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Abstract
Picosecond nonlinear absorption and nonlinear refraction were studied for several classes of isotropic phase liquid crystals, including Schiff base and ester compounds. Materials studied exhibit a large two-photon absorption coefficient (j3) at 532 nm.Values of j3 were found to be -0.6 cm/GW in several of the compounds studied. Nonlinear refraction was also observed and the nonlinear refractive index, n2 was measured for each material at 1.06 pm using an external self-focusing mangement. n2 ranged from 6 × 10-13 esu to 2 × 10-l2 esu. The combination of nonlinear absorption and nonlinear refraction in these materials result in optical limiting for input energies as low as 0.15 microjoules for 30 psec pules at 532 nm.