Showing papers on "Optical polarization published in 1993"
TL;DR: This work demonstrates the polarization dependence of the nonlinear refractive index or two-photon absorption coefficient in BaF2, KTP, and GaAs at wavelengths of 532 and 1064 nm by incorporating a wave plate into the Z-scan apparatus.
Abstract: We introduce a method for measuring the anisotropy of nonlinear absorption and nonlinear refraction in crystals by incorporating a wave plate into the Z-scan apparatus. We demonstrate this method by measuring the polarization dependence of the nonlinear refractive index or two-photon absorption coefficient in BaF2, KTP, and GaAs at wavelengths of 532 and 1064 nm.
169 citations
TL;DR: In this paper, the authors prove three optical reversibility theorems that relate the polarization ellipticity at the output of an optical system to the polarization of the retroreflected light at the input.
Abstract: Using Jones’s formalism, we prove three optical reversibility theorems that relate the polarization ellipticity at the output of an optical system to the polarization of the retroreflected light at the input. We describe how these theorems can be used to measure the ellipticity of a polarization remotely and thus to control it remotely. As an example, we use this method to create a linear or a circular polarization after a total internal reflection inside a prism, and the impurity of polarization is found to be better than 10−3. Finally we describe the use of this remote control to create polarization configurations that are useful for laser cooling of atoms.
136 citations
15 Jun 1993
TL;DR: An algorithm for separating the specular and diffuse components of reflection from images is presented and can handle highlights that have a varying diffuse component, as well as highlights that include regions with different reflectance and material properties.
Abstract: An algorithm for separating the specular and diffuse components of reflection from images is presented. The method uses color and polarization simultaneously to obtain strong constraints on the reflection components at each image point. Polarization is used to locally determine the color of the specular component, constraining the diffuse color at a pixel to a one-dimensional linear subspace. This subspace is used to find neighboring pixels whose color is consistent with the pixel. Diffuse color information from consistent neighbors is used to determine the diffuse color of the pixel. In contrast to previous separation algorithms, the proposed method can handle highlights that have a varying diffuse component, as well as highlights that include regions with different reflectance and material properties. Experimental results obtained by applying the algorithm to complex scenes with textured objects and strong interreflections are presented. >
129 citations
TL;DR: In this paper, it was shown that the dielectric function ∊o of the outermost region is determinable exactly and analytically at any given wavelength from the value and the thickness derivative of the complex reflectances for p-polarized, s- polarized or normally incident light without any knowledge of the underlying structure.
Abstract: For stratified samples where material is being uniformly deposited or removed at a known rate, I show that the dielectric function ∊o of the outermost region is determinable exactly and analytically at any given wavelength from the value and the thickness derivative of the complex reflectances for p-polarized, s-polarized, or normally incident light without any knowledge of the underlying structure. This minimal-data approach greatly simplifies analysis compared with the standard procedure, in which dielectric functions are determined sequentially from a combination of new data and previously established sample parameters. It is also robust, eliminating cumulative error and error propagation that can cause conventional analysis to fail. An interferometric method for acquiring complex-reflectance data is proposed, although to achieve the necessary level of accuracy with present technology would be a formidable challenge. For ellipsometric measurements these technical obstacles do not exist, but an equivalent exact solution is not possible. However, I develop a common-pseudosubstrate approximation (CPA) that in applications to semiconductor crystal growth is accurate to better than 0.1%. The minimal-data approach also provides new insights about how sample parameters are determined from measured optical functions. For example, to determine deposition rates one needs to establish the second derivative (curvature) as well, which places additional constraints on measurement accuracy and/or the amount of data required. Also, the small-term expansion of the ellipsometrically determined pseudodielectric function 〈∊〉, originally derived as a thin-film limit of the three-phase model, is shown to be more generally valid. This result provides a theoretical basis for the direct analysis of several phenomena, including interface mixing, from 〈∊〉 data obtained during epitaxial growth. Using the CPA, I derive expressions that allow one to assess whether the performance of a given ellipsometer is adequate for growth control. Finally, the influence of selvage layers on determined values of ∊0 is briefly discussed.
