Abstract

The usable transmission bandwidth of a single-mode optical fiber is enormous (as much as 50,000 GHz). Existing systems barely scratch the surface of this vast untapped resource. We propose a novel scheme for a local fiber-optic communications network that supports tens of thousands of simultaneous users, each requiring a several Mb/s continuous data rate. The system uses coherent optical techniques¹ to exploit the vast fiber bandwidth. A spread-spectrum technique² is used to circumvent the problems caused by the instabilities of present-day semiconductor lasers, e.g., the difficulty in reliably setting a laser's frequency with an accuracy better than several hundred gigahertz. Another mitigated problem is phase noise in the laser output.³ which would otherwise result in excessive amounts of interference among the various users.

© 1987 Optical Society of America