Fig. 1. Ho∶YAG laser pumped by Tm laser^[17]

Fig. 2. Ho∶YAG laser pumped by 1.91 μm Tm∶YLF solid-state laser^[18]

Fig. 3. Mode-locked Ho∶YAG ceramic laser^[28]

Fig. 4. Self-mode-locked Ho∶YAG laser^[30]

Fig. 5. Twisted-mode Ho∶YAG laser^[34]

Fig. 6. Ho∶YAP laser resonantly pumped by Tm∶YLF laser^[35]

Fig. 7. Ho∶YAP laser pumped by 1930.5 nm TDFA^[36]

Fig. 8. The a-cut Ho∶YAP laser pumped by Tm fiber laser^[37]

Fig. 9. Continuous-wave mode-locked Ho∶YAP laser pumped by Tm fiber laser^[40]

Fig. 10. Ho∶YAP ring laser^[41]

Fig. 11. CW wavelength locked Ho∶CaF₂ laser^[47]

Fig. 12. Passively mode-locked Ho∶YLF laser^[50]

Fig. 13. Ho∶YLF ring laser ^[51]

Fig. 14. Ho∶YVO₄ laser pumped by Tm∶YAP laser^[53]

Fig. 15. Actively Q-switched Ho∶GdVO₄ laser^[54]

Fig. 16. Ho∶YVO₄ unidirectional ring laser^[55]