We achieved a dispersion tolerance of 25-ps/nm at 80-Gbit/s using novel carrier-suppressed return-to-zero (CS-RZ) coding realized by duty ratio and optical multiplexing phase control. We also show that the dispersion tolerance strongly depends on the relative optical phase difference between adjacent time slots, and demonstrate 80-Gbit/s 60-km DSF transmission without dispersion compensation by using a newly-fabricated stable 80-Gbit/s OTDM transmitter.

We demonstrate a simple BER monitoring method for WDM signals. Newly developed 32-channel wavelength selector based on thermo-optic switch and AWG is used. The BER of each channel is estimated from opened eye-diagrams obtained by asynchronous sampling. Good BER monitoring performance is confirmed.

The objective of this paper is to survey the Generalized Multi-Protocol Label Switching (GMPLS) based recovery technology for optical transport networks. This paper introduces standardization activities of the GMPLS based recovery technology in the Internet Engineering Task Force (IETF), and recent progress of related experiments. In addition, this paper extracts requirements for the GMPLS based recovery technology through the evaluation of existing network elements, which can be client nodes of the optical transport networks. The results of field evaluations on the GMPLS based recovery technology are also introduced in this paper. Then, this paper addresses the issues for future deployment of the GMPLS based recovery technology for the optical transport networks.

This paper presents 160-Gbit/s full channel time-division demultiplexing using a semiconductor optical amplifier hybrid integrated demultiplexer on a planer lightwave circuit. Error-free demultiplexing from a 160-Gbit/s signal to 8 channel 20 Gbit/s signals is successfully demonstrated. Results of a 160-Gbit/s optical time-division-multiplexed full channel OTDM signal transmission experiment using the circuit and successful 80-km transmission are presented.