Beam quality improvements by a large margin for signal and idler beams of a high energy 100 Hz KTiOAsO4 (KTA) non-critical phase matching (NCPM) optical parametric oscillator (OPO) were demonstrated using an unstable resonator configuration instead of a plane-parallel one. Theoretically, influences of cavity lengths and transmission of an output coupler on the OPO conversion efficiency for both were numerically simulated. For OPO based on an unstable resonator with a Gaussian reflectivity mirror, the maximum pulse energies at the signal (1.53 µm) and idler (3.47 µm) were about 75 mJ and 26 mJ, respectively. The corresponding beam quality factors of the signal were Mx2 = 9.8 and My2 = 9.9, and Mx2 = 11.2 and My2 = 11.5 for the idler. As a comparison, 128 mJ of signal and 48 mJ of idler were obtained with the plane-parallel resonator, and the M2 factors of the signal were Mx2 = 39.8 and My2 = 38.4, and Mx2 = 32.1 and My2 = 31.4 for the idler. Compared with a plane-parallel cavity, over eight times and three times brightness improvements were realized for the signal and idler light, respectively.

中文翻译：

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使用带有高斯反射镜的不稳定谐振器对基于 NCPM-KTA 的高能光学参量振荡器的光束质量改进进行研究 [特邀]

使用不稳定的谐振器配置而不是平面平行配置，证明了高能量 100 Hz KTiOAsO4 (KTA) 非关键相位匹配 (NCPM) 光学参量振荡器 (OPO) 的信号和闲散光束的光束质量大幅提高. 理论上，数值模拟了腔长和输出耦合器的传输对两者的OPO转换效率的影响。对于基于带有高斯反射镜的不稳定谐振器的 OPO，信号 (1.53 µm) 和闲散 (3.47 µm) 处的最大脉冲能量分别约为 75 mJ 和 26 mJ。信号的相应光束品质因数为 Mx2 = 9.8 和 My2 = 9.9，而闲散光的 Mx2 = 11.2 和 My2 = 11.5。作为比较，使用平面平行谐振器获得了 128 mJ 的信号和 48 mJ 的惰轮，并且信号的 M2 因子为 Mx2 = 39.8 和 My2 = 38.4，对于惰轮，Mx2 = 32.1 和 My2 = 31.4。与平面平行腔相比，信号光和闲散光分别实现了八倍以上和三倍的亮度提升。