Abstract

In optical neural networks, interconnection of two-dimensional planes of neurons is facilitated by the large storage capacity and high Bragg selectivity of volume phase holograms. In spite of the high Bragg selectivity, cross talk due to the conical Bragg degeneracy remains an issue. In a recent paper, Owechko and Soffer¹ proposed using the spatially and angularly multiplexed holograms in a self-pumped phase conjugate mirror (SPPCM) at the Fourier plane to provide the global inter-connection and to reduce the holographic cross talk between planes of neurons. In this paper, we describe experimental evidence and give physical explanation of the drastic difference in cross talk (in optical interconnection using SPPCM at the Fourier plane) with respect to points along the horizontal versus those along the vertical directions. We show that the removal of Bragg degeneracy applies only in the horizontal but not in the vertical direction. The observation and explanation reveal that similar anisotropic behavior can be expected in other parameters as well under rather broad conditions.

© 1992 Optical Society of America