124 citations
TL;DR: The transverse instability of laser beams due tocounterpropagation in photorefractive KNbO3 is reported and Hexagonal unstable emission emerges around two counterpropagating pump beams.
Abstract: We report the transverse instability of laser beams due to counterpropagation in photorefractive KNbO3. Hexagonal unstable emission emerges around two counterpropagating pump beams. This emission is in the same linear polarization with the pump beams and is observed in configurations where reflection gratings are dominant.
119 citations
TL;DR: A simple method for phase modulating unpolarized light with a double pass through a nematic liquid crystal retarder is described.
Abstract: A simple method for phase modulating unpolarized light with a double pass through a nematic liquid crystal retarder is described.
118 citations
TL;DR: In this article, the state and degree of polarization of Rayleigh backscattered light in low birefringent optical fibers was calculated using Stokes calculus, and the experimental results agree with the calculations.
Abstract: The state and degree of polarization (SOP, DOP) of Rayleigh backscattered light in low birefringent optical fibers was calculated using Stokes calculus. It was found that the SOP of Rayleigh backscattered light in low birefringent fiber is constant, viz. the same as the SOP of the incoming light. The DOP of Rayleigh backscattered light is one-third of the DOP of the incoming light, and not just anywhere between 0 and 100% as often mentioned in the literature. The experimental results agree with the calculations. >
113 citations
TL;DR: Direct evidence, based on state-of-polarization measurements, that nonlinear polarization evolution is the responsible mode-locking mechanism is also given.
Abstract: A full characterization of a self-starting, passively mode-locked soliton ring fiber laser in terms of its various modes of mode-locked operation, cavity length, and type of fiber used is presented. Direct evidence, based on state-of-polarization measurements, that nonlinear polarization evolution is the responsible mode-locking mechanism is also given.
113 citations
TL;DR: In this article, an all-polarisation preserving actively modelocked erbium doped fiber ring laser was used to generate optical pulses of less than 6ps duration at repetition rates up to 40GHz.
Abstract: Optical pulses of less than 6ps duration have been generated at repetition rates up to 40GHz using an all-polarisation preserving actively modelocked erbium doped fibre ring laser. The wavelength tuning range was 43 nm at this repetition rate and extended over 52nm (1518–1570nm) at 20GHz. Minimisation of the overall ring dispersion offered wavelength tunability at nearly constant repetition rate throughout the whole tuning range.
110 citations
TL;DR: In this article, high visibility (V = 0985) single photon fringe measurements in a 10 km long, optical fibre-based, time and polarisation division Mach-Zehnder interferometer are reported.
Abstract: High visibility (V = 0985) single photon fringe measurements in a 10 km long, optical fibre-based, time- and polarisation-division Mach-Zehnder interferometer are reported The ability of the system to transmit key data in a quantum cryptography scheme is assessed
110 citations
TL;DR: In this article, the four laws of Arago-Fresnel governing the interference of polarized light were determined experimentally from first principles using the spectral representation of stationary stochastic processes and the Jones matrix description of a polarizer.
Abstract: The four laws of Arago–Fresnel governing the interference of polarized light were determined experimentally. Analytical proofs are derived directly from first principles. The technique used for the proofs is that of the spectral representation of stationary stochastic processes in conjunction with the Jones matrix description of a polarizer.
TL;DR: A review of magnetic fields in galaxies can be found in this paper, where the authors summarize the observational evidence and give viable explanations for the magnetic properties of galaxies in terms of the dynamo theory of flat objects.
Abstract: Recent years have seen an amazing development in our knowledge of the magnetic fields in the universe. The last ten years were crucial in our realization of the importance of the magnetic fields in galaxies. While a lot of the earlier data on our Galaxy depended on optical observations, the bulk of the recent results depend on radio measurements. The radio Zeeman effect gave us new information on magnetic fields in molecular clouds. The mapping of galaxies at several radio frequencies resulted in new knowledge about the large-scale magnetic fields in these basic building blocks of the universe. These exciting observations have led to new theoretical developments. In particular, the dynamo theory of flat objects received much attention since the observed large-scale structures can best be explained through the action of the dynamo effect. This review will attempt to summarise the observational evidence and to give viable explanations for the magnetic fields in galaxies.
