Langasite electro-optic Q-switched 2 mu m laser with high repetition rates and reduced driven voltages

摘要

Mid-infrared electro-optic Q-switched lasers with high repetition rates have many vital applications. However, the required voltage of electro-optic Q-switching is proportional to the wavelength leading to the severe piezoelectric ring effect, which limits its developments especially with high repetition rates. Based on the rate equation, this work designs a Langasite (LGS) electro-optic Q-switched laser with high repetition rates at 2 mu m by balancing the gain and loss in the cavity. The driven voltage determines the rotation of the polarization corresponding the loss in the cavity, and the gain depends on the incident pump power and repetition rate. By theoretical calculation, the driven voltage used in the high repetition rates is reduced to be 3.9 kV, which is 45% lower than the quarter-wave voltage. We demonstrated the LGS electro-optic Q-switched 2 mu m laser with a repetition rate of 200 kHz and pulse width of 5.52 ns. To the best of our knowledge, this work presents the highest repetition rate in the electric-optic Q-switched laser at 2 mu m and should be helpful for the design of Q-switched lasers with high repetition rates.