Orbital angular momentum wave generation/detection based on planar multi‐slot‐spiral circularly polarized antenna

2021 ◽  
Author(s):  
Ehsan Koohkan ◽  
Saughar Jarchi ◽  
Ayaz Ghorbani ◽  
Mohammad Bod
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Wave Generation ◽  
Circularly Polarized

scholarly journals Vortex energy flow in the tight focus of a non-vortex field with circular polarization

2020 ◽  
Vol 44 (1) ◽  
pp. 5-11
Author(s):  
V.V. Kotlyar ◽  
S.S. Stafeev ◽  
A.G. Nalimov
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Energy Flow ◽  
Poynting Vector ◽  
Focal Spot ◽  
Free Field ◽  
Longitudinal Component ◽  
Circularly Polarized ◽  
Linearly Polarized ◽  
Direct Energy

Using Richards-Wolf formulas, we show that an axisymmetric circularly polarized vortex-free field can be focused into a sharp subwavelength focal spot, around which there is a region where the light energy flow propagates along a spiral. This effect can be explained by the conversion of the spin angular momentum of the circularly polarized field into the orbital angular momentum near the focus, although the on-axis orbital angular momentum remains zero. It is also shown that a linearly polarized optical vortex with topological charge 2 forms near the focal plane an on-axis reverse energy flow (defined by the negative longitudinal component of the Poynting vector) whose amplitude is comparable with the direct energy flow.

scholarly journals Controllable all-fiber generation/conversion of circularly polarized orbital angular momentum beams using long period fiber gratings

Nanophotonics ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 287-293 ◽  
Author(s):  
Ya Han ◽  
Yan-Ge Liu ◽  
Zhi Wang ◽  
Wei Huang ◽  
Lei Chen ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Higher Order ◽  
Fiber Grating ◽  
Telecommunication System ◽  
Circularly Polarized ◽  
Long Period ◽  
Flexible Mode ◽  
Long Period Fiber Gratings ◽  
Core Modes

AbstractMode-division multiplexing (MDM) is a promising technology for increasing the data-carrying capacity of a single few-mode optical fiber. The flexible mode manipulation would be highly desired in a robust MDM network. Recently, orbital angular momentum (OAM) modes have received wide attention as a new spatial mode basis. In this paper, we firstly proposed a long period fiber grating (LPFG) system to realize mode conversions between the higher order LP core modes in four-mode fiber. Based on the proposed system, we, for the first time, demonstrate the controllable all-fiber generation and conversion of the higher order LP core modes to the first and second order circularly polarized OAM beams with all the combinations of spin and OAM. Therefore, the proposed LPFG system can be potentially used as a controllable higher order OAM beam switch and a physical layer of the translating protocol from the conventional LP modes communication to the OAM modes communication in the future mode carrier telecommunication system and light calculation protocols.

scholarly journals Towards New Chiroptical Transitions Based on Thought Experiments and Hypothesis

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1103
Author(s):  
Takashiro Akitsu ◽  
Sanyobi Kim ◽  
Daisuke Nakane
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Azo Dyes ◽  
Uv Light ◽  
Polarized Light ◽  
Dipole Transition ◽  
Spin Angular Momentum ◽  
Cd Spectra ◽  
Circularly Polarized Light ◽  
Circularly Polarized

We studied supramolecular chirality induced by circularly polarized light. Photoresponsive azopolymers form a helical intermolecular network. Furthermore, studies on photochemical materials using optical vortex light will also attract attention in the future. In contrast to circularly polarized light carrying spin angular momentum, an optical vortex with a spiral wave front and carrying orbital angular momentum may impart torque upon irradiated materials. In this review, we summarize a few examples, and then theoretically and computationally deduce the differences in spin angular momentum and orbital angular momentum depending on molecular orientation not on, but in, polymer films. UV-vis absorption and circular dichroism (CD) spectra are consequences of electric dipole transition and magnetic dipole transition, respectively. However, the basic effect of vortex light is postulated to originate from quadrupole transition. Therefore, we explored the simulated CD spectra of azo dyes with the aid of conventional density functional theory (DFT) calculations and preliminary theoretical discussions of the transition of CD. Either linearly or circularly polarized UV light causes the trans–cis photoisomerization of azo dyes, leading to anisotropic and/or helically organized methyl orange, respectively, which may be detectable by CD spectroscopy after some technical treatments. Our preliminary theoretical results may be useful for future experiments on the irradiation of UV light under vortex.

Design of Cylindrical Conformal Transmitted Metasurface for Orbital Angular Momentum Vortex Wave Generation

2021 ◽  
Author(s):  
Ben Fu ◽  
Shi-Xing Yu ◽  
Na Kou ◽  
Zhao Ding ◽  
Zheng-Ping Zhang
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Wave Generation ◽  
The Way

Abstract In this paper, a cylindrical conformal transmitted metasurface for orbital angular momentum vortex wave generation is proposed. Formulas for calculating the phase distributions of cylindrical conformal transmitted metasurface is presented. A prototype of the proposed conformal transmitted metasurface is designed, fabricated and measured. Measured results shows that the proposed conformal transmitted metasurface can effectively generate vortex waves, which verifies the effectiveness of our method. The proposed method may pave the way for vortex wave generation with cylindrical conformal device.

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