Accurate measurement of spatial distributions of laser-induced refractive index change in liquid crystal by means of optical interferometer

Abstract

Spatial distributions of laser-induced refractive index change in liquid crystals were observed by means of a Mach-Zehnder interferometer with high accuracy. The pump laser beam with a Gaussian profile was absorbed in dye-doped liquid crystal and the refractive index was changed due to the photothermal effect. The observed distributions of refractive index change were in good agreement with the Gaussian profile and the value of refractive index change was proportional to the pump beam intensity. Since the generated heat diffuse according to the heat conduction equation, the e^<-2> diameter of refractive index change distribution was slightly larger than that of the pump beam intensity distribution.