Abstract

An N × N optical space switch is described which uses holographic associative memory techniques to store switch states. The switch states are stored as follows: Light from one input port is spatially expanded and then phase-front encoded by a spatial light modulator and directed onto a phase volume holographic recording material. Light corresponding to the available output ports is allowed to fall, in turn, to the same region of the holographic medium. By using a unique phase-front code on the input (reference) wave as it is stored in association with each output (object) wave, a multiplexed phase volume hologram with associative recall properties is created. This process is repeated for all N input ports. Crosstalk can be minimized and efficiency maximized by selecting a suitable orthogonal set of reference wave codes and by maximizing the angular separation between the object point sources so that the Bragg extinction angle is exceeded. The main advantage of this type of optical switching system is that all switch states are preprogrammed and may be tailored to particular needs.

© 1987 Optical Society of America