Digital holographic data storage in a high-performance photorefractive polymer composite

Binary information in the form of a 256 × 256 pixel array has been stored holographically within a polymeric photorefractive composite of 130-nm thickness. Devices used consisted of 55-wt. % organic chromophore 1-(2′-ethylhexyloxy)-2,5-dimethyl-4-(4″nitrophenylazo) benzene and up to 11.2-wt. % 2,4,7-trinitro-9-fluorenone (TNF) dispersed within a poly(N-vinyl carbazole) matrix. In a degenerate four-wave mixing arrangement, the refractive-index modulation and speed were 10-3 and 200 ms, respectively. The high TNF concentration leads to short digital hologram recording times of 2 s without detriment in optical quality. Although not yet optimized, a figure of merit, M#, for holographic storage in this composite has been measured to be 0.017, and this is estimated to reach 0.18 in a revised experimental geometry. © 2001 Optical Society of America.