NEW ARCHITECTURES FOR OPTICAL TDM SWITCHING

Time division multiplexing (TDM) is a natural multiplexing format for many services that will be found in future optical telecommunications networks, such as high definition television (HDTV) and videophone. This paper is the first part of a systematic theoretical study of architectures for optical TDM switching, using lithium niobate optical switches, with optical fiber delay lines for storage. The architectures allow the bitrate and wavelength transparency of these devices to be exploited. A technique involving recursive definition and proof is used to define the networks, which are mathematically related to Benes and Waksman networks. This produces architectures that are very different from existing optical TDM networks. They exhibit economical use of components, which reaches the theoretical minimum in some cases. Also, the use of ''feed-forward'' rather than ''feed-back'' delays give these networks superior crosstalk performance and more uniform attenuation than existing designs. Dilated Benes networks are generalized so that all the networks proposed here can be dilated. This drastically reduces crosstalk at the expense of roughly doubling the number of switches. Attenuation is also studied, and it is found that by constructing the network properly, it can be reorganized onto only a few substrates, greatly reducing attenuation. Network architectures both having and lacking frame integrity are considered.