Azobenzene-containing polymers have attracted much attention as photo-responsive materials owing to potentialapplications in optical data storage and holographic recording. In holography, azobenzene compounds doped in apolymer matrix (guest- host polymer film) or chemically attached to the polymer (co-polymer) are among the mostwidely used materials. Azo-polymers exhibit differing behaviors when exposed to a pattern resulting from theinterference of two coherent beams. In the guest-host system, the recorded grating corresponds to a contrast of refractiveindex between the dark and bright areas of the film, and in the co-polymer, interference patterns lead to surface heightmodulation; i.e. surface relief gratings (SRGs). The latter is due to photo-induced mass movement of the polymer frombright to the dark area of the interference pattern in the direction of the intensity gradient, and the photoisomerizationforce is at the origin of the formation of the gratings. In this paper, we give an overview of our experiments onholographic recording in both guest host and co-polymers systems; e.g. doped and covalently attached polymers, andbased on the theory of photo-induced vectorial mobility of matter, we discuss the results obtained for the co-polymersystem.
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