Fig. 1. Schematic diagram of a four-mirror non-planar ring resonator mid-infrared OPO laser.中红外OPO四镜非平面环形腔示意图

Fig. 2. Diagram of reference frame and image rotation for nonparallel planes of incidence.非平行入射平面的参考系和像旋转示意图

Fig. 3. Example of a four-mirror nonplanar ring resonator.简单四镜非平面环形腔示意图

Fig. 4. Two equivalent sphere representations of a four-mirror nonplanar ring resonator:　(a) Transparent equivalent unit sphere; (b) non-transparent equivalent unit sphere四镜非平面环形腔的两种等效球体表示方式　(a) 透明等效单位球体; (b) 非透明等效单位球体

Fig. 5. Diagram and unit sphere representation of a 90^° image rotating four-mirror non-planar ring resonator. 90^°像旋转四镜非平面环形腔三视图及单位球表示

Fig. 6. The intensity distribution of transverse mode in a four-mirror non-planar ring resonator at different rotation angles:　(a) The intensity distribution at 0^° rotation angle; (b) the intensity distribution at 5^° rotation angle; (c) the intensity distribution at 45^° rotation angle; (d) the intensity distribution at 90^° rotation angle. 不同旋转角下四镜非平面环形腔内横模光强分布　(a) 0^°旋转角光强分布; (b) 5^°旋转角光强分布; (c) 45^°旋转角光强分布; (d) 90^°旋转角光强分布

Fig. 7. The intensity distribution of transverse mode in a 90^° image rotating four-mirror non-planar ring resonator:　(a) TEM₀₀ mode; (b) TEM₀₁ mode; (c) TEM₁₀ mode 90^°像旋转四镜非平面环形腔内横模光强分布　(a) TEM₀₀模; (b) TEM₀₁模; (c) TEM₁₀模

Fig. 8. The beam quality based on ZnGeP₂ OPO in different resonators:　(a) Plano-plano resonator; (b) 90^° image rotating four-mirror non-planar ring resonator. 不同腔型下中红外ZnGeP₂ OPO输出光束质量　(a) 平平腔; (b) 90^°像旋转四镜非平面环形腔