Abstract

Recently, it has been, shown that liquid crystals possess a variety of nonlinear optical mechanisms existing over a large range of time scales from ps to ms.^1,2 Of particular interest are those based on thermal, orientational, and density excitations, which exist even in isotropic phase and exhibit rise times of a few to tens of nanoseconds. Here, we demonstrate how these nonlinearities can be exploited to construct a fast optical limiting device with threshold energy fluences of µJ/cm² and lower. An interesting multiple- limiting behavior has also been observed, the origin of which is traced to the multiple nonlinearities of liquid crystals induced by the laser pulse.

© 1993 Optical Society of America