Polarization Ellipse Research Articles

Light-wave polarization bistability in a gyrotropic magnetic medium

A linearly polarized light wave enters a Fabry–Pérot cavity containing a MnSe/ZnTe superlattice. The helical axis is perpendicular to the cavity walls, and an external magnetic field is parallel to that axis. The coherence matrix is calculated and the polarization state of the outgoing beam is determined. It is shown that the ratio of the semi-axes of the polarization ellipse and the spatial orientation of the ellipse major axis as functions of the incoming light intensity exhibit bistable behaviour.

Heavy-hole and light-hole quantum beats in the polarization state of coherent emission from quantum wells

Dual-channel spectral interferometry is used to measure the vectorial dynamics of the the four-wave-mixing signal from a GaAs-AlGaAs multiple quantum well when both heavy-and light-hole excitons are excited. The ellipticity, the orientation, and the sense of rotation of the polarization ellipse associated with this emission are observed to oscillate dramatically at the heavy-hole-light-hole quantum beat frequency. The qualitative nature of the beating can be described by a simple model based on the density matrix equations for two independent three-level systems without the inclusion of many body effects; however, these beats are superposed on a polarization that is dominated by many-body effects.

Nonlinear Kerr effect in magnetic crystals

The reflection of an intense light wave from the boundary of a semiinfinite magnetic crystal is investigated theoretically. Expressions are obtained for the rotation angle of the polarization ellipse and the degree of ellipticity of the reflected wave as a function of the polarization of the incident radiation. The physical wave-interaction mechanisms that give rise to this effect are established.

Polarimetry of scattered light using heterodyne detection

Abstract Heterodyne detection has been used to measure the polarization state of light back-scattered from various targets (including flame-sprayed aluminium, sandpaper and painted surfaces). The samples are illuminated with a linearly polarized single-frequency continuous-wave CO2 laser operating at a wavelength of 10.6 μm. The back-scattered co-polarized and cross-polarized components are both coherently detected by beating with an optical local oscillator. This process allows the relative amplitudes and phases of the two components to be measured and hence the light's polarization state can be evaluated. When the target undergoes movement, the scattered light demonstrates the usual properties of dynamic speckle, and the technique allows observation of the time evolution of the polarization ellipse.

Polarimetry of scattered light using heterodyne detection

Heterodyne detection has been used to measure the polarization state of light back-scattered from various targets (including flame-sprayed aluminium, sandpaper and painted surfaces). The samples are illuminated with a linearly polarized single-frequency continuous-wave CO2 laser operating at a wavelength of 10.6 μm. The back-scattered co-polarized and cross-polarized components are both coherently detected by beating with an optical local oscillator. This process allows the relative amplitudes and phases of the two components to be measured and hence the light's polarization state can be evaluated. When the target undergoes movement, the scattered light demonstrates the usual properties of dynamic speckle, and the technique allows observation of the time evolution of the polarization ellipse.

Real Time Optics of Amorphous Silicon Solar Cellfabrication on Textured Tin-Oxide-Coated Glass

AbstractA rotating-compensator multichannel ellipsometer has been used to measure the four spectra (1.4-4.0 eV) that describe the Stokes vector of the light beam reflected from the surface of an amorphous silicon (a-Si:H) p-i-n solar cell during fabrication on textured tin-oxide (SnO2) coated glass. The Stokes vector elements include the irradiance in the reflected beam (or the reflectance) and the parameters {(Q, χ), p} of the reflected beam, where Q and χ are the tilt and ellipticity angles of the polarization ellipse and p is the degree of polarization. The value of p deviates from unity in part due to the non-uniform nature of the textured SnO2 substrate film. An analysis of Q and χ that neglects the effects of the texture can provide the time evolution of the thicknesses, microscopic structure, and the optical properties of the component layers of the a-Si:H solar cell. Deviations of the measured reflectance spectra from those predicted on the basis of the (Q, χ) analysis provide the thickness dependence of the scattering and the evolution of the macroscopic structure of the solar cell. The measurement and analysis approach is important because of its potential application for real time monitoring of solar cell production. The analysis results also provide realistic inputs for optical modeling of the effects of texture in light trapping for solar cell efficiency enhancement.

