Circular polarization

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

Optically controllable THz chiral metamaterials.

Abstract: Switchable and tunable chiral metamaterial response is numerically demonstrated here in different uniaxial chiral metamaterial structures operating in the THz regime. The structures are based on the bi-layer conductor design and the tunable/switchable response is achieved by replacing parts of the metallic components of the structures by photoconducting Si, which can be transformed from an insulating to an almost conducting state through photoexcitation, achievable under external optical pumping. All the structures proposed and discussed here exhibit frequency regions with giant tunable circular dichroism, as well as regions with giant tunable optical activity, showing unique potential in the achievement of active THz polarization components, like tunable polarizers and polarization filters.

MultiFocus Polarization Microscope (MF-PolScope) for 3D polarization imaging of up to 25 focal planes simultaneously

Abstract: We have developed an imaging system for 3D time-lapse polarization microscopy of living biological samples. Polarization imaging reveals the position, alignment and orientation of submicroscopic features in label-free as well as fluorescently labeled specimens. Optical anisotropies are calculated from a series of images where the sample is illuminated by light of different polarization states. Due to the number of images necessary to collect both multiple polarization states and multiple focal planes, 3D polarization imaging is most often prohibitively slow. Our MF-PolScope system employs multifocus optics to form an instantaneous 3D image of up to 25 simultaneous focal-planes. We describe this optical system and show examples of 3D multi-focus polarization imaging of biological samples, including a protein assembly study in budding yeast cells.

Tomographic Reconstruction of Circularly Polarized High Harmonic Fields: 3D Attosecond Metrology

Abstract: Bright, circularly polarized, extreme ultraviolet (EUV) and soft x-ray high-harmonic beams can now be produced using counter-rotating circularly polarized driving laser fields. Although the resulting circularly polarized harmonics consist of relatively simple pairs of peaks in the spectral domain, in the time domain, the field is predicted to emerge as a complex series of rotating linearly polarized bursts, varying rapidly in amplitude, frequency, and polarization. We extend attosecond metrology techniques to circularly polarized light by simultaneously irradiating a copper surface with circularly polarized high-harmonic and linearly polarized infrared laser fields. The resulting temporal modulation of the photoelectron spectra carries essential phase information about the EUV field. Utilizing the polarization selectivity of the solid surface and by rotating the circularly polarized EUV field in space, we fully retrieve the amplitude and phase of the circularly polarized harmonics, allowing us to reconstruct one of the most complex coherent light fields produced to date.

Model for the production of circular polarization via beam-foil interaction

Abstract: Electron capture by protons in the tail of the electron density at a metal surface is investigated. The ion velocity is assumed to be large compared to the velocity of an electron in the lowest orbit of hydrogen. Electron transition probabilities into the 2p states of hydrogen are calculated, analogous to the first Born approximation by extending a model of Trubnikov and Yavlinskii [1] to tilted foils and nonzero angular momentum of the captured electron. From the density matrix the Stokes parameters are calculated. The results give partial agreement with experimental data, especially for the sinusoidal dependence of circular polarization on foil tilt angle.