Azocarbazole Polymethacrylates as Single-Component Electrooptic Materials

A series of amorphous azobenzene and carbazole-containing polymers was prepared, which incorporates both electrooptic activity and photoconductivity into a single multifunctional structural unit. The polymers were cast as thin films and were shown to be suitable for photoinducing birefringence reversibly with polarized light, as well as for the inscription of photorefractive diffraction gratings after electric field poling. Since the polymer series encompasses a range of spacer lengths (from 3 to 10 methylene groups) between the multifunctional side chains and the polymer backbone, these materials are suitable for study of the influence of chromophore mobility on these optical phenomena. The extent of orientational order which could be photoinduced in the films was found to decrease with increasing spacer length, as did the photoconductivity and the photorefractive two-beam optical coupling gain. In thin films of polymers with the highest glass transition temperature, a birefringence of 0.065 could be photoinduced, with a time constant of <0.8 s. A two-beam optical gain of 0.024 µm-1 was also demonstrated in films of the polymer with the highest glass transition temperature, although this gain was exceeded by absorption losses.