Showing papers on "Birefringence published in 1987"
TL;DR: In this paper, the physical meaning and technical implications of nonlinear pulse propagation in birefringent, single-mode fibers are discussed in detail, and the modulational instability is studied.
Abstract: Equations describing nonlinear pulse propagation in birefringent, single-mode fibers are derived. The physical meaning and technical implications of these equations are then discussed in detail. Finally, the modulational instability is studied.
482 citations
TL;DR: It is shown that while linear birefringence will lead to a substantial splitting of the two polarizations over 20 km, this effect can be eliminated by use of the Kerr nonlinearity.
Abstract: The effect of birefringence on soliton propagation in single-mode optical fibers is considered. Emphasis is on solitons with multipicosecond widths that are appropriate for communications applications. It is shown that while linear birefringence will lead to a substantial splitting of the two polarizations over 20 km, this effect can be eliminated by use of the Kerr nonlinearity. Above a certain amplitude threshold, the central frequency of each polarization shifts just enough to lock the two polarizations together.
351 citations
TL;DR: Ion implantation is a powerful technique for surface analysis and material modification and a review of the effects of ion implantation on optical properties of insulators can be found in this paper.
Abstract: Ion implantation is a powerful technique for surface analysis and material modification and this review discusses the effects that specifically relate to optical properties of insulators. By selection of ion energy and ion dose one can inject trace impurities that control luminescence, generate optical absorption bands or complex defect aggregates, stimulate production of new crystalline phases or destroy crystallinity. Implantation invariably stimulates luminescence which provides a sensitive means of analysis to measure purity and near-surface defect concentrations. Post-implantation measurements reveal changes in many physical and chemical properties of the materials. Some, such as chemical reactivity, can increase a thousandfold, others such as birefringence, electro-optic and acoustic wave parameters are reduced. One major property which can be controlled is the refractive index; thus optical waveguides, and ultimately, complex integrated optical devices can be precisely defined by ion implantation.
255 citations
Patent•
17 Feb 1987TL;DR: In this article, an electrically controlled birefringence effect and processes for the production of the cell and a uniaxial medium or material of negative optical anistropy usable therein are described.
Abstract: Liquid crystal cell using the electrically controlled birefringence effect and processes for the production of the cell and a uniaxial medium or material of negative optical anistropy usable therein. The cell can comprise two crossed rectilinear polarizers, two glass plates provided with transparent electrodes and placed between said polarizers, a liquid crystal layer between the plates and, between a plate and a polarizer, a layer of a negative uniaxial thermoplastic polymer having its extraordinary axis perpendicular to the plates. This layer can be obtained by heating the polymer up to the isotropic state, under a uniform presure on the polarizers, cooling and eliminating the pressure. Application to the production of data display devices.
160 citations
TL;DR: In this paper, a nonlinear optical crystal with point group symmetry mm2 has been grown by a temperature difference solution growth technique, and its linear and non-linear optical properties have been investigated.
Abstract: A new nonlinear optical crystal 2‐cyclooctylamino‐5‐nitropyridine (COANP) with point group symmetry mm2 has been grown by a temperature difference solution growth technique. Its linear and nonlinear optical properties have been investigated. The refractive indices na =1.702, nb =1.847, and nc =1.681 (λ=550 nm) and the nonlinear optical susceptibilities d31 and d33 (λω =1.06 μm) have been determined. Type I phase matching for Nd:YAG lasers (λ=1.06 μm) has been demonstrated for the configuration using a combination of d31 and d32 by angle tuning. A peak efficiency η=P2ω/Pω =3.6% has been observed with a 0.90‐mm‐thick crystal and a fundamental power Pω =560 W.
126 citations
TL;DR: The intrinsic fiber absorbance, defined operationally as log10 of the ratio of incident light to transmitted light intensity, was similar in intact and cut preparations, as were the changes that accompanied stimulation; changes are probably due to a progressive alteration in the internal state of the cut fibers.
