MODE-LOCKING OF CW LASERS BY REGENERATIVE RF FEEDBACK

Abstract

Dynamic mode locking of a He–Ne laser was accomplished by detecting the rf beats between axial modes, and by using this signal as external regenerative feedback to the laser, making the system a self-oscillator at the axial mode difference frequency of 75 MHz. The feedback signal was applied to the laser by means of a KD*P longitudinal modulator placed in the laser cavity to provide phase modulation. The average output power of the laser was 50 mW; the peak pulse power was about 1.25 W.