.
Abstract: The NaCl structures PbS, PbSe, PbTe and SnTe have been found to transform to a Pnma orthorhombic (distorted NaCl) structure under high pressures. Epitaxial growth on rock salt of thin films of normally orthorhombic (Pnma) SnS, SnSe and PbSnS2 induces NaCl structures. There exists a close correlation between the lattice constants of the corresponding NaCl and the orthorhombic polymorphic structures of the Pb and Sn compounds.
TL;DR: In this article, a technique for observing high pressure shock waves generated in water by Q-switched lasers is described, using the laser as an illuminating source for a shadowgraph system and as a tool for generating the shocks.
Abstract: High‐pressure shock waves have been generated in water by Q‐switched lasers. A technique for observing the shocks using the laser as an illuminating source for a shadowgraph system and as a tool for generating the shocks is described.
TL;DR: In this paper, a flat-plate Blumlein pulse generator was used to produce a 2.5MW pulse with nitrogen and a 1.5 MW pulse with neon. But the power output in the direction of the wave of excitation was at least ten times that in the other direction.
Abstract: Experiments are described in which nitrogen and neon lasers are excited by a wave of current excitation which effectively travels from one end of the laser to the other with its velocity matching that of the stimulated emission. This type of excitation is accomplished with a low‐impedance flat‐plate Blumlein pulse generator. The power output in the direction of the wave of excitation is at least ten times that in the other direction. A 2.5‐MW pulse of about 4‐nsec duration is obtained with nitrogen and a 190‐kW pulse of about 1.5 nsec with neon.
TL;DR: In this article, the Hermite-Gaussian symmetry in the junction plane has been observed in both p+nn+ and p+n+ GaAs specially constructed with a stripe geometry contact.
Abstract: Far‐field radiation patterns with Hermite‐Gaussian symmetry in the junction plane have been observed in both p+nn+ and p+n+ GaAs lasers specially constructed with a stripe geometry contact. The Hermite‐Gaussian symmetry implies the presence of a lens‐like medium between the cleavage plane mirrors. Compared with conventional junction lasers, improved mode control is obtained.
TL;DR: In this paper, an excited 20Ne at 0.1 torr was placed inside the cavity of a single-frequency, 6328-A laser and a peak appeared in the output power caused by an inverted Lamb dip effect.
Abstract: Excited 20Ne at 0.1 torr was placed inside the cavity of a single‐frequency, 6328‐A laser. A pronounced peak appeared in the output power, caused by an inverted Lamb dip effect. Because of the low pressure used, this peak was only 30 ± 5 MHz wide and must be very near the atomic resonant frequency. In contrast, the overall output curve was blue‐shifted 60 ± 10 MHz by the 3 torr nominal pressure in the laser gain tube. This saturated absorption effect can be used as an absolute reference for the frequency stabilization of He–Ne and similar lasers.
TL;DR: In this article, an efficient visible light emitting diodes have been fabricated from Ga1•xAlxAs, which had their emission at 1.70 eV and switching time for the light emission at 300°K was measured to be 60 nsec.
Abstract: Efficient visible light emitting diodes have been fabricated from Ga1‐xAlxAs. Epitaxial layers were obtained by a modified solution growth technique. External quantum efficiencies of up to 3.3% have been measured at room temperature on diodes, which had their emission at 1.70 eV. The switching time for the light emission at 300°K was measured to be 60 nsec.
TL;DR: In this article, the absolute frequencies of the 311μ and the 337μ transitions of the CN gas laser were measured to within a few parts in 107.5 GHz by mixing the laser frequencies with high order harmonics of a microwave signal in a silicon diode.
Abstract: Absolute frequencies of the 311‐μ and the 337‐μ transitions of the CN gas laser are measured to within a few parts in 107. This is achieved by mixing the laser frequencies with high order harmonics of a microwave signal in a silicon diode. The beat frequencies of these two transitions which falls at 73.5 GHz is also measured directly. The Zeeman effect of these two laser transitions is studied. Based on a detailed analysis, it is found that the existing identification of these transitions is inconsistent with our observations.