Abstract: �This article describes a new apparatus for making simultaneous optical measurements on single muscle fibers at three different wavelengths and two planes of linear polarization There are two modes of operation : mode 1 measures the individual absorbances of light linearly polarized along and perpendicular to the fiber axis, and mode 2 measures retardation (or birefringence) and the average of the two absorbance components Although some intact frog twitch fibers were studied, most experiments used cut fibers (Hille, B , and D T Campbell 1976 Journa l of General Physiology 67:265-293) mounted in a double-Vaseline-gap chamber (Kovacs, L , E Rios, and M F
90 citations
TL;DR: Measurements of the frequency dependence of the state of polarization at the end of a low-birefringence long-cabled (50-km) optical fiber using the Poincaré sphere representation find the principal states of polarization and their group-delay difference.
Abstract: We report some results of measurements of the frequency dependence of the state of polarization at the end of a low-birefringence long-cabled (50-km) optical fiber. The principal states of polarization and their group-delay difference were determined by making use of the Poincare sphere representation.
88 citations
TL;DR: In this paper, the authors reviewed the properties and electro-optic effects of nematic liquid crystals and discussed the advantages and disadvantages of three device configurations (parallel, twisted, and perpendicular alignment) for long-wavelength applications.
Abstract: Infrared properties and electro-optic effects of nematic liquid crystals are reviewed. Physical origins and characterization techniques of infrared birefringence and rotatory power are described. Advantages and disadvantages of three device configurations--parallel, twisted, and perpendicular alignments--are analyzed. Among them, parallel alignment shows the best potential for long-wavelength applications. Several methods for improving the response times of nematic liquid crystals with emphasis in the infrared region are briefly discussed.
87 citations
TL;DR: In this article, an ultrafast time-domain optical multi/demultiplexer utilizing the optical Kerr effect in two birefringent fibres concatenated with each fast axis crossed is proposed.
Abstract: An ultrafast time-domain optical multi/demultiplexer utilising the optical Kerr effect in two birefringent fibres concatenated with each fast axis crossed is proposed. Stable demultiplexing of an ultrashort 30 ps optical pulse train at 1.97 GHz from a gain-switched DFB LD has been successfully demonstrated using CW mode-locked Nd:YAG laser control pulses.
71 citations
Patent•
13 May 1987TL;DR: In this article, the position, shape and material of the elongated member or the groove are determined in such a way that stress-induced birefringence produced in the core portion in accordance with a difference in thermal expansion coefficient between the substrate and the single mode optical waveguide is a desired value.
Abstract: In a single mode optical waveguide having a substrate, a cladding layer formed on the substrate, a core portion embedded in the cladding layer, and an elongated member for applying a stress to the core portion or a stress relief groove for relieving a stress from the core portion in the cladding layer along the core portion. The position, shape and material of the elongated member or the groove are determined in such a way that stress-induced birefringence produced in the core portion in accordance with a difference in thermal expansion coefficient between the substrate and the single mode optical waveguide is a desired value.
70 citations
TL;DR: In this article, a tunable optical transmission filter for 1.5?n with a bandwidth of 12 A and a tuning range of at least 80 A was proposed based on wavelength-dependent polarisation conversion in a birefringent waveguide.
Abstract: We report a tunable optical transmission filter for 1.5?n with a bandwidth of 12 A and a tuning range of at least 80 A. The filter is based on wavelength-dependent polarisation conversion in a birefringent waveguide and employs a periodic electrode structure with interleaved birefringence tuning electrodes.
TL;DR: In this article, birefringent filter synthesis techniques are demonstrated to achieve very flat channel passbands for wavelength division multiplexers (WDM) with typical optical crosstalk values of?19 dB.
Abstract: Birefringent filter synthesis techniques are demonstrated to achieve very flat channel passbands for wavelength-division multiplexers. The crystal thickness and birefringence can be used to scale a given design to very small channel separations, limited primarily by the spectra of the lasers and their drift. Experimental results are reported, with typical optical crosstalk values of ?19 dB.
Patent•
17 Feb 1987
TL;DR: In this article, a double liquid crystal layer with a double cross rectilinear polarizer was used to produce a negative optical anisotropy uniaxial material usable in a television screen.
