Light Confinement with Structured Beams in Gold Nanoparticle Suspensions

We carry out an experimental campaign to investigate the nonlinear self-defocusing propagation of singular light beams with various complex structures of phase and intensity in a colloidal suspension of gold nanoparticles with a plasmonic resonance near the laser wavelength (532nm). Studying optical vortices embedded in Gaussian beams, Bessel vortices and Bessel-cosine (necklace) beams, we gather evidence that while intense vortices turn into two-dimensional dark solitons, all structured wavepackets are able to guide a weak Gaussian probe of different wavelength (632.8 nm) along the dark core. The probe confinement also depends on the topological charge of the singular pump.

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OAM light propagation through tissue

Scientific Reports ◽

10.1038/s41598-021-82033-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Netanel Biton ◽

Judy Kupferman ◽

Shlomi Arnon

Keyword(s):

Light Propagation ◽

Biological Imaging ◽

Gaussian Beams ◽

Medical Implants ◽

Optical Wireless ◽

Scattering Media ◽

Valuable Contribution ◽

Light Beams ◽

First Time ◽

Diffuse Media

AbstractA major challenge in use of the optical spectrum for communication and imaging applications is the scattering of light as it passes through diffuse media. Recent studies indicate that light beams with orbital angular momentum (OAM) can penetrate deeper through diffuse media than simple Gaussian beams. To the best knowledge of the authors, in this paper we describe for the first time an experiment examining transmission of OAM beams through biological tissue with thickness of up to a few centimeters, and for OAM modes reaching up to 20. Our results indicate that OAM beams do indeed show a higher transmittance relative to Gaussian beams, and that the greater the OAM, the higher the transmittance also up to 20, Our results extend measured results to highly multi scattering media and indicate that at 2.6 cm tissue thickness for OAM of order 20, we measure nearly 30% more power in comparison to a Gaussian beam. In addition, we develop a mathematical model describing the improved permeability. This work shows that OAM beams can be a valuable contribution to optical wireless communication (OWC) for medical implants, optical biological imaging, as well as recent innovative applications of medical diagnosis.

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Vortices Nucleation By Inherent Fluctuations In Nematic Liquid Crystal Cells

10.21203/rs.3.rs-859280/v1 ◽

2021 ◽

Author(s):

Esteban Aguilera ◽

Marcel G. Clerc ◽

Valeska Zambra

Keyword(s):

Liquid Crystal ◽

Optical Tweezers ◽

Nematic Liquid Crystal ◽

Topological Defects ◽

Optical Vortices ◽

Topological Features ◽

Nucleation Mechanisms ◽

Multistable Systems ◽

Light Beams ◽

Crystal Cells

Abstract Multistable systems are characterized by exhibiting domain coexistence, where each domain accounts for the different states. In the case of these systems are described by vectorial fields, domains are connected through topological defects. Vortices are one of the most frequent and studied topological defect points. Optical vortices are equally relevant for their fundamental features as beams with topological features and their applications in image processing, telecommunications, optical tweezers, and quantum information. The interaction of light beams with matter vortices in liquid crystal cells is a natural source of optical vortices. The rhythms that govern the emergence of matter vortexes due to fluctuations are not established. Here we investigate the nucleation mechanisms of the matter vortices in liquid crystal cells and establish statistical laws that govern them. Based on a stochastic amplitude equation, the law for the number of nucleated vortices as a function of anisotropy, voltage, and noise level intensity is set. Experimental observations in a nematic liquid crystal cell with homeotropic anchoring and a negative anisotropic dielectric constant under the influence of a transversal electric field show a fair agreement with the theoretical findings.

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