An examination of the optical dielectric tensor of a liquid crystal waveguide

Abstract

Abstract A sensitive method for the determination of the optical dielectric tensor configuration of thin aligned FLC layers is presented. S(TE) and p(TM) polarised light at 632.8nm is prism-coupled into leaky Fabry-Perot modes when the incident photon momentum along the layer matches a particular guided mode momentum. The reflectivity is monitored as a function of the angle of incidence whereby sharp dips in the reflected intensity are recorded. Computer modelling of Fresnel's equations for general biaxial multilayer media using a Scattering Matrix method is compared to data from which detailed information about the liquid crystal refractive index tensor may be obtained. From data modelled in theS * C phase, we show that there is no out-of-plane tilt, but that the in-plane tilt profile of the director configuration is consistent with the chevron formation of the smectic layers observed in X-ray scattering work.