Optical Soliton Instabilities and Self-Focusing Control in Highly Non-Local Nematic Liquid Crystals

International Journal of Physics | Vol. 11, No. 10, October 2020 | pp. 73–80

DOI: 10.46882/2020/IJP/000126

Research Article

Title: Optical Soliton Instabilities and Self-Focusing Control in Highly Non-Local Nematic Liquid Crystals

Names of Authors: L. K. Rousseau¹, K. Y. Tanaka²

Authors’ Affiliations:
¹ Laboratoire de Physique des Plasmas, École Polytechnique, Palaiseau, France
² Department of Materials Science, Tokyo Institute of Technology, Tokyo, Japan

Abstract: Managing high-power laser beam propagation profiles and eliminating catastrophic optical filamentation are vital for developing long-range optical links, light-induced waveguides, and compact signal-switching chips. This study models optical soliton instabilities and characterises self-focusing control fields inside nematic liquid crystal cells exhibiting highly non-local thermal reorientational non-linearities. We solved the coupled non-linear Schrödinger and director orientation equations using a variational mathematical approach paired with split-step Fourier numerical simulations. The analytical models establish the exact power thresholds and phase-matching metrics required to launch stable two-dimensional spatial solitary waves. The results prove that increasing the non-local elastic response length from 1.0 mm to 4.5 nm suppresses structural collapse nodes by smoothing localized wavefront phase errors. The modulation instability growth rate was tracked against changing spatial perturbation frequencies, highlighting a maximum gain coefficient of g = 3.18 cm^-1 under an input beam intensity of 2.5 kW/cm². Expanding the non-locality parameter scales down the maximum instability gain by 62.0% and shifts the peak response toward longer modulation wavelengths, effectively avoiding filamentation risks.

Keywords: Nonlinear optics; spatial solitons; nematic liquid crystals; modulation instability; wave collapse; split-step Fourier method

Manuscript Timeline: Received: June 02, 2020; Revised: July 29, 2020; Accepted: August 25, 2020; Published: October 08, 2020

Citation: Rousseau, L. K., & Tanaka, K. Y. (2020). Optical Soliton Instabilities and Self-Focusing Control in Highly Non-Local Nematic Liquid Crystals. International Journal of Physics, 11(10), 73–80.

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