TL;DR: In this article, optical and electrical measurements on thin sections of Bi4Ti3O12 in orientations not previously measured have yielded the following results: the symmetry is monoclinic, point group m is greater than 30 μC/cm2 and lies in a direction tilted slightly from the major crystal surface.
Abstract: Optical and electrical measurements on thin sections of Bi4Ti3O12 in orientations not previously measured have yielded the following results. The symmetry is monoclinic, point group m. The spontaneous polarization Ps is greater than 30 μC/cm2 and lies in a direction tilted slightly from the major crystal surface. Switching, with fields perpendicular to the major crystal surface, occurs by a small ``rocking'' of this large Ps vector. The large component parallel to the major crystal surface can also be switched with high fields. Thus, there are four possible spontaneous polarization directions in the virgin crystal giving rise to complex domain structures.
TL;DR: Proustite (Ag3AsS3) as mentioned in this paper is a new acentric crystal for optical mixing, synthesized as large transparent single crystals with point group symmetry 3m.
Abstract: Proustite (Ag3AsS3), a new acentric crystal for optical mixing, has been synthesized as large transparent single crystals. It is uniaxial, having point group symmetry 3m. Proustite transmits from 0.6 to 13 μm, and has a large negative birefringence (n0 − nE ∼ 0.2). Using second‐harmonic generation from a 1.152‐μm laser, we estimate the nonlinear coefficients to be |d22P|=50|d36KDP| and |d31P|=30|d36KDP|. New optical mixing possibilities arise from the exceptionally wide range of processes that can be phase‐matched and the large nonlinear coefficients.
TL;DR: The nonlinear coefficient d31 of K.6Li.4NbO3 was shown to be equal to d31 in this paper, which is the same as the nonlinear coefficients of Li.
Abstract: The nonlinear coefficient d31 of K.6Li.4NbO3 is equal to d31 of LiNbO3. Also, the serious problem of optically induced refractive‐index inhomogeneities which has been observed in many nonlinear materials, notably LiNbO3, is not observed in this new material. The electro‐optic half‐wave voltage of this new material is 930 V.
TL;DR: In this article, a self-induced negative lens is formed when molecular liquids are inserted in the path of a CW laser beam, which allows for its application as a power controller.
Abstract: Due to residual absorption, a self‐induced negative lens is formed when molecular liquids are inserted in the path of a CW laser beam. This lens has a power‐dependent focal length which allows for its application as a power controller. Experimental results show that control under 3% is obtained for a CW argon laser.
TL;DR: In this paper, the temperature dependence and absolute sign of the electrooptic coefficients in single-crystal LiNbO3 were measured in the temperature range of 20°−250°C using a vibrating-mirror Michelson interferometer.
Abstract: The temperature dependence and the absolute sign of the electro‐optic coefficients in single‐crystal LiNbO3 were measured in the temperature range of 20°‐250°C using a vibrating‐mirror Michelson interferometer. The linear electro‐optic effect in LiNbO3 is related through a simple model to the quadratic electro‐optic effect in paraelectric perovskites. The measured magnitude, sign, and the temperature dependence of the electro‐optic effect in this crystal are consistent with this model.
TL;DR: In this paper, an approximate zero-temperature upper critical field limit of Hc20 (max) consistent with the recent extreme type-II theory of Werthamer, Helfand, and Hohenberg (WHH) was deduced by assuming an electron mean free path l 0 comparable to the interatomic spacing, with approximate applicability of the WHH theory in this domain, and Tc and l independent parameters typical of present-day high-field superconductors.
Abstract: Approximate zero‐temperature upper‐critical‐field limits Hc20 (max), consistent with the recent extreme‐type‐II theory of Werthamer, Helfand, and Hohenberg (WHH), are deduced by assuming (1) an electron mean free path l0 comparable to the interatomic spacing, (2) a spin‐orbit‐coupling‐induced spin‐flip mean free path lso=2l0, with approximate applicability of the WHH theory in this domain, and (3) Tc and l‐independent parameters typical of present‐day high‐field superconductors. Highest Hc20(max) ≈ 850 kG are obtained for high‐Tc β‐tungsten‐structure compounds.
