Theory and experimental studies of all-optical transmission switching in a twist-alignment dye-doped nematic liquid crystal

We present a theoretical model and experimental demonstration of an all-optical switching process occurring in twist alignment dye-doped nematic liquid crystal cells. A Landau-deGennes theory is applied together with the thermal buildup and diffusion equation to analyze the laser-induced temperature, the order parameter, and the birefringence changes in the liquid crystal cell. The resulting transmission switching processes are calculated using a modified Jones matrix method. Experimental observations of the switching processes in cells of varying thicknesses and their dependence on the input optical power are in good agreement with theoretical predictions. We have also studied the dynamics of the switching processes and observed microseconds switching times. These studies demonstrate the possibility of low-threshold power and microseconds speed switching applications. (C) 2008 Optical Society of America