an interferometric optical switching device for switching substantially coherent light beams includes a plurality of interferometric switching cells arranged in matrix form . each interferometric switching cell is independently controllable to selectively direct received light beams along at least a selected one of two axes . the device can be three - dimensionally expanded to increase the number of ports to which the light beams can be selectively switched , in which case the matrices can share integrally constructed interferometric switching cells . the device is further capable of providing bidirectional communication between predetermined ones of the ports thereof .