An optical multiaccessor designed for a fiber-optic star-ring LAN

Abstract

An optical waveguide-type multiaccessor for physically star and logically ring local area networks (star-ring LANs) has been manufactured. The multiaccessor has sufficient low optical transmission loss to bypass some failure nodes without an optical repeater. As the multiaccessor (eight-node-connection type) features are small size, 5 cm square by 0.5 cm thick, a smaller cable concentrator can be applied. The design method used for the multiaccessor to minimize total optical transmission loss caused by both signal interference loss and bypassing loss when failure nodes are bypassed in the star-ring LAN is described. The experimental results for the 32 Mb/s single-mode fiber-optic star-ring system show that at least three nodes can be continuously bypassed by using the multiaccessor with a coupling ratio of 0.5 and a bypass loss of 3 dB. As a result, highly reliable and inexpensive star-ring LANs can be designed with the multiaccessor. >