Electro-optic modulation of light propagating near the optic axis with any polarization in uniaxial crystals

The electro-optic effect in uniaxial crystals for light propagating near the optic axis with any polarization has been analyzed. The passive and the electrically induced birefringences and the rotation of polarization direction in crystals have been calculated, and the conoscopic interference figures under orthogonal polariscopes for different polarizer directions have been plotted. The extinction areas caused by the rotation of polarization direction in crystals change with the polarizer direction, but the two heads of the induced optical axes do not vary, which are always on the induced principal axis with bigger refractive index. The directions of polariscopes are always extinction, and the ±45° directions with polarizer are always complete transmission. The conoscopic interference figures for LiNbO₃ crystals have been demonstrated experimentally by rotating polariscopes directions, which accord with the theoretically calculating plots.     

Self-induced resonant optical rotation in crystals KCl:Li

The specific rotation of the resonant radiation polarization plane predicted earlier for cubic crystals with tunneling centers is observed in KCl containing F_A(Li) centers. The rotation is supposed to be connected essentially with the well-known off-center position of Li⁺ ion. The simple theory based on this assumption agrees with the experimental data.     

Self-induced optical activity in crystals

We have observed non-linear rotation of the plane of polarization of a linearly polarized light beam in GaAs crystals ($\text{4}$3m). The effect has been investigated by means of YAG : Nd^3- laser and pulse polarimeter with accuracy to non-linear rotation angle 0.02°. Two mechanisms caused by the non-linearity of the spatial dispersion and the anisotropy of two-photon's absorption have been distinguished and corresponding susceptibilities have been calculated.     

Experimental indication of macroscopic polarization parallel to the tilt plane in free-standing films of ferroelectric liquid crystals 8SI* and DOBAMBC

Optical reflectivity and x-ray studies have been conducted on free-standing films and bulk samples of ferroelectric liquid crystals near the smectic-A-smectic-C ^* transition. A tilt plane rotation with respect to the direction of an applied electric field is found in the ferroelectric films above the bulk transition temperature. Whereas the macroscopic polarization is perpendicular to the tilt plane at low temperature, it is parallel to the tilt plane at elevated temperature. The temperature dependence of the average tilt angle is measured. Zh. éksp. Teor. Fiz. 116, 1329–1334 (October 1999) Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor.     

Orientational optical unsteady effects in rare-earth garnet crystals containing chromium or vanadium ions with the electronic 3d 2 configuration

The method of picosecond unsteady spectroscopy was used to study the optical anisotropy manifested in rare-erath garnet crystals doped by chromium and vanadium. In YAG:V³⁺, GSAG:V³⁺ and YAG;Cr⁴⁺ crystals the anisotropy of unsteady absorption and the effect of rotation of the plane of polarization of a probing pulse pulve were revealed. Deceased. Research Institute of Applied Physics at the Irkutsk State University, 20, Gagarin Ave., Irkutsk, 664003, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 597–600, July–August, 1998.     

双折射双频激光器输出光偏振特性的实验研究

报道了双折射双频激光器输出光偏振特性的实验研究，实验发现双折射双频激光器两端输出的线偏振光的偏振方向并不一致，而相互有一定的旋转角度，实验也再次证明了激光器输出的是正交线偏振光，而不是晶体本征模的椭圆化了的偏振光。     

The correlation between frequency difference and mode polarization in an intracavity birefringent dual-frequency laser

We discuss the correlations between the measured lasing-mode frequency difference and the mode polarization angle in an intracavity birefringent dual-frequency laser. The frequency difference and polarization are adjusted by rotating an intracavity quartz crystal through a large angular range. We propose two kinds of frequency difference: the equal-order frequency difference and the adjacent frequency difference. By measuring the equal-order frequency difference versus the quartz crystal rotation angle, the real physical process behind frequency splitting is revealed. Based on this, the adjacent frequency difference curve is also obtained. The emitted laser beam polarization angle is also measured for large rotations of the intracavity quartz crystal. These measurements reveal the complete process of optical activity in frequency splitting and allow us to predict the trends of frequency difference and polarization angle for large quartz crystal rotation angles. We analyze the correlations between the equal-order frequency difference and the polarization angle based on the experimental results, which show that the certain points on the two curves are inter-related. The principal results agree well with the optical theory of crystals.     

