Abstract

Several-tens giga bit digital optical transmission systems would require ultrafast waveform measurements of light pulses with a time resolution of less than ten picoseconds. The optical sampling technique^(1,2) utilizing ultrashort laser diode pulses offers an attractive method that avoids problems associated with high-speed electronics. Recently, gain-switched, pulse-compressed distributed-feedback-laser diodes (DFB-LDs) have been used to achieve a time resolution of 8.7 ps⁽¹⁾, where a bulk crystal of LiIO₃ was used as an optical sum-frequency generator. This paper reports the first observation of a 25 Gbit/s word pattern with a time resolution of less than 9 ps utilizing a LiNbO₃ waveguide, where the sum-frequency signal is emitted as the "Cherenkov radiation" mode. This waveguide approach has two advantages of high conversion efficiency and wide matching bandwidth.

© 1988 Optical Society of America