Abstract

As applications for lightwave systems expand, new challenges for photonic switches are constantly evolving and some of these challenges can be satisfied by moving-fiber type switches. In the case of optical fiber networks having many regenerative nodes, it is necessary to bypass those nodes that are not in use and to ensure that in-operative nodes are not permitted to enter the network and cause a total network failure.¹ In this paper, we report on a moving-fiber-array switch that provides these important switching functions in evolving single-mode fiber (SMF) networks. In particular, the switch is designed to provide the bypass function through only one SMF butt-joint; therefore, it exhibits very low insertion loss and permits networks to be designed that have a large number of off-line nodes for a large percentage of the time. A second feature of this switch is that while in the bypass position the switch establishes an optical loop-back circuit, for the regenerative node (a receiver/transmitter combination), permitting self-testing of the node. If the self-test is negative, due to an in-operative node, then the switching function (switching to the on-line position) can be blocked thereby avoiding a total network failure. In the event a node failure occurs after switching, the actuator is de-energized and the switch returns to the normal position (bypass position). In the on-line position the optical path through the switch uses low loss single-mode fiber to multimode fiber (SMF/MMF) "photon-bucket" type joints between the line input and the node’s receiver, and again only one SMF/SMF joint between the node’s transmitting SMF and the network’s SMF. Solenoid actuation is used for achieving the on-line position and a compression spring is used to return and hold the switch in the bypass position.

© 1987 Optical Society of America