NONLINEAR-OPTICAL PROPAGATION AND SELF-LIMITING EFFECT IN LIQUID-CRYSTALLINE FIBERS

The nonlinear optical properties of the isotropic phase of liquid crystals induced by nanosecond laser pulses are analyzed in the context of nonlinear multimode propagation in a liquid-crystal-cored fiber. The negative thermal density nonlinearity of the core gives rise to an intensity-dependent loss in the core-guided transmission and optical action. Experiments conducted with such liquid-crystal-cored fibers show that the optical limiting threshold for nanosecond laser pulses can be as low as 0.09 J/cm2, which is one of the lowest among known nonlinear optical materials and structures, including bulk liquid-crystal films.