Timing stability of active Q-switched mode-locked laser for synchronous laser ranging network

The Communications Research Laboratory (CRL) has been developing a laser time synchronization system based on a satellite laser ranging (SLR). The system directs to control all the firing time of the pulse laser so that each laser pulse reaches at a target satellite exactly on a specified epoch within 100 ns. A conventional Nd:YAG active-passive laser has been upgraded to an active Q-switched mode-locked laser to reduce the firing time jitters with respect to command time. The epoch triggered fire control has also been introduced to ensure command time to take account on prediction, clock error and other fixed delay. It has been demonstrated that the timing stability of firing is several 10 ns level including one way range prediction error to a target satellite