Optical Multistage Interconnection Networks: New Challenges and Approaches

Optical interconnections for communication networks and multi-processor systems have been studied extensively. A basic element of optical switching networks is a directional coupler with two inputs and two outputs or switching elements. Depending on the control voltage applied to it, an input optical signal is coupled to either of the two outputs, setting the SE to either the straight or cross state. A class of topologies that can be used to construct optical networks is multistage interconnection networks, which interconnect their inputs and outputs via several stages of SEs. Although optical MINs hold great promise and have demonstrated advantages over their electronic counterparts, they also introduce new challenges such as how to deal with the unique problem of avoiding crosstalk in the SEs. In this article we survey the research carried out, including major challenges encountered and approaches taken, during the past few years on optical MINs.