Abstract: Cell with a double liquid crystal layer using the electrically controlled birefringence effect and process for producing a negative optical anisotropy uniaxial material usable in said cell. The cell can comprise two crossed rectilinear polarizers, three glass plates provided with transparent electrodes and placed between said polarizers, two liquid crystal layers between the plates and, between a plate and a polarizer, a sheet of the medium, whose extraordinary axis is perpendicular to the plates. This sheet can be obtained by heating a thermoplastic polymer up to the isotropic state, under a uniform pressure on the polarizers, cooling and eliminating the pressure. The cell is designed in such a way that the molecules of the respective layers tilt in two directions forming the same angle with the homeotropy direction, when an exciting voltage is applied between the electrodes, said directions, viewed in projection on a plate, also being opposite in the main observation plane. Application to the production of television screens.
TL;DR: In this paper, the polarization properties of volume phase gratings induced in photorefractive materials that are both optically active and linearly birefringent, such as Bi12SiO20, Bi12GeO20 and Bi12TiO20 have been studied under the assumption of a nondepleted readout beam.
Abstract: We study the polarization properties of volume phase gratings induced in photorefractive materials that are both optically active and linearly birefringent, such as Bi12SiO20, Bi12GeO20, and Bi12TiO20. Analytic expressions for the diffraction efficiency and for the orientation and the ellipticity of the diffracted light have been derived for the 〈110〉 and 〈001〉 configurations under the assumption of a nondepleted readout beam. The physical parameters that determine the polarization characteristics of the diffracted light are the orientation of the readout vector, the crystal thickness, the optical activity, and the electric-field-induced linear birefringence. Our results are valid for arbitrary values of these parameters. The particular cases of zero optical activity, zero linear birefringence, a thin crystal, or a specific readout-vector orientation can be deduced from the general formulas. The analytic expressions that we have derived permit an optimal choice of different parameters for the image-processing and beam-coupling applications of these materials.
TL;DR: In this article, the degree of molecular orientation in oriented polymers was characterized by measuring birefringence, and specimens prepared for measurements of tensile yield stress and shrinkage stress at elevated temperature.
TL;DR: A new method for simultaneous measurement of the three refractive indices, based on laser-beam splitting due to bireflectance, is demonstrated in the biaxial CdWO4 crystal.
Abstract: The bireflectance effect is observed when a light beam is internally reflected in an anisotropic material. Generally, an unpolarized light beam splits into four beams on reflection. A new method for simultaneous measurement of the three refractive indices, based on laser-beam splitting due to bireflectance, is demonstrated in the biaxial CdWO4 crystal. The three principal refractive indices of CdWO4 were obtained in the visible range. At λ = 633 nm, nX = 2.09 ± 0.01, nY − nX = 0.052 ± 0.001, and nZ − nX = 0.114 ± 0.002.
TL;DR: In this article, the hydrodynamic diameter of particles deduced from experiments is compared to a numerical computation with a log-normal distribution for a narrow distribution (σ ≃ 0.25).
Abstract: Relaxation time measurements of magnetically induced birefringence of ferrofluid solutions are performed with samples of various polydispersities. d H, the hydrodynamic diameter of particles deduced from experiments, is compared to a numerical computation with a log-normal distribution. Dynamic magnetic birefringence appears to be a good test of the tail of the sample size distribution. For a narrow distribution (σ ≃ 0.25), the experiment is in good agreement with the model: dH is two times larger than the most probable diameter and corresponds to the largest particles in the sample.
TL;DR: In this paper, the index change and birefringence resulting from K+-Na+ ion exchange in glass are mainly due to induced surface stresses, and the importance of this fact with regard to the fabrication of optical waveguides is discussed.
Abstract: The index change and birefringence resulting from K+-Na+ ion exchange in glass are shown to be mainly due to induced surface stresses. The importance of this fact with regard to the fabrication of optical waveguides is discussed.
TL;DR: A Jones matrix approach is used to study a magnetooptic read-back system which uses a wave plate for maximizing the signal and minimizing the noise.
