Filamentation and Undulation of Self-Focused Laser Beams in Liquid Crystals

Abstract

We describe an experimental and theoretical study of a low-power, continuous-wave laser beam interacting with a nematic liquid crystal. Experimental observations show strong self-focusing, the onset of beam undulation and k e n t a t i o n . A coupled-field model is presented and reduced through a separation of scales perturbation argument. This analysis shows that the light-nematic interaction is very different from conventional self-focusing in Kerr (nonlinear Schrodinger) media, and it provides a new optical setting for the study of the physics of complex nonlinear patterns.

Dissipative solitons

“…1. glass plates; 2. electrically conducting transparent indium tin oxide layers; 3. nematic liquid crystal layer; 4. voltage source; 5. laser producing a polarized beam; 6. camera to record the pattern. After [264][265][266][267][268][269][270]. 556 H.-G. Purwins et al…”

Spatial Solitons in Liquid Crystals

“…Then the mathematical description of the problem consists of the equation (3) without second and third differential components and the Maxwell's equations for the field (5)- (6) in media with electrical permittivity (4). Because of the complexity of the equation system, the solution can be obtained only by using numerical methods.…”

“…Most of the theoretical and experimental works were done for thin samples and only a few papers reported propagation of light beam at lengths longer than the Rayleigh distance. There were experiments showing the self-focusing due to the reorientation process inside liquid crystals in capillaries [4][5][6][7], in planar cells [8], and in planar waveguides [9]. In this article, the main idea leading to create optical solitons due to the reorientation nonlinearity in liquid crystals is presented.…”

Nonlinear TM modes in cylindrical liquid crystal waveguide

“…Several systems for which a nematic is submitted to a large intensity optical field whose configuration is not anchored to waveguide boundary conditions, give rise spatial patterns and solitons [3][4][5]. The basic mechanism which governs these time independent patterns is the balance between the nonlinear refraction (self-focussing) and the spatial diffraction of the nematic.…”