Quasi-phase matching in LiNbO3 using nonlinear coefficients in the XY plane

We report quasi-phase-matched second-harmonic generation in periodically poled lithium niobate (PPLN), where both fundamental and second-harmonic waves are ordinary waves. It provides a lower-limit value for d₂₂ of 1.1 pm/V. The measured temperature and wavelength bandwidth of the second-harmonic signal are in good agreement with the theoretical predictions. Since the d₂₂=d_YYY nonlinear coefficient of LiNbO₃ changes its sign as a result of electric field periodic poling along the Z direction, we deduce that all tensor components of the second-order susceptibility χ⁽²⁾ of trigonal 3m crystals are reversed, thereby expanding the quasi-phase-matching possibilities in these crystals. Furthermore, it enables the realization of all-optical processes based on the nonlinear coefficients in the XY plane, such as all-optical polarization rotation in PPLN, as well as multipartite entanglement experiments based on simultaneous phase matching using different elements of χ⁽²⁾ in a single LiNbO₃ crystal. PACS 42.65.-k; 42.65.Ky; 42.65.Lm     

Untersuchung der Polarisationsebene von Photonen nach Compton-Streuung an polarisierten Elektronen

Two polarization phenomena in Compton scattering by polarized electrons were investigated. In the first experiment, the rotation of the polarization plane of photons passing through magnetized iron and gadolinium was measured. This effect arises from a spin dependence of the Compton forward scattering amplitude. For 228 and 333 keV photons and iron absorbers, the observed rotation angles areφ ₀=(3.90±0.57) ×10^?3 rad · cm^?2 and (4.75±0.58)×10^?3 rad · cm^?2, respectively. Secondly, the orientation of the photon polarization plane after scattering of unpolarized photons by polarized electrons was measured. This experiment tests time reversal invariance in quantum electrodynamics. No dependence of the polarization plane on the direction of the electron spin was found within 2×10^?3.     

Cholesteric liquid crystals with tunable defect inside as polarization azimuth rotation amplifiers and polarization azimuth stabilizers

In the present paper, we investigate the polarization properties of the cholesteric liquid crystals (CLCs) with an isotropic/anisotropic defect inside them, and possibilities of amplification of the polarization plane rotation and stabilization of the light polarization azimuth by these systems are investigated.     

A possible method for measuring the rate of rotation of the plane of polarization of an ultrasonic wave passing through a metal

In this paper, we show that it should be possible to measure the rate of rotation of the plane of polarization of an ultrasonic wave passing through a sample with flat and parallel ends, by making detailed studies of the effects of such rotations on the mechanical resonances of the sample. The plane of polarization is expected to rotate, for example, when the sound wave is passing through pure metal single crystals in the presence of external magnetic fields. Measurements of such rotations can give useful information about the physical properties of the metal.     

Spontaneous periodic structures induced in thin AgCl-Ag films by the continuum in the case of optical rotation of the plane of polarization

The formation of spontaneous periodic structures in thin AgCl-Ag films subject to the continuum (λ≈450–700 nm) in the case of rotation of the plane of polarization with the help of crystalline quartz is studied. The periodic structures are formed due to the excitation of waveguide TE₀ modes in spontaneous Rayleigh scattering of radiation with a wavelength λ incident on the film. The structure periods are smaller than λ and vary in proportion with λ. After special treatment of the irradiated sample (fixing and deposition of an Al layer), periodic structures form a thin reflection hologram capable of reproducing the direction of linear polarization, the angle of optical rotation, and the color of the spectrum recorded. The study of diffraction patterns and small-angle scattering from small portions of a hologram, which were exposed to light with various wavelengths in the recording process, with the help of a probing UV beam (λ_p=337 nm), made it possible to reveal special features of the manifestation of Rayleigh and Wood anomalies associated with the domain structure of PS.     

Production of high circular polarization by ion surface scattering of ferromagnets

From a theoretical analysis we predict large fractions of circular polarization of light emitted by ions scattered from surfaces of ferromagnetic single crystals. Maximum enhancement of circular polarization as compared to surface ion scattering from non-magnetic materials is again expected at grazing incidence. A circular polarization of 89% was estimated for the case of Ar⁺ ions scattered from the (110) plane of a Ni single crystal.     

Photonic density and nonreciprocal optical properties in chiral liquid crystals

Nonreciprocal optical properties of anisotropic (nano-film) heterostructures made of a cholesteric and nematic liquid crystal (CLC-NLC) layers are studied. Namely, a NLC-CLC (and CLC-NLC) structures are considered in which the NLC layer is a quarter-wave plate. The problem is exactly solvable by Ambartsumians’ modified layer addition and Mullers’ transfer-matrix methods. The peculiarities of the polarization dependent properties, such as the photonic density of states, reflection spectra, the polarization plane rotation and ellipticity spectra are investigated. It is shown that such a system canwork as a light modulator, an element for obtaining linearly polarized light with an electrically tunable polarization plane rotation, or a transformer of non-polarized source into linearly polarized light. The analysis of the optical properties in investigated structures can be used for design of perspective optical diodes, microlasers and multifunctional elements on chiral liquid crystals with electrically tunable polarization plane rotation and field controlled light polarization.     

