Thermal dependence of the lateral shift of a light beam reflected from a liquid crystal cell deposited on a magnetic film

Abstract

We study the influence of the thermo-optic effect and of thermal expansion on the lateral shift experienced by a Gaussian near-infrared beam upon reflection from a voltage-controlled nematic liquid crystal cell deposited on a magnetic yttrium-iron garnet film. Variations of temperature are considered in the range between room temperature and the nematic-isotropic phase transition temperature of the liquid crystal and induce changes in both the layer thicknesses and the permittivity tensor components of the constituents. We show that for all polarization configurations of the incoming and reflected beams, these changes modify the amplitude of the extrema of the lateral beam shift and their position with respect to the incidence angle of the beam and, except in the s–s polarization configuration, to the voltage applied to the liquid crystal cell. In the p–p and p–s polarization configurations, this drift can thus be controlled at some incidence angles by tuning the applied voltage. Moreover, in the p–s configuration, the lateral shift can be also controlled by a magnetization reversal in the magnetic layer. Finally, we discuss the possibility of temperature monitoring using the temperature dependence of the lateral shift in this system.