Tunable polarization response of a planar asymmetric-spiral infrared antenna

We present measurements at 10.6 microm that demonstrate electronic tuning of the polarization response of asymmetric-spiral infrared antennas connected to Ni-NiO-Ni diodes. Continuous variation of the bias voltage applied to the diode results in a rotation of the principal axis of the polarization ellipse of the spiral antenna. A 90 degrees tuning range is measured for a bias voltage that varies from -160 to +160 mV .This effect is caused by a small asymmetry of the deposited diode contact or by a variation of the detector capacitance with the applied bias voltage.

Ultrafast time-resolved quantum beats in the polarization state of coherent emission from quantum wells

Dual-channel spectral interferometry is used to measure the ellipticity, the orientation of the polarization ellipse, and the sense of rotation of the four-wave-mixing signal from a GaAs-AlGaAs multiple quantum well. Each parameter is observed to oscillate dramatically at the heavy-hole-light-hole quantum beat frequency. During each beat period (in the strong quantum beat regime), the ellipticity oscillates twice between linear and almost-circular polarization, the orientation of the polarization ellipse rotates through a complete 180 degrees , and the sense of rotation changes from left- to right-circular polarization.

Polarization of radiation amplified by dye solutions

Experimental investigations of the change of polarization state of probing radiation on passing through anisotropically excited solutions of rhodamine 6G and 3,6-tetramethyldiamino-N-methylphthalimide in glycerol were carried out. These investigations allowed us to find the phase anisotropy in these molecular systems. The parameters of the polarization ellipse (the ratio of axes , orientation, direction of rotation) were determined. The main factors (the intensity and orientation of the polarization plane of the probing radiation) influencing these parameters were established. The differences between the refractive indices were designed with the help of the obtained parameters of the polarization ellipse. The spectral behaviour of the amplitude and phase anisotropy for the long-wavelength band of absorption and fluorescence was studied and described qualitatively. The features of the spectral behaviour of for the indicated solutions, which are modelled by different systems of energy levels of the active molecules, were established.

The Majorana representation of polarization, and the Berry phase of light

A natural geometric representation of the polarization of light with fixed propagation direction is a dot on a sphere in an abstract space: the Poincaré sphere. If the direction of propagation is also included as a variable, a different description, given here, is natural. It is taken from quantum mechanics (from the Majorana picture of a spin system), spin one in the case of light. It characterizes polarized light by two dots on a unit sphere in the real space of directions (i.e. by two unit vectors). The direction of propagation is their bisector (or its reverse). Projecting the two dots onto the plane perpendicular to this direction gives the two foci of the polarization ellipse (which lies in this plane and has a unit semimajor axis). As an application of this picture the geometric Berry phase for light is calculated. The result accords with the quantum spin-1 formula of Bouchiat and Gibbons, and with the prescription for finding the geometric phase for light given by Bhandari.

Polarization partition noise and intensity fluctuation linewidth in a nearly symmetric vector laser

We consider the statistical properties of the fluctuations in the orientation of the vector laser field for a nearly isotropic laser, addressing the competition between the randomizing influence of noise and the preference for linearly or circularly polarized emission induced by saturation in the laser medium and/or cavity anisotropies. We describe, through a nonperturbative analysis, a crossover regime from diffusion-induced polarization-isotropic emission to emission of nearly fixed polarization characteristics. In this crossover the linewidth of intensity fluctuations associated with one of the circularly polarized components of the vector field amplitude changes from decreasing to increasing with output power. This behavior can be expressed in terms of a single parameter that measures the pump or the total output intensity in terms of the ratio of the noise amplitude to the degree of cross saturation of the amplitudes of the circularly polarized components of the vector field amplitude. Analytical results are given for the linewidth of the intensity fluctuations. When the laser has a preference for linearly polarized emission, there is a weakly non-Lorentzian spectrum in the crossover region. When the laser has a ``preference'' for circularly polarized emission the crossover regime is characterized by a non-Lorentzian spectrum due to fast hopping between two circularly polarized eigenstates. We also describe ellipticity fluctuations induced by the diffusion of the direction of the main axis of the polarization ellipse in the presence of cavity birefringence.

