System Demonstrations and Assessment of Optical Switching in Broadband Networks

Abstract

Although optical switching has generated for more than a decade a lot of interest within the research community, it is only more recently that the more credible application scenarios have been proposed. The new element is in fact the commercial introduction — faster than it was initially thought — of Wavelength Division Multiplexing (WDM) transmissions [1]. The reasons for this are both economical (progressive and cost effective upgrade of transmission capacity in WDM) and technical (fibre limitations such as Polarisation Mode Dispersion can limit the bitrate x distance product, availability of DFB lasers with well precise and stable wavelength, Erbium Doped Fibre Amplifiers which support WDM channels). The introduction of WDM transmission can not be seen as going against Time Division Multiplexing (TDM) system, since WDM of course do use TDM signals on each wavelength channel. Rather, one can expect that for a given capacity and given installed network, WDM will allow an earlier solution as compared to all TDM system. One can anticipate that together with Nx2.5Gb/s WDM systems, which are in commercial use today, one will see the emergence of Nxl0 Gb/s systems before the end of the decade.