Circular polarization

About: Circular polarization is a research topic. Over the lifetime, 15201 publications have been published within this topic receiving 234418 citations.

Polarization measurements through space-to-ground atmospheric propagation paths by using a highly polarized laser source in space

Abstract: The polarization characteristics of an artificial laser source in space were measured through space-to-ground atmospheric transmission paths. An existing Japanese laser communication satellite and optical ground station were used to measure Stokes parameters and the degree of polarization of the laser beam transmitted from the satellite. As a result, the polarization was preserved within an rms error of 1.6°, and the degree of polarization was 99.4±4.4% through the space-to-ground atmosphere. These results contribute to the link estimation for quantum key distribution via space and provide the potential for enhancements in quantum cryptography worldwide in the future.

Giant asymmetric transmission of circular polarization in layer-by-layer chiral metamaterials

Abstract: In this paper, two kinds of bi-layered chiral metamaterials were proposed to enhance the asymmetric transmission effects for circular polarized electromagnetic waves which are only found in planar chiral metamaterials according to previous studies. It was found that the magnitude of the asymmetric transmission parameters mainly depends on the distances between the two metal layers. With appropriate distance, the asymmetric transmission parameter for circular polarized electromagnetic waves can increase to 0.6. Moreover, both proposed configurations show no asymmetric transmission for linear polarized electromagnetic waves which is widely studied in other bi-layered metamaterials.

Polarization diffraction grating produced by femtosecond laser nanostructuring in glass

Abstract: We demonstrate polarization sensitive diffractive optical element fabrication by femtosecond direct writing in the bulk of silica glass. Modulation of the anisotropic properties is produced by controlling light-induced self-assembled nano-gratings.

Circular polarization of water masers in the circumstellar envelopes of late type stars

Abstract: We present circular polarization measurements of circumstellar H2O masers. The magnetic fields in circumstellar envelopes are generally examd. by polarization observations of SiO and OH masers. SiO masers C probe the high temp. and d. regime close to the central star. OH masers are found at much lower densities and temps., generally much further out in the circumstellar envelope. The circular polarization detected in the (616-523) rotational transition of the H2O maser can be attributed to Zeeman splitting in the intermediate temp. and d. regime. The magnetic fields are derived using a general, LTE Zeeman anal. as well as a full radiative transfer method (non-LTE), which includes a treatment of all hyperfine components simultaneously as well as the effects of satn. and unequal populations of the magnetic substates. The differences and relevances of these interpretations are discussed extensively. We also address a non-Zeeman interpretation as the cause for the circular polarization, but this is found to be unlikely. We favor the non-LTE anal. The H2O masers are shown to be unsatd., on the basis of their line widths and the lack of linear polarization. The field strengths are compared with previous detections of the magnetic field on the SiO and OH masers. Assuming a r-2 dependence of the magnetic field on the distance to the star, similar to a solar-type magnetic field, our results seem to indicate that we are probing the highest d. maser clumps at the inner edge of the H2O maser region. This allows us to est. the d. of the clumps, and the extent of the H2O maser region. We show that the magnetic pressure dominates the thermal pressure by a factor of 20 or more. We also give an order of magnitude est. of the magnetic field on the surface of the stars. In particular we discuss the differences between supergiants and Mira variable stars. [on SciFinder (R)]

Patterns and properties of polarized light in air and water.

Abstract: Natural sources of light are at best weakly polarized, but polarization of light is common in natural scenes in the atmosphere, on the surface of the Earth, and underwater. We review the current state of knowledge concerning how polarization and polarization patterns are formed in nature, emphasizing linearly polarized light. Scattering of sunlight or moonlight in the sky often forms a strongly polarized, stable and predictable pattern used by many animals for orientation and navigation throughout the day, at twilight, and on moonlit nights. By contrast, polarization of light in water, while visible in most directions of view, is generally much weaker. In air, the surfaces of natural objects often reflect partially polarized light, but such reflections are rarer underwater, and multiple-path scattering degrades such polarization within metres. Because polarization in both air and water is produced by scattering, visibility through such media can be enhanced using straightforward polarization-based methods of image recovery, and some living visual systems may use similar methods to improve vision in haze or underwater. Although circularly polarized light is rare in nature, it is produced by the surfaces of some animals, where it may be used in specialized systems of communication.