Photochromic effect and spatial light modulation in spiro-oxazine dye-doped polymeric films

A strong reversible photochromic phenomenon in spiro-oxazine (SO) dye-doped polyvinyl alcohol (PVA) films is reported. The absorption spectrum of the SO/PVA film shows an ultra-violet (UV) light induced isormerization process taking place between two molecular configurations, which correspond to the two characteristic absorption bands at 360 nm and 595 nm, respectively. The temporal behavior of this photo-isomerization process is investigated. The molecular absorption coefficients of SO1 to UV light and SO2 to the probe beam at 515 nm are found to be 1.2 cm(2)/J and 6 x 10(-2) cm(2)/J, respectively. The life time of SO2 in the dark is about 38 s. Spatial light modulation and UV-to-visible image conversion using this photochromic film are demonstrated experimentally.