Use of two-photon excitation for erasable–rewritable three-dimensional bit optical data storage in a photorefractive polymer

Abstract

We report what is believed to be the first use of a photorefractive polymer in erasable–rewritable three-dimensional bit optical data storage under two-photon excitation. We successfully demonstrate writing, erasing, and rewriting of multilayered information in a photorefractive polymer consisting of 2,5-dimethyl-4-($p$-nitrophenylazo)anisole, 2,4,7-trinitro-9-fluorenone, 9-ethylcarbazole, and poly($N$-vinylcarbazole). A three-dimensional bit density of $5 \mathrm{Gbits}/{\mathrm{cm}}^3$ is achieved by two-photon absorption under pulsed beam illumination at an infrared wavelength of 800 nm in the recording process. Complete erasing of the recording information is achieved by use of ultraviolet illumination.