Introducing a 2V-resonator for the improvement of pulse stability in a high-gain Q-switched Yb:YAG thin-disk laser

Pulse instability in Q-switched solid-state lasers at enough high repetition rates is a significant problem for getting high powers. This issue is more critical for Thin-Disk-Lasers (TDLs) due to the smallness of round-trip gain in the thin active media. The main idea of this work is that increasing the round-trip gain of a TDL makes it possible to diminish its pulse instability at high repetition rates. Accordingly, a novel 2V-resonator is introduced to overcome the low gain of TDLs, in which the passage of the laser beam from the active media is twice that of the standard V-resonator. The experiment and simulation results indicate that the threshold of laser instability considerably improves for the 2V-resonator relative to the traditional V-resonator. This improvement is well seen for various time windows of the Q-switching gate and different pump powers. By choosing appropriate Q-switching time and pump power, the laser was stably run at 18 kHz, a recorded repetition rate for Q-switched TDLs.