Optical crossbar elements used for switching networks

An optical crossbar element that uses birefringent crystal plates and programmable half-wave plates is proposed. It is compact, cascadable, and well suited for realizing an array of switching elements employed in multistage interconnection networks. Arrays of two-input/two-output and four-input/fourputput crossbar switching elements and a Clos (4, 4, 4) network are also presented.