# Nonlinear continuous-wave optical propagation in nematic liquid crystals: interplay between reorientational and thermal effects

## TL;DR

This paper investigates how reorientational and thermal nonlinearities in nematic liquid crystals influence optical propagation, leading to phenomena like self-focusing and soliton formation, supported by theoretical, numerical, and experimental analyses.

## Contribution

It provides a comprehensive analysis of the interplay between reorientational and thermal effects in nonlinear optical propagation in nematic liquid crystals, combining theory, simulations, and experiments.

## Key findings

- Reorientational and thermal nonlinearities can be tuned to control self-focusing and defocusing.
- Formation of spatial optical solitons depends on the balance between the two nonlinear effects.
- Numerical simulations agree with experimental observations in dye-doped nematic liquid crystals.

## Abstract

Thanks to their unique properties, nematic liquid crystals feature a variety of mechanisms for light-matter interactions. For continuous-wave optical excitations, the two dominant contributions stem from reorientational and thermal nonlinearities. We thoroughly analyze the competing roles of these two nonlinear responses with reference to self-focusing/defocusing and, eventually, the formation of nonlinear diffraction-free wavepackets, the so-called spatial optical solitons. To this extent we refer to dye-doped nematic liquid crystals in planar cells and continuous-wave beams at two distinct wavelengths in order to adjust the relative weights of the two responses. The theoretical analysis is complemented by numerical simulations in the highly nonlocal approximation and compared to experimental results.