TL;DR: The study of theEL behavior as a function of the external voltage and the persulphate ion concentration proves that while the amplitude of the EL is proportional to the intensity of the exchanged current, the spectral position is only determined by the applied voltage.
Abstract: In this paper, it is reported that the electroluminescence (EL) of porous silicon shows a reversible spectral shift as large as 270 nm for an external bias variation of 0.6 V. This electroluminescence is obtained upon cathodic polarization of lightly doped n-type porous silicon in contact with aqueous persulphate solutions. The study of the EL behavior as a function of the external voltage and the persulphate ion concentration proves that while the amplitude of the EL is proportional to the intensity of the exchanged current, the spectral position is only determined by the applied voltage
TL;DR: In this paper, a thin optical half-waveplate at 1.55μm, only 14.5μm thick, which is 6.3 times as thin as a zeroth order quartz waveplate, is prepared using fluorinated polyimide.
Abstract: A thin optical half-waveplate at 1.55μm, only 14.5μm thick, which is 6.3 times as thin as a zeroth order quartz waveplate, is prepared using fluorinated polyimide. This material has good flexibility, thickness controllability, and high thermal stability. The retardation of the waveplate was retained after annealing at 350°C for 1 h.
TL;DR: In this paper, the optical polarization properties of radio galaxies with redshifts greater than 0.1 were studied and a strong tendency for the E-vector to be either perpendicular or parallel to the radio axis, and perpendicular to the axis in all the high-redshift galaxies.
Abstract: We review the optical polarization properties of radio galaxies with redshifts greater than 0.1. We find a strong tendency for the E-vector to be either perpendicular or parallel to the radio axis, and perpendicular to the axis in all the high-redshift galaxies. The observed degree of linear polarization is correlated with redshift and radio power, and is anticorrelated with the rest-frame wavelength of the measurement and the radio spectral index. No correlation is found with absolute magnitude. For the high-polarization objects (P≥3 per cent), the polarization also increases with the radio asymmetry parameter Q, which is thought to be related to the interstellar-medium density ratio
TL;DR: In this paper, simple eigenvalue tests are given to ascertain that a given real 4×4 matrix transforms the four-vector of Stokes parameters of a beam of light into the fourvector of the Stokes parameter of another beam, and whether a given 4 × 4 matrix is a weighted sum of pure Mueller matrices.
Abstract: Simple eigenvalue tests are given to ascertain that a given real 4×4 matrix transforms the four‐vector of Stokes parameters of a beam of light into the four‐vector of Stokes parameters of another beam of light, and to determine whether a given 4×4 matrix is a weighted sum of pure Mueller matrices. The latter result is derived for matrices satisfying a certain symmetry condition. To derive these results indefinite inner products are applied.
TL;DR: In this article, an engineered polarization control of surface emitting (SE) lasers based on the observed evidence of the polarization determination is reported. But the authors do not consider the use of polyimide as a stress-enhancing material.
Abstract: The engineered polarization control of surface emitting (SE) lasers, based on the observed evidence of the polarization determination, is reported. Thermally stressed epitaxial layers including an active region are made anisotropic by an elliptically etched substrate structure. This stress causes an anisotropy in optical gain of the active region. The polarization control has been demonstrated with about 80% reproducibility in etched-well-type surface emitting (SE) lasers by employing a thick gold film or a polyimide as a stress-enhancing material. >
TL;DR: By retaining the optical carrier, the new method solves for fundamental quantities-optical electric and magnetic fields in space and time-rather than a nonphysical envelope function, and has the potential to provide an unprecedented two- and three-dimensional modeling capability for millimeter-scale integrated- optical circuits with submicrometer engineered inhomogeneities.
Abstract: We present what are to our knowledge first-time calculations from vector nonlinear Maxwell's equations of femtosecond soliton propagation and scattering, including carrier waves, in two-dimensional dielectric waveguides. The time integration efficiently implements linear and nonlinear convolutions for the electric polarization, and the nonlinear convolution accounts for two quantum effects, the Kerr and Raman interactions. By retaining the optical carrier, the new method solves for fundamental quantities - optical electric and magnetic fields in space and time - rather than a nonphysical envelope function. It has the potential to provide an unprecedented two- and three-dimensional modeling capability for millimeter-scale integrated-optical circuits with submicrometer engineered inhomogeneities.