Experimental studies of polarization of laser radiation in a rotating optical glass

The results of experiments on observation of rotation of the plane of polarization of coherent laser radiation with wavelength λ = 0.632991 μm after propagation through a rotating optical disk made of TF3 glass with refractive index n = 1.71250 are analyzed. The experiments were conducted at angle of ray incidence on the flat disk surface ?₀ = 60°, and the rotational speed of the disk was varied from 0 to 200 Hz in both directions. The results indicate that rotation of optically transparent, homogeneous, and isotropic dielectric causes rotation of linear polarization of the monochromatic electromagnetic plane wave by several tens of degrees. At a rotational speed of 3 Hz, the rotation of polarization reached Δφ = 70° for the vertical component of laser output polarization. The dependences of the angle of rotation of polarization and the degree of polarization of the rays on rotational speed are nonlinear and are attributed to the appearance of substantial anisotropic properties in a rotating dielectric.     

Structural and Dielectric Properties of Organic Ferroelectric 2-Methylbenzimidazole

2-methylbenzimidazole single crystals and films are obtained by evaporation from an ethanol solution. The films have a texture with a predominant orientation of the pseudotetragonal axis in the film plane. The blocks are split crystals of the spherulite type, in which the pseudotetragonal axis rotates around the block center. Dielectric hysteresis loops are investigated in the crystals and films in the temperature range of 290–350 K. In the films, loops are observed for both in-plane and out-of-plane electric-field orientation. The maximum value of polarization in the films is close to that observed in single crystals P _s ~ 5 μC/cm². The difference in the temperature behavior of the hysteresis loops in the crystals and films is associated with the specific structure of the blocks.     

A new type of local polariton at the interface of gyrotropic enantiomorphic crystals

It is shown that a new type of local polariton can propagate at the interface of enantiomorphic twins—gyrotropic crystals with left-handed and right-handed rotation of the polarization plane. The wave function of these local polaritons oscillates strongly, with changes of sign, over lengths of the order of the lattice constant near the interface, and the period of the spatial oscillations grows with increasing distance from the interface. The local polariton term is detached from the band of delocalized states toward higher frequencies. Calculations of the radiation broadening of this term show that, for a local polariton, the effect of a giant increase of the decay (“superradiance”) is possible. The magnitude of the polarization rotation due to a local polariton has been found. Fiz. Tverd. Tela (St. Petersburg) 41, 337–340 (February 1999)     

Rotation of the light polarization plane by an ensemble of oriented linear associates: Model representations

In an “oriented gas” model expressions are obtained for the angle of nongyrotropic rotation of the polarization plane (NRPP) of transmitted light by an ensemble of oriented associates consisting of nongyrotropic molecules. The cluster character of the nongyrotropic rotation of the polarization plane and the dependence of its angle on the incident light polarization vector azimuth are noted, which distinguish linear and circular polarization effects. Measurement of linear dichroism by the angle of nongyrotropic rotation of the polarization plane with the use of commercial spectropolarimeters is theoretically justified. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072 Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 95–101, January–February, 1998.     

Rotation of the polarization plane in a gas near resonance

Spectroscopic investigation of the Xe line at λ=5823.89 Å in a gas discharge by measuring the angle of rotation of the polarization plane of the laser radiation passing through a gas-discharge cell in a longitudinal magnetic field is discussed in the paper. An optical scheme of the experiment is described. It is predicted that the sensitivity of this method which implies the measurement of an absorption coefficient is characterized by a value ～10^?9 cm^?1     

双折射晶体中旋光效应的耦合波理论

与传统的旋光效应理论不同，采用三阶赝张量κ⁽²⁾_jkl描述旋光现象，并将相关的电极化强度作微扰处理，直接从Maxwell方程组出发推导出了双折射晶体中自然旋光效应的耦合波方程组并得到解析解.该解析解包含了已有的旋光效应宏观理论结果，可方便地用于描述任意偏振态的单色光波在任意点群的双折射旋光晶体中沿任意方向的传播行为.最后，以石英晶体为例,通过对出射光波的偏振态分析，研究了波矢失配对旋光效应的影响. 关键词： 耦合波理论 旋光效应 非线性光学