6 – Ultra-high-speed OTDM transmission technology

Publisher Summary This chapter discusses ultra-high-speed data transmission in optical fibers based on optical multiplexing (OTDM) technology, giving a general description of an OTDM system, the OTDM transmitter, the OTDM receiver, and the fiber transmission line. For 160 Gb/s TDM transmission, there are several optical signal processing technologies available. Presently, the optimum terminal equipment includes an optical gate and a clock recovery device in the receiver both based on EAMs and an MLLD as pulse source in the transmitter. Based on this terminal equipment, 160 Gb/s OTDM point-to-point transmission technology seems to be nearly a mature technology. Combined with the modulation format differential phase-shift keying (DPSK) and balanced detection, it provides very stable operation. Today, commercial systems use ETDM and not OTDM. The present research work on ETDM technology focuses on 100 Gb/s Ethernet rather than on the next bit rate in the STM hierarchy, which would be 160 Gb/s. An optical network also comprises networking components, like add/drop multiplexers, 3R-regenerators, etc. The principal operation of these networking components has been shown based on OTDM technology at 160 Gb/s. A possible scenario for future communication networks with a TDM data rate of 160 Gb/s is that these networks use a hybrid technology based on a mixture of OTDM and ETDM technologies. Transmission at data rates beyond 160 Gb/s will require not only appropriate terminal equipment but also improved transmission fibers and improved in-line amplifiers.