Error correction for increasing the usable capacity of photorefractive memories

Conventional error-correction coding techniques can be used to reduce the minimum signal-to-noise ratio required for achievement an acceptable bit-error rate and can therefore be used to increase the maximum number of pages that can be stored in a photorefractive memory. Because error-correction bits will exact some cost per page in terms of memory capacity, we address the question of when the gain in capacity surpasses this cost. It is found that a factor-of-2 improvement in capacity can be readily achieved.