Nonlinear optical molecular properties associated with cis-trans photochromic transformation

In this paper, we examine the nonlinear optical properties of molecular systems undergoing cis-trans photoisomerization process. Such a process gives rise to dynamic photochromism on a picosecond time scale. A kinetic analysis of a general cis-trans nonlinear organic absorber is performed. The analysis is used to derive an expression for the complex nonlinear-molecular index of refraction. The properties of a molecular SLM based on such an absorber are discussed by examining the azo type molecular system. These calculations predict an optimum contrast ratio and fast on-off switching for the SLM performance, achieved at low read-write laser intensities.