Design of optical multi/demultiplexers composed of bidirectional 2 × 2 switch elements for reducing component count

A component-efficient design for optical multi/demultiplexers (OMDPXs) relying on 2 × 2 switch elements (SEs) with a bidirectional property is described for the first time. First, the observation is made that some 2 × 1 or 1 × 2 SEs used in conventional OMDPXs have been implemented with part of a 2 × 2 SE. A novel design of OMDPXs fully utilising the connection capability of 2 × 2 SEs is presented. The SE count in the design becomes virtually half of that in the conventional design because a 2 × 2 SE is equivalent to a pair of 2 × 1 and/or 1 × 2 SEs. Other basic characteristics such as insertion loss and cross-talk are also approximated. Finally, the design provides an N × N optical switch composed of N(N - 1)/2 2 × 2 SEs instead of N² for conventional optical cross-bar switches, keeping the strictly non-blocking capability unlike N-stage planar switches, which are rearrangeably non-blocking while composed of the same number of SEs as the design.