HOLOGRAPHIC AND SPECTROSCOPIC CHARACTERIZATION OF SPIROPYRAN DOPED POLY(METHYL METHACRYLATE) FILMS

Photo-induced reversible color change between thermally stable and metastable states of spiropyran molecules can modulate the absorption and refractive index of spiropyran doped polymer films. Thus erasable holograms can be recorded in either stable or metastable states of the spiropyran doped polymer films. Commercially available spiropyran was doped in poly(methyl methacrylate) and thick and thin polymer films were prepared by the gravity settling method. It was found that write and erase cycles can be performed repeatedly. High efficiency erasable holographic recording at either 350 nm or 647 nm was performed in the spiropyran doped poly(methyl methacrylate) films, and a maximum diffraction efficiency about 6% was achieved.