Using modulation theory, we develop a simple ((2 + 1) dimensional) model to describe the synergy between the thermo-optical and reorientational responses of nematic liquid crystals to light beams in order to describe the routing of spatial optical solitary waves-nematicons-in such a uniaxial environment. Introducing several approximations based on the nonlocal physics of the material, we are able to predict the trajectories of nematicons and their angular steering with temperature, accounting for the energy exchange between the input beam and the medium through one photon absorption. The theoretical results are then compared with experimental data from previous studies, showing excellent agreement.

The propagation of light induced thermo-reorientational solitary waves in nematic liquid crystals is studied using numerical solutions of the full governing equations and variational approximations. These thermo-reorientational solitary waves form as the nonlocal refractive index response to extraordinarily polarized light beams is both self-focusing via the induced rotation of the constituent molecules and self-defocusing owing to the temperature increase through optical absorption. These competing nonlinearities can lead to the formation of one-and two-dimensional multi-humped solitary and ring-shaped waves at high enough optical powers, with a volcano profile in the plane transverse to propagation. The variational solutions for these self-localized structured beams are in remarkably good agreement with full numerical solutions of the governing equations.