Abstract

Optical processing has been demonstrated to remove the data flow bottleneck that results at a switch controller when routing decisions are processed electronically.^1,2 Here, optical control of a tree-structured (1 × N) space division photonic switch is reported. A lithium niobate integrated-optic duobanyan switch, with N = 4, is used for the demonstration.³ Each data bit 1 is subencoded with a binary route address by dividing the bit interval into a frame of M + 1 time slots, where M is the number of stages in the switch (M = log₂N). The 0th slot is occupied by a reference pulse. Binary information in time slot j, j = 1,…, M, determines the state of the switching elements in the jth stage of the switch. To route a bit to the desired switch output port, an optical routing controller decodes the route through the switch, stage-by-stage, and sets all switching elements in each stage of the switch accordingly. Since a time reference is transmitted along with the data, no external synchronization is required at the optical routing controller. Extension of this self-routing technique to N × N switching architectures, based on a tree structure,⁴ as well as its use in packet/circuit switching, are discussed.

© 1989 Optical Society of America