Ortho-nitrostilbenes in polycarbonate for holographic data storage

Holographic data storage materials based on dye-doped polycarbonate that could find application in professional archival and consumer applications are described. The dyes are selected from the class of o-nitrostilbenes, which irreversibly bleach under exposure to light and show high thermal stability before and after exposure. The reduction in concentration of the dye in the host after exposure induces refractive index variations over a wide range of wavelengths and extends well away from the dye absorption peak conforming to the Kramers-Kronig relationship. The materials are injection moldable into the standard disc format and have negligible shrinkage during data storage. Samples were produced using different dyes and various concentrations in a polycarbonate host and processed on professional CD/DVD equipment. The refractive index change is as high as 0.04, with a measured instantaneous sensitivity of 0.5 cm J(-1) and M/# = 0.3.