Fig. 1. (a) Conversion efficiency versus crystal length at 50% transmittance of the OC. (b) Conversion efficiency versus transmittance of the OC at the crystal length of 33 mm.

Fig. 2. Schematic diagram of the experimental setup of the KTA-OPO system. HR, high reflection; 90°QR, 90° quartz rotator; BP, beam polarizer; GRM1, Gaussian reflectivity mirror for 1.06 µm; ISO, isolator; M1, mirror 1; GRM2, Gaussian reflectivity mirror for 1.5 µm; M2, 45° beam splitter.

Fig. 3. (a) Output energy change with the pump current. Inset shows the temporal pulse profile at maximum output power. (b) Beam quality of the energy at 480 mJ. Inset shows the beam profile.

Fig. 4. OPO output pulse energies (sum of signal and idler) for unstable and stable resonators. (a) Output energies versus the incident pump energy at the cavity length of 90 mm. (b) Output energies under different cavity lengths at the pump energy of 480 mJ.

Fig. 5. Beam quality of the signal and idler at the pump energy of 480 mJ. Inset shows the beam profile. (a) Signal of the OPO based on the plane-parallel cavity; (b) idler of the OPO based on the plane-parallel cavity; (c) signal of the OPO based on the unstable cavity with GRM; (d) idler of the OPO based on the unstable cavity with GRM.

Fig. 6. Spectrum of the signal light.

Fig. 7. Typical pulse shapes of OPO based on the unstable cavity with GRM at the output energy of 101 mJ. (a) Temporal profile of the signal in the experiment; (b) temporal profile of the idler in the experiment; (c) the simulation of the temporal profile.