Operator formalism for optical neural network based on the parametrical   four-wave mixing process
  In this paper we develop a formalism allowing us to describe operating of a network based on the parametrical four-wave mixing process that is well-known in nonlinear optics. The recognition power of a network using parametric neurons operating with q different frequencies is considered. It is shown that the storage capacity of such a network is higher compared with the Potts-glass models. 
L. B. Litinskii, B. V. Kryzhanovsky, and A. Fonarev
cs.ET cond-mat.dis-nn