Nonlinear Optical Neural Networks: Dynamic Ring Oscillators

We analyze the dynamics of a simple nonlinear optical circuit and draw upon analogies with neural network models. A key element in the circuit is a dynamic holographic medium, a photorefractive medium, which serves as a long-term memory. We discuss associative recall with the device in the context of competition among the memory states of the system. When the system is not being addressed, it will forget in time the stored items. At the same time, the system can display an unlearning phenomenon whereby long-term memory traces tend to equalize their strengths. Under other conditions the system will become obsessive, forgetting all memory traces except for one.