NEW NONLINEAR-OPTICAL MATERIALS FROM LIVING MATTER

There is current interest in organic materials for use in opto-electro nics. The dielectric properties of these materials have proved compati ble with low biasing powers, and some methods to improve them have bee n proposed. We discuss some fatty acids and mixtures of fatty acids, a s well as fatty acid-cholesterol, all of them having an important role in biological membranes. They have smectic liquid-crystalline propert ies in some temperature ranges, this state being involved in the mecha nisms determining health and illness. They can be used also in optoele ctronic applications, because of the huge optical nonlinearity in the mesomorphic domain. The external self-focusing of a laser beam and non linear optical activity have been observed experimentally; by studying the modification of laser pulses in such media, the cholesterol perce ntage could be estimated. Also the interaction, at different wavelengt hs, with coherent and noncoherent light was studied. (C) 1996 Society of Photo-Optical Instrumentation Engineers.