Abstract

While optical transmission systems with the TDM data rate of 40 Gbit/s are becoming commercially available now, the next generation TDM data rate of 160 Gbit/s is under active study in many laboratories. One critical issue for deploying such high-bit rate systems is the availabil ity of in-service quality monitoring at the full line rate, regardless of the data protocol. Optical sampling systems that rely on the fast nonlinearity of crystals, ^1,2 fibers^3,4 or semiconductor optical amplifiers^5,6 provide the picosecond timing resolution needed. It has been shown that such systems can be used to evaluate the quality of an optical data signal⁷ by calculating Q-factors from the measured eye diagrams. However, in addition to a good timing resolution, a practical monitoring system should incorporate a clock recovery to allow measurements anywhere along the transmission link. This was only realized in⁵ up to now. Also, the persistence times should be appropriate to collect sufficient statistical data for a valid Q-factor calculation.

© 2002 Optical Society of America