TL;DR: P polarization-selective computer-generated holograms with independent phase profiles for the two orthogonal linear polarizations with first-order diffraction efficiency varied from 6% to 25%, with as much as 40:1 contrast between polarizations.
Abstract: We demonstrate polarization-selective computer-generated holograms with independent phase profiles for the two orthogonal linear polarizations The holograms are made of two surface-relief-etched birefringent substrates joined face to face We describe their design and fabrication and present experimental results for dual binary-phase computer-generated holograms fabricated in lithium niobate The first-order diffraction efficiency varied from 6% to 25%, with as much as 40:1 contrast between polarizations Such elements can be used in compact optoelectronic systems or combined with electro-optic polarization rotators to make electrically controlled optical elements
TL;DR: In this article, numerical hydrodynamics simulations are presented of X-ray heated winds believed to form the "mirrors" which reflect light from obscured Seyfert galaxy nuclei into our line of sight.
Abstract: Numerical hydrodynamics simulations are presented of X-ray heated winds believed to form the 'mirrors' which reflect light from obscured Seyfert galaxy nuclei into our line of sight. Above a likely range of parameters, it is shown that steady state flows are created when a cool torus surrounds an AGN. Some of the mass evaporated off the inner edge of the torus is captured by the central gravitational well, while the rest is driven off in a warm wind. When the central gravity is strong relative to the radiative heating rate, i.e., L/L(E) is small, nearly all the injected matter is captured. When the gravity is weaker, a given combination of heating rate and injected pressure leads to a maximum mass loss rate; when the rate at which mass is injected exceeds this amount, the excess is captured. The dividing line between these two cases comes at L/L(E) = about 0.08.
TL;DR: In this article, a multichannel frequency conversion using four-wave mixing is demonstrated using a polarisation independent configuration, by which polarisation control for each signal is not necessary.
Abstract: Multichannel frequency conversion is demonstrated using fourwave mixing. A polarisation independent configuration is employed, by which polarisation control for each signal is not necessary. By setting the pump light frequency at the zero-dispersion wavelength of the fibre, three FSK modulated signals with a frequency spacing of 70 GHz are simultaneously converted with an equal efficiency of −27.5dB. Bit error rate measurements confirm the feasibility of this conversion scheme.
TL;DR: In this paper, the long term performance measurement shows BER fluctuation, which can be correlated to the fading of the optical signal-to-noise ratio presumably due to the polarisation effect.
Abstract: 4500 km optical fibre transmission at 5 Gbit/s was successfully carried out using 138 erbium-doped fibre amplifiers. However, the long term performance measurement shows BER fluctuation. It is found that such BER fluctuation can be correlated to the fading of the optical signal-to-noise ratio presumably due to the polarisation effect.
TL;DR: This work has succeeded in experimental observation, for the first time, or noncollinear SHG due to a five-wave mixing process according to a scheme 2ω=3ω-ω, governed by a fourth-order susceptibility tensor χ (4)DD.
Abstract: Molecular left-right asymmetry is an origin of nonvanishing even-order optical nonlinear susceptibilities of nonracemic solutions of chiral molecules. Though second harmonic generation (SHG) due to quadratic dipolar nonlinearity is still symmetry forbidden in optically active liquids yet we have succeeded in experimental observation, for the first time, of noncollinear SHG due to a five-wave mixing process according to a scheme 2\ensuremath{\omega}=3\ensuremath{\omega}-\ensuremath{\omega}, governed by a fourth-order susceptibility tensor ${\mathrm{\ensuremath{\chi}}}^{(4)\mathit{D}}$. The SHG signal is found to be well collimated and quasi-phase-matched; it shows theoretically predicted polarization, intensity, spectral, and temporal properties.
TL;DR: In this article, the authors present the data from 3 years of monitoring the optical polarization and apparent brightness of 37 X-ray-selected BL Lacertae objects, including a complete sample drawn from the Einstein Extended Medium Sensitivity Survey.
