Abstract:
In order to meet the engineering application of mid-infrared laser, a miniaturized mid-infrared MgO: PPLN optical parametric oscillator (MgO: PPLN-OPO) with high beam quality was presented. The pump source was an acousto-optical Q-switched Nd: YVO
4 laser. By pumping the MgO: PPLN crystal, the mid-infrared laser with high efficiency and high peak power was obtained. And the mid-infrared beam quality was improved by adding an aperture in the cavity. The whole laser was cooled by thermoelectric cooling and air cooling. Therefore, the size of the laser was miniaturized. Experimental results indicate that the acousto-optical Q-switched Nd: YVO
4 laser can realize the pulse laser with the highest power of 9.3 W at 1.064 μm. The corresponding optical to optical conversion efficiency is 27.2% and the peak power is ~27.5 kW. With the Nd: YVO
4 laser pump, the MgO: PPLN-OPO can output the pulse laser at 3.765 μm. When adding the aperture in the cavity, the maximum output power of the MgO: PPLN-OPO decreases from 1.20 W to 1.08 W. However, the beam quality improves obviously. The
Mx2 and
My2factors change from 1.89 and 1.98 to 1.20 and 1.29, respectively. The pulse width and the peak power of mid-infrared laser are 8.4 ns and ~4.3 kW, respectively.