Abstract: A Jones matrix approach is used to study a magnetooptic read-back system which uses a wave plate for maximizing the signal. The effects and interactions of Kerr rotation, Kerr ellipticity, birefringence in the substrate and in the optical system, and misalignment of the optical components are considered. Several criteria are developed for maximizing the signal and minimizing the noise.
TL;DR: In this article, a technique for fabricating helical-core circularly birefringent fibres is reported. Extremely high levels of circular bireFringence are achieved (B = 2.1 × 10-4 at 633 nm).
Abstract: A technique for fabricating helical-core circularly birefringent fibres is reported. Extremely high levels of circular birefringence are achieved (B = 2.1 × 10-4 at 633 nm). Because of its unique structure, this fibre remains single-mode up to V values of 25.
TL;DR: The use of optical rotators and waveplates to compensate for thermally induced birefringence in cylindrical laser rods is reported, which allows polarization coupled lasers to operate efficiently at high average power levels.
Abstract: The use of optical rotators and waveplates to compensate for thermally induced birefringence in cylindrical laser rods is reported. The use of these components allows polarization coupled lasers to operate efficiently at high average power levels. Experimentally a Nd:YAG oscillator has been operated in a Q-switched TEM(00) mode giving 300-mJ pulses and 15 W of average power.
TL;DR: The potential use of self-induced birefringence effects in a periodically modulated nonlinear medium for relatively low-power intensity discrimination, all-optical polarization switching, and small-signal amplification using linearly polarized beams is described.
Abstract: Self-induced birefringence effects in a periodically modulated nonlinear medium are investigated An input beam linearly polarized along the axis of a fiber polarization-rocking filter undergoes a spatial instability as the input power crosses a threshold value that scales linearly with the coupling strength We describe the potential use of this effect for relatively low-power intensity discrimination, all-optical polarization switching, and small-signal amplification using linearly polarized beams The wavelength for maximum polarization conversion between the axes can be tuned by varying the input power, and the filter bandwidth narrows with increasing power
TL;DR: The output signal of a birefringent fiber gyroscope is analyzed, and sources of error due to polarization cross coupling in the fiber and fiber components are identified.
Abstract: The output signal of a birefringent fiber gyroscope is analyzed, and sources of error due to polarization cross coupling in the fiber and fiber components are identified. Techniques to suppress such errors by modulating the fiber birefringence and balancing the optical power in the two polarization modes are proposed and demonstrated.
TL;DR: A quasi-optical technique, namely, dispersive Fourier transform spectrometry, has now been improved to provide high-precision continuous data of complex refractive index, complex dielectric permittivity, and loss tangent of materials at millimeter wavelengths as discussed by the authors.
Abstract: A quasi-optical technique, namely, dispersive Fourier transform spectrometry, has now been improved to provide high-precision continuous data of complex refractive index, complex dielectric permittivity, and loss tangent of materials at millimeter wavelengths. The use of a polarizing two-beam interferameter is ideally suited for the measurement of birefringent materials. A massive birefringent effect (δ∊′ 2.193) is now observed for crystalline sapphire (Al 2 O 3 ). The bifringent effect for crystalline quartz is much smaller (δ∊′ ⋍ 0.2). New millimeter-wave results of commercially available ceramic alumina (Al 2 O 3 ) are compared with those of crystalline sapphire.
TL;DR: The linear birefringence of magneto-optic garnet thin films can be reduced to small values by growing multilayer films to minimize the shape effect, annealing at high temperatures to reduce the growth-induced effect, and growing the films in compression to control the photoelastic effect as discussed by the authors.
Abstract: The linear birefringence of magneto‐optic garnet thin films, which interferes with the Faraday rotation in waveguide devices, can be reduced to small values by growing multilayer films to minimize the shape effect, annealing at high temperatures to reduce the growth‐induced effect, and growing the films in compression to control the photoelastic effect. The remaining birefringence can be reduced to zero by chemically etching the film until the effects exactly cancel each other at a particular wavelength. This etch‐tuning procedure is demonstrated on a two‐layer bismuth‐yttrium iron garnet (Bi‐YIG) film at wavelengths of 1.51 and 1.32 μm. Extinction ratios of 100 to 1 have been achieved at 45° and 90° Faraday rotations at both wavelengths.
