Abstract

In order for holographic storage to meet the needs of future high-performance storage applications, a reliable method for non-destructive readout of digital data must be demonstrated. One promising technique is thermal fixing by mobile ion comensation in photorefractive media such as LiNbO₃ and BaTiO₃-Thermal fixing of 500 image-bearing holograms in Fe-doped LiNbO₃ has been demonstrated in the past[1]. This demonstration utilized the transmission geometry. Recording was done at elevated temperature and the stored information consisted of simple images rather than digital data. For data storage applications, it is desirable to work in the perpendicular recording geometry so that noise caused by scatter of the reference beam is minimized. In addition, the perpendicular geometry affords the greatest angular sensitivity, allowing the possibility of multiplexing thousands of pages in one location. We demonstrate a holographic storage system that incorporates in situ thermal fixing in the perpendicular geometry. Fixing is accomplished using a post-recording heating procedure. Recording and readout both occur at room temperature to avoid thermal effects that lead to incomplete Bragg matching. This system is a true digital storage device in which we have measured the effects of the fixing process on the bit-error-rate (BER) of the system.

© 1996 Optical Society of America