40-Gbit/s transport system: its WDM upgrade

摘要

Recent Internet traffic growth has accelerated the demand for more capacity. In response to this demand, several Tbit/s-class-capacity experiments have been performed. Figure 1 shows the multiplexing structure of recent Tbit/s capacity experiments. When considering total capacity over terabits per second, there are several advantages to increasing the electrical-TDM (ETDM) channel rate up to 40 Gbit/s. It is possible to reduce the number of multiplexed channels to less than 50, which is very desirable to simplify the network management. 40-Gbit/s LSIs also enable the integration of many network functions into small chips, which is desirable for the reduction of node cost. Figure 2 shows that channel capacity of 40 Gbit/s is the best choice to yield high spectral efficiency approaching the Nyquist limit (1 bit/sHz) In WDM transport system, when considering today's mature WDM multiplexers and demultiplexers with 100-GHz to 200-GHz spacing. Recently, the ETDM channel rate has reached 40 Gbit/s [1] and 40 Gbit/s/channel WDM transport systems have been intensively studied all over the world [2-7]. In this paper, we described the state of the art of transmission technologies for 40 Gbit/s/channel transport systems. The novel configuration of a 40-Gbit/s system prototype and N×40-Gbit/s WDM transmission performance of proposed carrier-suppressed return-to-zero (CS-RZ) format are presented.