Optical polarization

About: Optical polarization is a research topic. Over the lifetime, 13992 publications have been published within this topic receiving 244284 citations.

Optical polarimetry of random fields.

Abstract: The state of polarization of an optical field provides detailed information concerning both the radiation emission processes and the intricate interaction between light and matter. We report here a novel approach for characterizing the polarization properties of electromagnetic fields for which the electric field vector at a point may fluctuate in three dimensions. Using probes which couple all three components of the field, we were able to extract the polarized and unpolarized components of such fields. Our results constitute the proof of concept for what could be called three-dimensional optical polarimetry.

Structure of matrices for the transformation of laser radiation by biofractals

Abstract: The changes in the state of polarisation of laser radiation transformed by biofractal objects are examined. The orientational angular structure of the matrix elements of the operator representing the optical properties of biofractals with different morphological structures (mineralised collagen fibres and myosin bundles) is investigated. An optical model for the description of fractal laser fields under the conditions of single light scattering is proposed.

Design of optical polarization splitters in a single-section deeply etched MMI waveguide

Abstract: The design of a single-section polarization splitter in a deeply etched semiconductor MMI waveguide is presented. Numerically simulated results indicate that the semiconductor MMI exhibits considerable polarization dependence and, utilizing this effect, a compact 1.6-mm-long polarization splitter may be fabricated to yield more than 8-dB polarization separation and only 0.11-dB optical loss, using a very simple design-approach.

Vacuum polarization effects on radiative opacities in a strong magnetic field

Abstract: We study the electromagnetic properties of plasmas allowing for the polarization effect of the vacuum induced by the presence of a strong external magnetic field. Adopting the cold-plasma polarization tensor to account for the electron component, we find that the polarization properties and transport of x-ray radiation can be severely altered by the magnetic vacuum effects. The effect becomes important at relatively high frequencies, $\frac{\ensuremath{\omega}}{{\ensuremath{\omega}}_{p}}\ensuremath{\gtrsim}{(\frac{15\ensuremath{\pi}}{\ensuremath{\alpha}})}^{\frac{1}{2}}$ $\frac{{B}_{c}}{B}$ where ${\ensuremath{\omega}}_{p}={(4\ensuremath{\pi}{n}_{e}\frac{{e}^{2}}{m})}^{\frac{1}{2}}$ is the plasma frequency of the electron component, $\ensuremath{\alpha}$ is the fine-structure constant, and ${B}_{c}=\frac{{m}^{2}{c}^{3}}{e\ensuremath{\hbar}}\ensuremath{\simeq}4.4\ifmmode\times\else\texttimes\fi{}{10}^{13}$ G is the electrodynamic critical field. For typical pulsar magnetic fields, $B\ensuremath{\sim}0.1$ ${B}_{c}$, and x-ray frequencies, this condition is satisfied even for relatively high plasma densities ${n}_{e}\ensuremath{\sim}{10}^{23}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. Whenever the above inequality is fulfilled the vacuum effect dominates the polarization properties of the normal modes of the medium, giving rise to a significant change in the medium opacity. The Thomson, bremsstrahlung, and cyclotron opacities are thus significantly altered from their usual cold-plasma values. The largest departures are found in the vicinity of the electron gyrofrequency, where the vacuum induces a strongly anisotropic resonant behavior on the ordinary mode (which is nonresonant in the usual cold-plasma circumstances). This property may be significant in analyzing the polarization and spectral character of the cyclotron feature in Hercules X-1 and other accreting x-ray pulsars.

Dust formation in the ejecta of the type II-P supernova 2004dj

Abstract: Aims. Core-collapse supernovae (CC SNe), especially type II-Plateau ones, are thought to be important contributors to cosmic dust production. SN 2004dj, one of the closest and brightest SN since 1987A, offered a good opportunity to examine dust-formation processes. To find signs of newly formed dust, we analyze all available mid-infrared (MIR) archival data from the Spitzer space telescope. Methods. We re-reduced and analyzed data from IRAC, MIPS, and IRS instruments obtained between +98 and +1381 days after explosion and generated light curves and spectra for each epoch. Observed spectral energy distributions are fitted with both analytic and numerical models, using the radiative-transfer code MOCASSIN for the latter ones. We also use imaging polarimetric data obtained at +425 days by the Hubble space telescope. Results. We present convincing evidence of dust formation in the ejecta of SN 2004dj from MIR light curves and spectra. Significant MIR excess flux is detected in all bands between 3.6 and 24 μm. In the optical, a ∼0.8% polarization is also detected at a 2-sigma level, which exceeds the interstellar polarization in that direction. Our analysis shows that the freshly-formed dust around SN 2004dj can be modeled assuming a nearly spherical shell that contains amorphous carbon grains, which cool from ∼700 K to ∼400 K between +267 and +1246 days. Persistent excess flux is found above 10 μ m, which is explained by ac old (∼115 K) dust component. If this cold dust is of circumstellar origin, it is likely to be condensed in a cool, dense shell between the forward and reverse shocks. Pre-existing ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ––– – +++ –– –––– –