640-Gb/s OTDM signal measurement with high-resolution optical sampling system using wavelength-tunable soliton pulses

We have demonstrated an optical sampling system using wavelength-tunable soliton pulses produced by a highly nonlinear polarization-maintaining (PM) fiber. We successfully observed a 640-Gb/s optical signal with the system. The wavelength of the sampling pulses was shifted to 1736 nm by employing a 40-m-long PM fiber, and the sampling pulsewidth was 210 fs. The system achieved high temporal resolution of 280 fs and high sensitivity by employing a 2-mm-thick periodically poled LiNbO/sub 3/ crystal. The system jitter was estimated to be 80 fs.