Optical Components for WDM Lightwave Networks

Recently, there has been growing interest in developing optical ber networks to support the increasing bandwidth demands of multimedia applications, such as video conferencing and World Wide Web browsing. One technique for accessing the huge bandwidth available in an optical ber is wavelengthdivision multiplexing (WDM). Under WDM, the optical ber bandwidth is divided into a number of non-overlapping wavelength bands, each of which may be accessed at peak electronic rates by an end user. By utilizing WDM in optical networks, we can achieve link capacities on the order of 50 Terahertz. The success of WDM networks depends heavily on the available optical device technology. This paper is intended as a tutorial on some of the optical device issues in WDM networks. It discusses the basic principles of optical transmission in ber, and reviews the current state of the art in optical device technology. It introduces some of the basic components in WDM networks, discusses various implementations of these components, and provides insights into their capabilities and limitations. Then, this paper demonstrates how various optical components can be incorporated into WDM optical networks for both local and wide-area applications. Finally, the paper provides a brief review of experimental WDM networks which have been implemented. keywords: lightwave network, wavelength-division multiplexing, device issues, optical ber, tunable transmitter, tunable receiver, optical ampli er, switching elements, wavelength converter, experimental systems.