Characterization of the dye-doped polymer films as recording materials

By means of real-time holographic recording, two important classes of photochromic compounds (spiropyrans and fulgides) have been characterized. For spiropyran molecules, important thickness and writing intensity effects were observed. Concerning fulgides molecules, photochemical fatigue resistance in different polymer hosts was investigated. After 10 irradiation cycles, the closed form lost 9, 11, 13 and 35% of its initial absorbance respectively in PS, CA, PMMA and PVK. For the holographic study, diffraction efficiency in fulgide doped PMMA films was strongly dependent on the writing intensity: the rise time tau takes values 25 and 7s for respectively 2 and 8 mW/cm(2). Optimum fulgide concentration and writing exposure have been obtained: diffraction efficiency is maximum with a concentration of 2% and an intensity of 4mW/cm(2).