Generation of a 300-psec pulse by direct mode locking of a long-pulse XeCl laser

A pulse duration of 300 psec has been achieved by direct mode locking of a long-pulse (150-nsec) XeCl laser by using an acousto-optic modulator and a saturable absorber (BBQ). The pulse duration was found to depend considerably on intensity level, and the shortest duration was observed in a train with 4-5 pulses. The time evolution of successive pulses pursued by a streak camera showed that a drastic reduction in the pulse duration occurred after the peak pulse in the train.