scispace - formally typeset
Search or ask a question
Topic

Circular polarization

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


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, a detailed account of the evaluation of the electric dipole amplitude induced in alkali one-photon S-S transitions, by the parity violating electron-nucleus short range potential Vp.v.
Abstract: The first part of this paper gives a detailed account of the evaluation of the electric dipole amplitude induced in alkali one-photon S-S transitions, by the parity violating electron-nucleus short range potential Vp.v. associated with the weak neutral currents. Two methods are presented : the first involves an explicit sum over the contributions of the P-states admixed with the S-states and incorporates the best information available on S-P electric dipole amplitudes. The second method, mathematically more elegant, avoids with the help of Green's function techniques any explicit sum over the P states, and, provided that some spin-orbit corrections are neglected, leads to a fairly simple formula involving Coulomb integrals tabulated in the literature and the interpolated quantum defects for S and P waves. The second part is devoted to a description of possible ways to detect parity violation induced in radiative S-S transitions, with a brief discussion of physical processes which could be a source of experimental difficulty. The last section of the paper deals with a theoretical analysis of the influence of a static electric field on the radiative S-S transitions. An evaluation of the induced electric dipole amplitude in the case of cesium indicates that it will compete with the magnetic dipole amplitude for electric fields larger than 10 V/cm. An interference effect between these two amplitudes gives rise to an electronic polarization in the final atomic state proportional to the vector product of the static electric field by the photon momentum which, in a typical case, could be as large as 64 %; the measurement of this interesting and rather peculiar effect will lead to a determination of the sign of the magnetic dipole amplitude. Moreover parity violation could manifest itself by a dependence of this electron polarization on the state of circular polarization of the incident photon.

160 citations

Journal ArticleDOI
TL;DR: A millimeter-wave frequency scanning antenna, which is capable of dynamically changing the state of polarization thereby providing four modes of operation, is investigated and synthesized in the half mode substrate integrated waveguide (HMSIW) technology as mentioned in this paper.
Abstract: A millimeter-wave frequency scanning antenna, which is capable of dynamically changing the state of polarization thereby providing four modes of operation, is investigated and synthesized in the half mode substrate integrated waveguide (HMSIW) technology. This antenna is a planar passive circuit and fabricated by the low-cost PCB process. It is able to operate in either linear or circular polarization (LP or CP), depending on the requirements of its specific application. A wide angular region can be covered by 3 dB beam-widths of the continuous scanning LP beams and CP beams varying the frequency. It has good performance validated by measurements and has nearly a half reduction in size compared with the substrate integrated waveguide (SIW) version. The axial ratios of CP modes are excellent in the main beam directions within whole frequency band of interest and the isolations between each channel are good as well.

159 citations

Journal ArticleDOI
TL;DR: In this paper, the photonic densities of states of two normal light modes for propagation parallel to the helical axis were derived, taking into account multiple reflections due to the finite film thickness, and the influence of the degree of order of the dye's transition dipole moment on the emission characteristics.
Abstract: Due to the sinusoidal modulation of the dielectric properties along the helical axis, cholesteric liquid crystals exhibit a photonic stop band for circularly polarized light, which strongly affects the emission of fluorescent guest molecules. In this paper, we discuss the resulting changes in the emission spectrum. In an analytical treatment, we first derive the photonic densities of states of the two normal light modes for propagation parallel to the helical axis, taking into account multiple reflections due to the finite film thickness. Then we discuss the influence of the degree of order of the dye's transition dipole moment on the emission characteristics. Finally, we present experimental results, which show excellent quantitative agreement with our theoretical description.

158 citations

Journal ArticleDOI
TL;DR: In this paper, a spatiotemporal (ST) optical vortex with a controllable purely transverse orbital angular momentum (OAM) was demonstrated. And the authors showed that the magnitude of the transverse OAM carried by the ST vortex is scalable to a larger value by simple adjustments.
Abstract: Today, it is well known that light possesses a linear momentum that is along the propagation direction. Besides, scientists also discovered that light can possess an angular momentum, a spin angular momentum (SAM) associated with circular polarization and an orbital angular momentum (OAM) owing to the azimuthally dependent phase. Even though such angular momenta are longitudinal in general, an SAM transverse to the propagation direction has opened up a variety of key applications1. In contrast, investigations of the transverse OAM are rare due to its complex nature. Here, we demonstrate a three-dimensional wave packet that is a spatiotemporal (ST) optical vortex with a controllable purely transverse OAM. Contrary to the transverse SAM, the magnitude of the transverse OAM carried by the ST vortex is scalable to a larger value by simple adjustments. Since the ST vortex carries a controllable OAM uniquely in the transverse dimension, it has strong potential for novel applications that may not be possible otherwise. The scheme reported here can be readily adapted for other spectral regimes and different wave fields, opening opportunities for the study and applications of ST vortices in a wide range of areas. By applying a spiral phase in a pulse shaper, a three-dimensional wave packet, which is a spatiotemporal optical vortex with a controllable purely transverse orbital angular momentum, is demonstrated.

158 citations

Journal ArticleDOI
Andrew C. Strikwerda1, Kebin Fan1, Hu Tao1, D. Pilon1, Xin Zhang1, Richard D. Averitt1 
TL;DR: In this article, the authors have fabricated a quarter-wave plate from a single layer of birefringent electric split-ring resonators (ELC), which achieves 99.9% circular polarization at the design frequency of 639 GHz.
Abstract: We have fabricated a quarter-wave plate from a single layer of birefringent electric split-ring resonators (ELC). For comparison, an appropriately scaled double layer meanderline structure was fabricated. At the design frequency of 639 GHz, the ELC structure achieves 99.9% circular polarization while the meanderline achieves 99.6%. The me-anderline displays a larger bandwidth of operation, attaining over 99% circular polarization from 615 - 743 GHz, while the ELC achieves 99% from 626 - 660 GHz. However, both are broad enough for use with CW sources making ELCs a more attractive choice due to the ease of fabrication. Both samples are free standing with a total thickness of 70 microm for the meanderline structure and a mere 20 microm for the ELC highlighting the large degree of birefringence exhibited with metamaterial structures.

158 citations


Network Information
Related Topics (5)
Scattering
152.3K papers, 3M citations
88% related
Magnetic field
167.5K papers, 2.3M citations
84% related
Spectroscopy
71.3K papers, 1.5M citations
84% related
Dielectric
169.7K papers, 2.7M citations
84% related
Absorption spectroscopy
66.1K papers, 1.4M citations
83% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023384
2022821
2021685
2020927
20191,060
2018968