Photoinduced optical anisotropy in azo-dye doped polyimide films

Using a two-wave mixing technique supplemented by the illumination of the second laser, we studied the dynamics of the photoinduced anisotropy in polyimide free-standing films doped by azo-dyes containing one or two N=N bonds. We have measured the characteristics of grating recording using a He-Ne laser source (λ = 632.8 nm) under influence of light coming from a cw YAG laser doubled in frequency (λ = 532 nm). The experiments in polyimide-Disperse Red 1 (4-[N-ethyl-N-(2-hydroxyethyl)]amino-4'-nitro-azobenzene) system revealed complex kinetics of photoinduced birefringence leading to grating recording and light self-diffraction. The two main processes were identified during the grating build-up in this high T g polymer matrix. Preliminary results on possibility of dynamic color and polarization holographic recording in polyimide containing newly synthesized molecule having two N=N bonds 1,3 diamino-4-azo(4'-nitroazobenzene)benzene are also presented.