Fig. 1. Experimental setup for the high beam quality idler resonant MgO:PPLN-OPO

Fig. 2. Spatial distribution. (a) 1.064 µm pump beams; (b) 1.522 µm signal beams; (c) 3.534 µm idler beams

Fig. 3. Near-infrared (1.522 μm) signal beams and mid-infrared (3.534 μm) idler beams energies as a function of the pump beams energy at crystal temperature of 110 ℃

Fig. 4. Wavelength tuning curves of the OPO outputs versus the temperature of the MgO:PPLN crystal

Fig. 5. Mid-infrared idler beams output energy of the wavelength tuning at a pump energy of 21 mJ

Fig. 6. Beam quality measurement of the mid-infrared idler beams at 3.534 μm