Time locking of optical pulses to an external signal in pulsed lasers with active mode locking

Cross-correlation measurements were made of the jitter between the ultrashort pulses emitted by different lasers with active mode locking and synchronised by two methods: by an rf signal and by an external electric pulse. Prelase stabilisation with the aid of a negative-feedback loop ensured that the error in locking ultrashort pulses to the phase of the rf signal, which controlled the mode locker, was ±10 – 15 ps. The error in locking ultrashort pulses to an external trigger pulse was ±130 ps.