Topic
Circular polarization
About: Circular polarization is a research topic. Over the lifetime, 15201 publications have been published within this topic receiving 234418 citations.
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TL;DR: This work introduces chiral antenna parameters: the chirality flux efficiency and the chiral antennas aperture, which quantify the generation and dissipation of chiral light and paves the way toward broadly tunable chiral optical applications including ultrasensitive detection of molecular chirability or optical information storage and transfer.
Abstract: Chiral metallic nanostructures can generate evanescent fields which are more highly twisted than circularly polarized light. However, it remains unclear how best to exploit this phenomenon, hindering the optimal utilization of chiral electromagnetic fields. Here, inspired by optical antenna theory, we address this challenge by introducing chiral antenna parameters: the chirality flux efficiency and the chiral antenna aperture. These quantities, which are based on chirality conservation, quantify the generation and dissipation of chiral light. We then present a label-free experimental technique, chirality flux spectroscopy, which measures the chirality flux efficiency, providing valuable information on chiral near fields in the far field. This principle is verified theoretically and experimentally with two-dimensionally chiral coupled nanorod antennas, for which we show that chiral near and far fields are linearly dependent on the magnetoelectric polarizability. This elementary system confirms our concept ...
73 citations
TL;DR: In this paper, a dual circularly polarized antenna is proposed by etching cross slots on the patch, and the patch is fed by two L-strips which provide wide impedance bandwidth and high isolation level.
Abstract: A novel design of dual circularly polarized antenna is proposed. By etching cross slots on the patch, circular polarization (CP) is achieved. The patch is fed by two L-strips which provide wide impedance bandwidth and high isolation level. Polarization diversity between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) is provided by switching the two ports and both LHCP and RHCP signals can be received simultaneously. The experimental results show that the 3 dB axial ratio CP bandwidth of the proposed design is increased two times, as compared to a referential CP antenna fed by L-strip. The details of experimental results for the proposed design are presented and discussed.
73 citations
TL;DR: This paper proposes a scheme to design switchable quarter-wave plate for terahertz wave that is composed of graphene based grating and metallic grating structures that can dynamically switch the transmission wave among left-handed, right-handed circular polarization and linear polarization states.
Abstract: Graphene is a good candidate material in designing tunable terahertz devices due to its tunability of sheet conductivity. In this paper, we propose a scheme to design switchable quarter-wave plate for terahertz wave that is composed of graphene based grating and metallic grating structures. The proposed active device can dynamically switch the transmission wave among left-handed, right-handed circular polarization and linear polarization states by electrically controlling the Fermi energy of the graphene grating. The device is analyzed with grating circular polarizer theory and its performance is investigated through full wave simulations on practically realizable geometry. The proposed quarter-wave plate having a subwavelength thickness demonstrates a wide angle of incidence tolerance, and a broad bandwidth operation. This device concept offers a further step in developing tunable polarizers and polarization switchers, which may be applied in practical terahertz image and communication systems.
73 citations
TL;DR: In this article, a bi-layer ultrathin anisotropic metasurface was proposed to convert the circular-polarized electromagnetic wave to its cross polarization. But, the resonance frequency of the metamodel was not optimized.
Abstract: We demonstrate a bi-layer ultrathin anisotropic metasurface which could near-completely convert the circular-polarized electromagnetic wave to its cross polarization. The bi-layer metasurface is composed of periodic 180°-twisted double-cut split ring resonators on both sides of an F4B substrate. At resonance, cross-polarized transmission larger than 94% is observed both in simulations and experiments. The resonant frequency of the metasurface could be effectively tuned by adjusting the geometric parameters of the metasurface, while relatively high conversion efficiency is preserved. The high efficiency and ease of fabrication suggest that the ultrathin metasurface could have potential applications in telecommunications.
73 citations
TL;DR: In this paper, a general discussion of the induction of optical activity by circularly polarized light is presented and three different mechanisms, or their combinations, can cause asymmetric induction, and particular attention is paid to the asymmetric synthesis of helicenes.
Abstract: The reactions induced by circularly polarized light are reviewed and a general discussion of the induction of optical activity by circularly polarized light is presented. It is concluded that three different mechanisms, or their combinations, can cause asymmetric induction. In each case the optical yield is dependent on the optical anisotropy factor g, the ratio between the circular dichroism (Δϵ) and the extinction coefficient (ϵ). The results are discussed in terms of the presumed mechanisms, and particular attention is paid to the asymmetric synthesis of helicenes. It is concluded that this kind of photochemistry may have analytical importance.
73 citations