Abstract: We present the data from 3 years of monitoring the optical polarization and apparent brightness of 37 X-ray-selected BL Lacertae objects. The monitored objects include a complete sample drawn from the Einstein Extended Medium Sensitivity Survey. We confirm the BL Lac identifications for 15 of these 22 objects. We include descriptions of the objects and samples in our monitoring program and of the existing complete samples of BL Lac objects, highly polarized quasars, optically violent variable quasars, and blazars.
TL;DR: In this article, images of stress distributions in GaAs-based diode lasers have been obtained using scanned polarization-resolved photoluminescence, and measured stress distributions due to ridge structures, metallization, applied force, and bonding are presented.
Abstract: Images of stress distributions in GaAs-based diode lasers have been obtained using scanned polarization-resolved photoluminescence. A stress resolution of about 10/sup 7 /dyn/cm/sup 2 /and a spatial resolution of about 1 mu m have been obtained. The experimental technique is described, and measured stress distributions due to ridge structures, metallization, applied force, and bonding are presented. >
TL;DR: An integrated InGaAsP/InP wavelength demultiplexer operating around 1.5 μm wavelength, using total internal reflection from dry-etched collimating mirrors and transmission grating, has been realized in polarisation insensitive symmetrical slab waveguide as mentioned in this paper.
Abstract: An integrated InGaAsP/InP wavelength demultiplexer operating around 1.5 μm wavelength, using total internal reflection from dry-etched collimating mirrors and transmission grating, has been realised in polarisation insensitive symmetrical slab waveguide. The device exhibits polarisation dispersion that equates to less than 1 nm spectral dispersion, losses down to 7.2 dB and crosstalk less than –20 dB.
TL;DR: In this article, the conversion of a linear polarized laser beam into a point symmetric beam with linear dependence of the polarization direction on the angular position in the beam is described, based on the combination of two circular polarized beams with linear phase-angular dependence.
TL;DR: In this paper, a femtosecond erbium-doped fiber laser with nonlinear polarisation rotation is presented, in which a polariser is installed at a point-symmetric position against a polarisation-sensitive optical isolator in the ring laser cavity.
Abstract: A new type of femtosecond erbium-doped fibre laser with nonlinear polarisation rotation is presented, in which a polariser is installed at a point-symmetric position against a polarisation-sensitive optical isolator in the ring laser cavity This technique enables us to remove the continuum (DC component) in the oscillation waveform completely and to obtain a stable pulse train as short as 136–145 fs with a 56 MHz repetition rate
TL;DR: In this article, the authors describe sharp Brewster modes near longitudinal frequencies in p-polarized oblique incidence reflectivity and give details of guided wave and surface modes, including interface polaritons at the superlattice-vacuum interface.
Abstract: In the far infrared, superlattice dielectric functions can be well represented by an effective-medium model. The overall symmetry of a superlattice is uniaxial, and each of the principal components of the resulting dielectric tensor typically contains a different series of resonances. Here we examine some consequences that are of importance to many of the spectroscopy experiments that are undertaken. We describe sharp Brewster modes near longitudinal frequencies in p-polarized oblique incidence reflectivity and give details of guided wave and surface modes, including interface polaritons at the superlattice–vacuum interface. After discussing the basic optical principles we examine their application to the measurement of phonon confinement parameters.
TL;DR: In this article, the authors investigated the polarization properties of a vertical cavity surface emitting laser that uses an (Al 0.5Ga0.5As) 1/2(GaAs)1/2 fractional layer superlattice (FLS) as an anisotropic gain medium.
Abstract: We investigate the polarization properties of a vertical cavity surface emitting laser that uses an (Al0.5Ga0.5As)1/2(GaAs)1/2 fractional‐layer superlattice (FLS) as an anisotropic gain medium. The anisotropy in the gain enables us to both control and switch the polarization state of the optically pumped lasing output. We obtain room‐temperature lasing for wavelengths from 690 to 720 nm. The output is linearly polarized and the polarization direction is fixed, either parallel or perpendicular to the FLS layers. By tuning the cavity resonance wavelength, we demonstrate high contrast switching between two orthogonal linear polarization states in the FLS surface emitting laser.