FLUCTUATIONS AND LIGHT-SCATTERING IN A LIQUID-CRYSTAL POLYMER FIBER

The spatial correlation function is calculated for thermal fluctuation s of the liquid crystal director field in the core of an optical fiber composed of a main chain Liquid crystal polymer in the smectic-C phas e. Due to steric constraints on the liquid crystal polymer, the smecti c layers orient perpendicular to the fiber axis, the liquid crystal di rector Lies flat against the core-cladding interface, and a line discl ination appears along the fiber axis. The analysis is based on a Landa u-de Gennes expression for free energy, which includes ordinary smecti c-C elastic terms as well as terms added to model the disclination. Th e correlation function is used to relate the scattering distribution a nd attenuation of guided light to the elastic constants of the Liquid crystal polymer.