The Majorana representation of polarization, and the Berry phase of light

Abstract A natural geometric representation of the polarization of light with fixed propagation direction is a dot on a sphere in an abstract space: the Poincaré sphere. If the direction of propagation is also included as a variable, a different description, given here, is natural. It is taken from quantum mechanics (from the Majorana picture of a spin system), spin one in the case of light. It characterizes polarized light by two dots on a unit sphere in the real space of directions (i.e. by two unit vectors). The direction of propagation is their bisector (or its reverse). Projecting the two dots onto the plane perpendicular to this direction gives the two foci of the polarization ellipse (which lies in this plane and has a unit semimajor axis). As an application of this picture the geometric Berry phase for light is calculated. The result accords with the quantum spin-1 formula of Bouchiat and Gibbons, and with the prescription for finding the geometric phase for light given by Bhandari.

Polarization of the 61st harmonic from 1053-nm laser radiation in neon

We report the polarization measurement of a very high order (59th and 61st order, $\ensuremath{\sim}$17 nm) harmonic. A Mo-Si multilayer mirror is used as a polarizer with reflectivity of 60% and polarization analyzing power close to unity around a wavelength of 17 nm. We observe that for these high harmonics in Ne there is no rotation of the polarization ellipse with respect to the fundamental laser polarization, even though the harmonics are in the plateau. For linear and slightly elliptical laser polarization the harmonics still remain linearly polarized. These findings are supported by a full theoretical simulation, which includes spatiotemporal integration and phase matching of the emitted harmonic radiation.

Effect of limiting polarization in the Jovian inner magnetosphere

Jovian decameter emission is known to exhibit almost total polarization. We consider the elliptical polarization to be a consequence of linear-mode coupling in the Jovian magnetosphere outside the source region. We determine conditions of emission propagation along the ray path that are necessary for self-consistent explanatation of the polarization observations and show that the ellipticity (axial ratio of the polarization ellipse) is determined by the magnetospheric plasma density ne in a small region a distance of about half the Jovian radius from the radiation source. The plasma density in the region is quite low, ne<0.4 cm−3, and the geometrical-optics approximation of emssion propagation in front of the region converts to the vacuum approximation behind it. The latter means that the linear-mode coupling in the Jovian inner magnetosphere is manifested as the effect of limiting polarization. Sources of decameter emission emitting at different frequencies f are located at heights corresponding to gyrofrequency levels f Be ≅f and at magnetic-force lines that belong to L-shells passing through the satellite Io. The location of the transitional region in the Jovian magnetosphere varies depending on the emission frequency and the time. For each given decameter radio emission storm occupying some region in frequencytime space, we have a number of transitional regions located in a certain region of the Jovian magnetosphere—the interaction region of the magnetosphere (IRM) for the given emission storm. The distribution of magnetospheric plasma in an IRM is found from data of observations of the polarization ellipiicity of the given decameter radio emission storm. By matching the calculated ellipticity of emission with the observed ellipticity at every point of frequency-time space of the emission dynamic spectrum one finds a recurrent relation between the local values of the magnetospheric plasma density Nc and the planetary magnetic field B in the IRM, which allows evaluation of the distribution of plasma density if a definite model of the Jovian magnetic field has been adopted.

