N-stage planar optical permutation network.

This paper describes the construction of a permutation network which is advantageous for optical switching. The switching architecture is planar and does not require optical path crossovers between crosspoints. The network can be partitioned if necessary to ease fabrication difficulties. An algorithm is given to set the binary cells in the network to achieve any specified permutation, and it is shown that no planar N x N network can achieve such rearrangeability with fewer than the N(N - l)/2 crosspoints used here.