TL;DR: The broad time constant dispersion of states at the SiSiO2 interface can be explained by the tunneling model introduced by F. P. Heiman and G. Warfield as mentioned in this paper.
Abstract: The broad time constant dispersion of states at the Si‐SiO2 interface can be explained by the tunneling model introduced by F. P. Heiman and G. Warfield.1 The spectrum of time constants is caused by the exponential decay of the effective capture cross section for larger tunneling distances. A good agreement between theory and experiments was obtained for the oxide traps concentrated within about 10 A from the interface.
TL;DR: In this paper, the nonresonant third order nonlinear dielectric susceptibility coefficients of several gases were measured in a four wave mixing experiment and used to calculate the amount of third harmonic radiation generated in gases in a focused laser beam.
Abstract: The nonresonant third order nonlinear dielectric susceptibility coefficients of several gases were measured in a four wave mixing experiment. These coefficients were used to calculate the amount of third harmonic radiation generated in gases in a focused laser beam. No signal distinguishable from noise was ever seen from gases, although more than 104 times the minimum detectable signal was predicted.
TL;DR: In this paper, the shape of the edge in such materials is not dependent on phonon interactions, and is attributable to the state of charge of impurities in the material, and not to phonon interaction.
Abstract: Comparative measurements of the absorption edge of p‐type GaAs and compensated GaAs over a wide temperature range demonstrate that the shape of the edge in such materials is not dependent on phonon interactions, and is attributable to the state of charge of impurities in the material.
TL;DR: In this article, a physical model of the electro-optic effect is presented which is based on an extension of Bloembergen's anharmonic oscillator model for nonlinear optical processes.
Abstract: A physical model of the electro‐optic effect is presented which is based on an extension of Bloembergen's anharmonic oscillator model for nonlinear optical processes. Expressions for the electro‐optic coefficients of centrosymmetric and noncentrosymmetric crystals are derived and shown to be in good agreement with experiment. Miller's empirical relation between the linear and nonlinear susceptibilities is also explained for the electro‐optic case.
TL;DR: In this paper, the authors observed a pattern of concentric annuli formed as a result of thermal effects upon a light beam, which is the first time such patterns have been reported.
Abstract: In this Letter we discuss the observation of a pattern of concentric annuli formed as a result of thermal effects upon a light beam To our knowledge, this is the first time such patterns have been reportedWhen a beam of light passes through an absorbing medium whose refractive index decreases as a function of temperature, the medium behaves as a negative lens Gordon et al1 observed this phenomenon by placing a cell containing an absorbing liquid between the mirrors of a helium‐neon laser The absorption constants for several liquids with very low absorbencies have been determined using this effect2 Rieckhoff3 measured the increase in the diameter of a light beam that passed through a thermal self‐defocusing liquid placed external to the laser inter‐ferometer Recently Leite et al4 demonstrated that this effect may be used as a power limiting device
TL;DR: In this paper, the Hall mobility and conduction electron concentration n of semiconducting, spraydeposited CdS thin films are both reduced by chemisorbed oxygen, the former by a larger factor than the latter.
Abstract: The Hall mobility μ and conduction electron concentration n of semiconducting, spray‐deposited CdS thin films are both reduced by chemisorbed oxygen, the former by a larger factor than the latter. The temperature dependence of n is not affected by chemisorption whereas that of μ is changed from practically no dependence on temperature to a thermally activated dependence. This change is attributed to additional scattering introduced by the chemisorbed ions.
TL;DR: In this article, the interaction between waves in an idealized saturable absorber is discussed and it is shown that the presence of a strong wave will cause the line to appear to be "hole-burned" when probed by a second wave, even though the broadening mechanisms are conventionally homogeneous.
Abstract: The interaction between waves in an idealized saturable absorber is discussed. It is shown that the presence of a strong wave will cause the line to appear to be ``hole‐burned'' when probed by a second wave, even though the broadening mechanisms are conventionally homogeneous. This effect would be expected to work against the tendency of dye‐switched ruby lasers to operate in a single mode. Related effects should play a role in optical pulse generators and in other devices using saturable absorbers.