Modified gamma network and its optical implementation

A modified gamma network that is based on the bar-plus-2(i) and modulo-N connection patterns is proposed. The gamma network, one class of important O (N log(2)N) interconnection networks, needs arrays of 1 × 3 or 3 × 3 switches, which makes it difficult to realize in optics. We modify the gamma network to meet the characteristics of optics by employing a bar-plus-2(i) connection pattern and a modulo N output stage. Two-by-two switches and regular interconnections are used in the network, so the network is suitable for optics. The optical implementation of the network with a birefringent crystal and an array of programmable half-wave plates is suggested, and a proof-of-principle experiment is presented. The network is a rearrangeable nonblocking network, and the nonblocking routing algorithm for an N × N network is given; (2 log(2)N - 2) switching stages [with a total of (2 log(2)N + 1/2)N - 4 log(2)N - 1 switches] can permute N input nodes to N output nodes in any order in a one-to-one manner. The network is applicable to packet synchronous optical traffic.