1338-nm Single Wavelength Operation of Acousto-Optic Q-Switched Nd:YAG Laser

We demonstrated a high-peak-power acousto-optic Q-switched Nd:YAG laser emitting at 1338 nm. The resonator adopted a symmetrical convex-convex cavity with a two-rod configuration, which is side-pumped by a $\mu $ s long pulse laser diode. At the beginning, the free running mode and Q-switched mode operated with single-wavelength emission at 1319 nm and dual-wavelength emission at 1319 and 1338 nm, respectively. By means of using a 8 mm-thick birefringence filter to increase the intra-cavity loss at 1319 nm, single wavelength operation of 1338 nm was achieved with spectral width of 0.31 nm. Under the pump power of 390 W, the Q-switched laser delivers 28.7 W of average output power with an optical conversion efficiency of 7.4%. The pulse width was measured to be 124 ns with a repetition rate of 400 Hz, and the corresponding peak power is up to 0.58 MW.