LIGHT-INDUCED 2ND-HARMONIC GENERATION IN AZO-DYE POLYMERS

The permanent all-optical poling of an azo-aromatic acrylic copolymer is experimentally demonstrated by seeding preparation in a backward ph ase-conjugation geometry. The microscopic mechanism involves an orient ational hole burning followed by orientational redistribution caused b y trans-to-cis isomerization of the azo-dye chromophores. The characte ristic kinetics of growth and decay of the noncentrosymmetry grating i s monitored by second-harmonic generation.