Repetition-rate-tunable second harmonic generation in mode-locked optically pumped semiconductor disk laser

We demonstrated a repetition-rate-tunable second harmonic mode-locked optically pumped semiconductor disk laser (OP-SDL), and the tuning range was from 1.168 GHz to 1.25 GHz. The entire tuning process was continuous, and OP-SDL was always in a mode-locked working state. To the best of our knowledge, this is the first work to obtain intracavity repetition rate tunable second harmonic laser in an OP-SDL. At same time, the repetition rate of fundamental wave can be continuously adjusted from 1.16 GHz to 1.66 GHz. The central wavelengths of the pulse trains were around 971 nm, and the highest repetition rate signal-to-noise ratio was more than 60 dB, indicating that the mode-locked pulses were stable.