TL;DR: In this article, the effect of the chiral molecules appears in the effective elastic constant, ke, which will decrease and then increase with respect to the increasing of the concentration of the Chiral molecules.
Abstract: The ferronemtaic state which was described theoretically by Brochard and de Gennes can be achieved by doping the liquid crystal with anisotropic ferromagnetic particles. The homeotropic liquid crystal film was successfully prepared for the ferronematic liquid crystal doped with low concentration chiral molecules. The magnetic-field-induced-birefringence due to molecular reorientation was treated both theoretically and experimentally. In the low field regime (<2.5G), it is theoretically predicted that the induced phase difference between the ordinary and extraordinary ray of a normally incident probe beam is proportional to the square of the external magnetic field and to the fifth power of the thickness of the sample film. This is verified by the experimental results. The effect of the chiral molecules appears in the effective elastic constant, ke , which will decrease and then increase with respect to the increasing of the concentration of the chiral molecules.
TL;DR: Self-induced stochastic behavior for the evolution of light along a periodically perturbed two-mode nonlinear optical waveguide is predicted and implications for recently demonstrated all-optical switching using birefringent fibers are discussed.
Abstract: Self-induced stochastic behavior for the evolution of light along a periodically perturbed two-mode nonlinear optical waveguide is predicted. Implications for recently demonstrated all-optical switching using birefringent fibers are discussed.
Patent•
27 Feb 1987
TL;DR: In this paper, a two-position optical deflector device is used to increase the resolution of a liquid-crystal imager, which is used downstream of an actual LCR imager with row-and-column crossed electrodes sandwiched between a polariser and an analyser.
Abstract: The device makes it possible to increase resolution. It is used downstream of the actual liquid-crystal imager 1 consisting of a cell 2 with row-and-column crossed electrodes sandwiched between a polariser 3 and an analyser 4. This imager is followed by a two-position optical deflector device 5 which may consist of a liquid-crystal polarisation inverter (reverser) 6 and a birefringent medium 7 of the Wollaston compensator type having two birefringent prisms. The invention may be applied to high-resolution avionics displays.
TL;DR: In this paper, an analytic expression for the optical field propagating normally in a general twisted nematic liquid-crystal structure was obtained for the first time, based upon which the optical transmissions of the general twisted nematic liquidcrystal displays (including standard twisted, super twisted, supertwisted birefringence effect, lower twisted, and optical mode interference) with arbitrary polarizer orientations, liquid crystal indices of refraction, twist angle, surface pretilt angle, and cell thickness were discussed.
Abstract: An analytic expression for the optical field propagating normally in a general twisted nematic liquid‐crystal structure is obtained for the first time. Based upon this, analytic expressions are obtained for the optical transmissions of the general twisted nematic liquid‐crystal displays (including standard twisted nematic, supertwisted, supertwisted birefringence effect, lower twisted, and optical mode interference) with arbitrary polarizer orientations, liquid‐crystal indices of refraction, twist angle, surface pretilt angle, and cell thickness. Routes for improving the display performances are discussed.
TL;DR: In this article, coupled wave equations were combined with a linearized model of the photorefractive recording process (single trap level, single mobile charge species) to analyze the impact of self-diffraction effects on the polarization state evolution.
Abstract: Doppler-enhanced self-diffraction in two-beam coupling experiments with sillenite crystals exhibits pronounced optical polarization effects due to the concomitant presence of natural optical activity and electric-field-induced linear birefringence. Coupled wave equations that describe the polarization properties, exclusive of self-diffraction effects, have previously been derived for the two principal crystal orientations most commonly used in photorefractive recording. In this paper, the coupled wave equations are combined with a linearized model of the photorefractive recording process (single trap level, single mobile charge species) to analyze the impact of self-diffraction effects on the polarization state evolution. Numerical solutions of these equations yield optimum configurations for enhanced gain and improved image contrast in two-wave mixing with such materials. In addition, inclusion of optical activity in the model emphasizes the contribution of this effect to the apparent reduction of the effective electrooptic coefficient of bismuth silicon oxide crystals.