Load Balanced Two-Stage Switches Using Arrayed Waveguide Grating Routers

Constructing a load balanced two-stage switch using optical switch fabrics must properly address the non-negligible amount of switch reconfiguration overhead. Unlike other optical switch fabrics, an NtimesN arrayed waveguide grating router (AWGR) allows N² parallel connections (one on each wavelength) established between its N inputs and N outputs. This eliminates the need for switch reconfigurations. In this paper, we design a load-balanced two-stage switch using AWGRs. In particular, we adopt the efficient feedback-based two-stage switch architecture. The key issue is how to implement the joint sequence of N switch configurations logically in AWGR. We show that the resulting logical joint sequence inherits the original staggered symmetry property as well as the in-order packet delivery property. Since building a large sized AWGR is difficult, a systematic approach of constructing large AWGR from smaller AWGR modules is also proposed. Simulations show that the feedback-based two-stage switch using AWGRs gives an excellent overall delay-throughput performance under various traffic conditions.