Elliptic polarization of the refracted wave in presence of inhibited reflection

In the present paper we show that when a linearly polarized wave is incident on an uniaxial crystal–isotropic medium interface, the refracted ray is elliptically polarized when the incidence angle is greater than the limiting one of inhibited reflection. We also calculate the eccentricity of the ellipse of polarization and the angle between its major axis with the incidence plane.

Peculiarities of spontaneous-grating formation in light-sensitive films under elliptically polarized laser radiation

The formation of spontaneous gratings in thin waveguide AgCl–Ag photosensitive films was studied under elliptically polarized laser radiation. New peculiarities of the gratings growth were found (i) a deviation in angular position of the wave vectors of the most probable microgratings from π / 2 about the major axis of the polarization ellipse; and (ii) an asymmetry, which depends on the ellipticity sign, in the diffraction and small-angle scattering patterns. The experimental results are explained within the framework of a model that shows the scattering of incident light by small prolate absorptive Ag spheroids oriented across the major axis of the ellipse and arising from the stage of photoinduced dichroism that precedes grating formation. We show that the dependence of the diffraction patterns' asymmetry on the ellipticity sign is related to an instability due to the angular position of the wave vectors of the most probable microgratings. PACS No. 78.65

Parameters for polarization gradients in three-dimensional electromagnetic standing waves

The electric field polarization structure of three-dimensional monochromatic electromagnetic fields is investigated, with particular reference to the three-dimensional standing waves that are commonly used in laser cooling. Two parameters are introduced for describing the polarization at a field point, one of which is a generalization of the Stokes ellipticity parameter while the other describes the rotation of linear polarization (or the polarization ellipse) for small displacements. The two parameters are shown to be simply related to the density and flux of intrinsic angular momentum (spin) in the field. Additional parameters are introduced to provide measures of the polarization gradients on straight line trajectories in three-dimensional standing waves and the implications for laser cooling are discussed.

Delineation of near‐surface structures using VLF and VLF-R data ‐ An insight from the joint inversion results

Very low frequency (VLF) electromagnetic measurements are generally used to study the variations in electrical conductivity in the upper few hundred meters of the Earth’s crust. The VLF magnetic field mode, in which the tilt angle and ellipticity of the magnetic polarization ellipse, i.e., the real and imaginary anomalies respectively, are measured, has been widely used for more than 30 years. The VLF resistivity mode (VLF-R), in use since the late 1960s, is, in principle, nothing but a high frequency magnetotelluric method in which the apparent resistivity and phase are recorded.

Polarization response of asymmetric-spiral infrared antennas

We present measurements on the polarization response of Ni-NiO-Ni diodes coupled to asymmetric spiral antennas. Our data are for the wavelength dependence of the orientation of the major axis of the polarization ellipse over the wavelength range 10.2-10.7 mum. The data are well fit by a two-wire antenna model. We find that the modes excited on the antenna are a combination of the balanced and unbalanced modes of a two-wire lossy transmission line.

The effect of an ionospheric inhomogeneity on magnetic pulsation polarization

Abstract The problem of magnetic disturbance polarization on the ground for a dipole source in the inhomogeneous ionosphere is solved for two kinds of an horizontal inhomogeneity. One is the case when the ionosphere is separated into two distinct parts with different conductivities and the other is a mesoscale strip in the ionosphere strip with enhanced conductivity which may be associated with an auroral arc. By using the ‘method of reflection’ an electric potential of the polarization field and a current function of the equivalent ionospheric currents are found for these cases. The distributions of the magnetic disturbance polarization ellipses on the ground have been obtained. It is found that under the certain ionospheric conditions the inhomogeneity can cause a significant (up to 40%) contribution to the magnetic disturbance amplitude on the ground and change essentially its polarization. For the first case the contribution of the inhomogeneity to magnetic variations on the ground is symmetric relative to the boundary. This boundary separates the regions with different rotation sense of the magnetic disturbance vector. For the case of the meso-scale strip, it is found that on the ground the magnetic polarization ellipse distribution becomes asymmetric and complicated. The line separating the regions with different rotation sense becomes curved.