Measurement of the Nonlinear Susceptibility of Liquid Crystal Materials in the Isotropic Phase

Abstract

The nonlinear optical properties of isotropic liquid crystals are characterized using a degenerate four-wave-mixing technique. The role of molecular shape and size is investigated together with the effect of the underlying liquid crystal phases. Magnitudes of nonlinearities are found to be in the range 10 ^m9 to 10 ^m11 esu, dependent on temperature, with reorientation times of 2 to 200 ns, When a mixture of two nematogens is made, anomalous effects are observed in nonlinear behaviour which can be associated with local ordering of the molecules.