Patent ID: 6172778
Filing Date: 2001-01-09
Classification: G02B,G02F

Abstract:
A planar optical crossbar switch, comprising:first (10) and second (30) light transmissive substrates, through which light propagates by means of internal reflection;a one dimensional array of light sources (14), disposed on said first substrate;a one dimensional array of detectors (36), disposed on said second substrate;a first holographic element (12) disposed on said first substrate, which diffracts a light signal from at least one of said light sources into a first substantially cylindrical diverging wave (18) which is trapped and propagates inside said first substrate;a second holographic element (20) disposed on said first substrate, laterally of said first holographic element, which diffracts said first substantially cylindrical wave into a substantially plane wave (22) which emerges from said first substrate;a two dimensional spatial light modulator (38) comprising rows and columns of elements, which directs said substantially plane wave emerging from said first substrate in accordance with the status of said spatial light modulator, said spatial light modulator being disposed opposite said second holographic element;a third holographic elements (32) disposed on said second substrate opposite said spatial light modulator, such that it diffracts said substantially plane wave directed by said spatial light modulator into said second substrate as a second substantially cylindrical converging wave which is trapped and propagates inside said second substrate; anda fourth holographic element (34) disposed on said second substrate, laterally of said third holographic element, which diffracts said second substantially cylindrical wave into a substantially plane wave which emerges from said second substrate into at least one of said detectors (36).