CREATION OF SECOND-ORDER NONLINEAR-OPTICAL EFFECTS BY PHOTOISOMERIZATION OF POLAR AZO DYES IN POLYMERIC FILMS - THEORETICAL-STUDY OF STEADY-STATE AND TRANSIENT PROPERTIES

It was shown recently that the application of a dc field across a polymer film containing polar azo dye chromophores at a temperature far below that of its glass transition leads to an appreciable polar order when the azo dyes undergo cis double left right arrow trans isomerization. We present a detailed theoretical study of this phenomenon based on the enhanced mobility of the azo chromophores during the isomerization process. The equations representing this phenomenological theory are solved by recurrence relations of Legendre polynomials, and both the steady state and the dynamics are investigated. Analytical expressions are derived for the photoinduced polar order and its related anisotropy for both cis and trans molecular distributions.