Optical switching systems

Two broad approaches are discussed. One approach is to code the source or destination by means of wavelength. Such an approach is clearly very attractive for local broadband networks serving modest numbers of terminals (30-100 or perhaps more). It could be extended to a much larger multimode network. It is assumed that a national network could be served by a modest number of major nodes (30-100), coded by a unique wavelength. The nodes then appear to take the form of passive wavelength multiplexers, but dealing with collisions or contention is less simple. The alternative route is to stay with packet (ATM) transmission and to seek ways of using the digital header address to self-route a signal. The problems and possibilities are examined, and the necessary technical developments are discussed.<>