The Propagation of Vortex Beams in Random Mediums

Mapping Intimacies ◽

10.5772/intechopen.101061 ◽

2021 ◽

Author(s):

Sekip Dalgac ◽

Kholoud Elmabruk

Keyword(s):

Angular Momentum ◽

Orbital Angular Momentum ◽

Optical Communications ◽

System Performance ◽

Topological Charge ◽

Dark Spot ◽

High Dimensional ◽

Free Space Optical ◽

Phase Singularity ◽

Vortex Beams

Vortex beams acquire increasing attention due to their unique properties. These beams have an annular spatial profile with a dark spot at the center, the so-called phase singularity. This singularity defines the helical phase structure which is related to the topological charge value. Topological charge value allows vortex beams to carry orbital angular momentum. The existence of orbital angular momentum offers a large capacity and high dimensional information processing which make vortex beams very attractive for free-space optical communications. Besides that, these beams are well capable of reducing turbulence-induced scintillation which leads to better system performance. This chapter introduces the research conducted up to date either theoretically or experimentally regarding vortex beam irradiance, scintillation, and other properties while propagating in turbulent mediums.

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High-dimensional free-space optical communications based on orbital angular momentum coding

Optics Communications ◽

10.1016/j.optcom.2017.10.035 ◽

2018 ◽

Vol 410 ◽

pp. 333-337 ◽

Cited By ~ 3

Author(s):

Li Zou ◽

Xiaofan Gu ◽

Le Wang

Keyword(s):

Angular Momentum ◽

Orbital Angular Momentum ◽

Optical Communications ◽

Free Space ◽

High Dimensional ◽

Free Space Optical

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High-Efficiency Spin-Related Vortex Metalenses

Nanomaterials ◽

10.3390/nano11061485 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1485

Author(s):

Wei Wang ◽

Ruikang Zhao ◽

Shilong Chang ◽

Jing Li ◽

Yan Shi ◽

...

Keyword(s):

Angular Momentum ◽

Orbital Angular Momentum ◽

Topological Charge ◽

High Efficiency ◽

Infrared Band ◽

Mid Infrared ◽

Integrated Devices ◽

Vortex Beams ◽

Topological Charges

In this paper, one spin-selected vortex metalens composed of silicon nanobricks is designed and numerically investigated at the mid-infrared band, which can produce vortex beams with different topological charges and achieve different spin lights simultaneously. Another type of spin-independent vortex metalens is also designed, which can focus the vortex beams with the same topological charge at the same position for different spin lights, respectively. Both of the two vortex metalenses can achieve high-efficiency focusing for different spin lights. In addition, the spin-to-orbital angular momentum conversion through the vortex metalens is also discussed in detail. Our work facilitates the establishment of high-efficiency spin-related integrated devices, which is significant for the development of vortex optics and spin optics.

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Sectorial perturbation of vortex beams: Shannon entropy, orbital angular momentum and topological charge

Computer Optics ◽

10.18287/2412-6179-2019-43-5-723-734 ◽

2019 ◽

Vol 43 (5) ◽

pp. 723-734 ◽

Cited By ~ 6

Author(s):

A.V. Volyar ◽

M.V. Bretsko ◽

Ya.E. Akimova ◽

Yu.A. Egorov ◽

V.V. Milyukov

Keyword(s):

Angular Momentum ◽

Orbital Angular Momentum ◽

Shannon Entropy ◽

Topological Charge ◽

External Perturbation ◽

Informational Entropy ◽

Large Perturbation ◽

Wide Range ◽

Vortex Beams ◽

Computing Measuring

Transformations of the vortex beams structure subjected to sectorial perturbation were theoretically and experimentally studied. The analysis was based on computing (measuring) the vortex spectrum that enables us to find the orbital angular momentum (OAM) and Shannon entropy (informational entropy). We have revealed that, in the general case, the number of vortices caused by an external perturbation is not related to the topological charge. For arbitrary perturbation, the topological charge remains equal to the initial topological charge of the unperturbed vortex beam. Growth of the vortex number induced by perturbations is associated with the optical uncertainty principle between the sectorial angle and the OAM. The computer simulation has shown that OAM does not depend on the number of vortices induced by perturbations. Moreover, two maxima are formed both in the positive and negative regions of the vortex spectrum. As a result, the OAM does not practically change in a wide range of perturbation angles from 0 to 90 °. However, at large perturbation angles, when the energy is almost equally redistributed between the vortex modes with opposite signs of the topological charge, the OAM rapidly decreases. At the same time, the Shannon entropy monotonically increases with growing perturbation angle. This is due to the fact that the entropy depends only on the number of vortex states caused by external perturbations.

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Detecting the topological charge of a vortex beam by an arc slit diffraction

International Journal of Modern Physics B ◽

10.1142/s0217979217501727 ◽

2017 ◽

Vol 31 (23) ◽

pp. 1750172 ◽

Cited By ~ 2

Author(s):

Dongzhi Fu ◽

Hailong Zhou ◽

Kaiwei Wang ◽

Pei Zhang ◽

Jianji Dong ◽

...

Keyword(s):

Angular Momentum ◽

Diffraction Pattern ◽

Orbital Angular Momentum ◽

Topological Charge ◽

Light Spot ◽

Far Field ◽

Vortex Beam ◽

Efficient Measurement ◽

Vortex Beams

The simple and efficient measurement of the light orbital angular momentum (OAM) is essential to both the classical and quantum applications with vortex beams. Here, we study the diffraction pattern in the far field when a vortex beam passes through an arc slit and demonstrate experimentally that a light spot of the diffraction pattern has a displacement which is linear to the topological charge (TC) of the incident vortex beam. Based on this property, this method is capable of measuring both modulus and sign of TC of the vortex beam. Furthermore, this scheme allows identifying multiple OAM states simultaneously.

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