Experimental observation of nonlinear beam splitting in dye-doped liquid crystal waveguides

Liquid crystals have effective nonlinear optical coefficients that are orde rs of magnitude larger than other materials exploited in integrated optics. The addition of some organic dyes in small amounts may further enhance the nonlinear optical response and even change its sign. We used a dye-nematic liquid crystal mixture exhibiting a negative optical nonlinearity. We obse rved the nonlinear spatial splitting of the guided modes in a symmetric pla nar waveguide whose core was the liquid crystal mixture. This nonlinear eff ect has been observed with very low laser power input and the power thresho ld dependence on dye concentration and core thickness was investigated.