Dyed gelatin film as a storage material for volume phase holograms

Abstract

Dye-sensitized gelatin is a common recording material for volume holograms. The dye acts as a spectral sensitizer in light-sensitive materials such as silver halide, dichromated gelatin, and photopolymers, mostly used as volume phase recording media. The dye, however, can be used in a pure gelatin matrix also for real-time experiments, e.g., degenerate four-wave mixing facilitated by the cis-trans isomerization of the dye to record polarization-sensitive gratings. This paper describes some preliminary results concerning an observed photoinduced crosslinking effect of a dyed gelatin. The system comprises a halogenated xanthene dye, Eosin Y in a gelatin matrix, an electron donor (triethanolamine) and hydrogen-hexachloroplatinate (IV), a prehardening agent. Experiments have shown that this photochemical reaction—a photooxidation process—constitutes a system with the capability of recording volume phase holograms. As the selection of dyes with photooxidizing properties is vast in terms of spectral sensitivity such a system could in theory be tailored to any laser wavelength in the visible and possibly near-infrared.