Frequency-offsetted cavity-length control loop in a diode-laser-pumped and actively mode-locked Nd:YLF laser

We have demonstrated a novel stabilization feedback control of an acousto-optically mode-locked laser. A frequency offset of 6 Hz is maintained between the laser repetition rate and the double of the acousto-optical modulator (AOM) driving frequency. The offset is limited by the response time of the feedback control circuitry, which is estimated to be about 100 ms. In this way, real-time optoelectronic sampling measurements can be performed by triggering with the AOM driving frequency while sampling with the laser repetition frequency. As a result, time-resolved measurements are greatly simplified when compared with those performed by the delay-line pump-probe technique.