Feedbackless nonlinear holographic associative memories

Several original versions of nonlinearly recorded hologram-based associative memories are summarized. All of them are realized using phase-conjugate properties of such holograms being associated just with nonlinear part of a holographic recoding. The photorefractive prototypes of some represented memories are pointed out. The introduced all-optical associative memories exhibit error-correcting properties, ability to edge enhancement into associative responses, and may by realized at arbitrary recording media (thin or volume, permanent or reversable).