Designing Optical Networks from Simple Switching Elements

Abstract

An analysis of switching networks and current optical technology reveals that the topology of networks determines the extent to which optics can offer system-level performance advantages over electronic and electrical implementations. For direct connection networks such as mesh networks, hybrid electrooptical networks that employ circuit switching can reduce latency and thereby system throughput by an order of magnitude. For packet switched local area networks, optically controlled electrooptic waveguide crossbar networks provide higher efficiency and also lower latency advantages. To illustrate our thesis, we present two examples of electrooptical waveguide-based network designs. In the first, we describe a new self-routing optical crossbar design, VIPER +, that can be realized by locally controlled 2 × 2 electrooptic switches. The VIPER + crossbar is unique in that it can solve the network access and conflict arbitration problems optoelectronically. Further, by cascading the proposed crossbar networks, larger nonblocking self-routing optical networks can be implemented in modular fashion. The second design based on VIPER + is a waveguide mesh interconnection network that incorporates an optical express router, in which optical channels are accessed for remote processor communications, in an electrical mesh.