Optical phase conjugation in a nematic liquid-crystal film modulated by a quasi-static electric field

Abstract

A quasi-static field can play an important role in molecular reorientation of the optical nonlinearity in liquid crystals because of the combination of the critical behavior of the sample at the Freedericksz transition and of nonlinear coupling of the optical and quasi-static fields. The nonlinear-optical phenomenon, optical phase conjugation, was observed in an electric-field-biased nematic liquid-crystal film and can be predicted by molecular reorientation calculated with continuum theory. The external field-modulated intensities of the phase-conjugation beams were obtained by both numerical calculation and experimental measurement. At the same time, the rise times of the intensities of phase-conjugation beams were measured for various external fields.

Crucial effects of the anisotropy on optical field induced pattern formation in nematic liquid crystal films

“…We choose the coordinates system with the z axis perpendicular to the cell walls, the x-y plane coincident with the input cell wall and the x direction coincident with the easy axis of the liquid crystal directors. From the continuum theory and by following the derivation of our previous papers [15][16][17], the free-energy density f consisted of the Frank elastic free-energy density, the optical energy density, and the electric energy density is given by:…”

Interference patterns of scattering light induced by orientational fluctuations in an electric-field-biased nematic liquid-crystal film

“…Based on previous research 11,12 the Frank freeenergy density F for an electric-f ield-biased nematic liquid-crystal f ilm is given by…”