BALANCING INTERPIXEL CROSS-TALK AND DETECTOR NOISE TO OPTIMIZE AREAL DENSITY IN HOLOGRAPHIC STORAGE-SYSTEMS

We investigate the effects of interpixel cross talk and detector noise on the areal storage density of holographic data storage, A numerical simulation is used to obtain the bit-error rate (BER) as a function o f hologram aperture, pixel fill factors, and additive Gaussian intensi ty noise. We consider the effect of interpixel cross talk at an output pixel from all possible configurations of its 12 closest-neighbor pix els. Experimental verification of this simulation procedure is shown f or several fill-factor combinations. The simulation results show that areal density is maximized when the aperture coincides with the zero o rder of the spatial light modulator (SLM) (Nyquist sampling condition) and the CCD fill factor is large. Additional numerical analysis inclu ding finite SLM contrast and fixed-pattern noise show that, if the fix ed-pattern noise reaches 6% of the mean signal level, the SLM contrast has to be larger than 6:1 to maintain high areal density. We also inv estigate the improvement of areal density when error-prone pixel combi nations are forbidden by using coding schemes. A trade-off between an increase in areal density and the redundancy of a coding scheme that a voids isolated-ON pixels occurs at a code rate of approximately 83%. ( C) 1998 Optical Society of America.