PHOTOINDUCED NONLINEAR EFFECTS IN ORGANIC PHOTOCHROMICS

Abstract

An analytic expression describing two-wavelength light propagation through an organic photoreversible photochromic Azo and Stilbene-like molecular media characterized by a strong nonoverlapping absorption by the two chromophore isomers has been derived. An analysis of the transmission coefficients for the Trans and Cis modulation modes has shown linear dependence on the pump intensity accompanied by self modulation slope dependence. In addition, the wavelength dependence of the modulation strength and the resulting inverse relationship of the pump intensity as a function of the absorption cross-section has been presented. Large constrast ratios have been obtained for rather low pump and read-out intensities of the order of a hundred microwatts per centimeter square and less. Such optimal working conditions provide a very attractive characteristic for an OASLM based on photoreversible photochromic organic molecular systems.