Spiropyran-doped poly(vinyl carbazole): a new photopolymer recording medium for erasable holography

The photosensitive organic system of poly(vinyl carbazole) doped with spiropyran is studied for real-time reversible holography. The photoinduced reversible color change between thermally stable and metastable states of spiropyran molecules can modulate the absorption and the refractive index of the spiropyran-doped polymer film. Erasable holograms can be recorded in either stable or metastable states of such films of thickness 10 and 50 μm prepared by a gravity settling method. The grating constant achieved was δ= 0.58 μm, using the 350-nm UV line of a krypton-ion laser. It has been found that write-read-erase cycles can be performed repeatedly. High-efficiency erasable holographic recording at 350 nm has been performed in these films, and a diffraction efficiency greater than 10% has been achieved.