Optical clock extraction from 10-Gbit/s data pulses by using monolithic mode-locked laser diodes

An all-optical regenerator, which includes optical decision and optical clock-extraction functions, will extend the maximum transmission distance and relax the design restriction for an optical time-division-multiplexing (OTDM) system. Regarding the optical clock extraction, several experiments employing a self-pulsation laser diode1 and a fiber ring laser2 have been reported. We select and design a mode-locked laser diode (MLLD) as a monolithic optical clock-extraction device with ultrahigh-speed operability. Small size and simple and stable operation are also good features of the MLLD, especially for practical OTDM systems. This paper demonstrates optical clock extraction from 10-Gbit/s data pulses by synchronous mode locking in the monolithic MLLD, for the first time to our knowledge. The excess timing jitter in the optical clock extraction is also evaluated to confirm the practicability of the MLLD.