CROSS-ERASURE NOISE IN HIGH-DENSITY HOLOGRAPHIC-STORAGE SYSTEMS

We consider a process by which images recorded in high-density hologra phic storage systems may be degraded. In particular, the recording of many holograms in the same volume results in cross erasure of each hol ogram by the sum of all the remaining holograms superposed in the same volume. This effect is, in general, spatially nonuniform and varies b oth transversely across each recorded image and in depth as the image propagates and diffracts throughout the volume of the recording medium . We apply a three-dimensional numerical analysis to assess the bit er ror rate (BER) resulting from this noise source as a function of vario us recording parameters. In particular, Re use this analysis to determ ine the optimum exposure schedule for a given BER. We then describe me ans by which these noise sources can be largely circumvented through a ppropriate choice of the writing-beam intensities or the recording geo metry or the use of random-phase screens. (C) 1997 Optical Society of America.