The Propagation of Vortex Beams in Random Mediums

Abstract

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.

Orbital Angular Momentum Wave Generation and Multiplexing: Experiments and Analysis Using Classical and Quantum Optics

“…High-order HGM lasing and another higher-order HGM lasing are easily achieved. Generations of helically phased beams HG01 and HG10 are combined to give optical vertices [45]. Fundamental Gaussian mode can be converted to helically phased mode using laser.…”

“…A telescope is also used to transform Hermite-Gaussian (HG) and LG modes. π converters and π/2 converters, which are also called λ/4 and λ/2 plates [45], are used to transform HG to LG modes. These optical devices have many more advantages over holograms.…”

“…The oceanic turbulence Geometric Gaussian (HGG) vortex beam is also analyzed with different wavelengths [45]. In underwater optical communication (UOC), HG are separated as Gaussian mode, modified exponential Gaussian mode, modified LG mode, and modified Bessel's mode [47].…”

“…In a random medium such as the atmosphere, ocean, and tissue, optical beam intensity fluctuates in the propagation paths [45]. Scintillation is caused by temperature variations in the random medium, which results in index-of-refraction fluctuations.…”

“…In oceanic communication spatial correlations, Kolmogorov power spectrum is a method used to analyze the atmospheric effect [45]. Backward scattering method is also used for OAM analysis in turbulent atmosphere [61].…”