Fig. 1. Experimental setup for in-band LD-pumped thulium-doped laser

Fig. 2. Output spectra of LD pump source and absorption spectra of thulium-doped medium. (a) Spectra of LD pump source under different output powers; (b) absorption spectra of Tm∶YAP and Tm∶YAG

Fig. 3. Ground state absorption corresponding to ³H₆→³F₄ transition and laser transition from ³F₄ to ³H₆ in Tm∶YAP

Fig. 4. Output powers and corresponding laser spectra of 785 nm LD-pumped thulium-doped laser. (a) Tm∶YAP crystal; (b) Tm∶YAG crystal

Fig. 5. Beam quality of 785 nm LD-pumped Tm∶YAP laser at maximum output power. (a) x direction; (b) y direction

Fig. 6. Pump absorptivity of thulium-doped medium at 1700 nm versus incident pump power. （a） Tm∶YAP crystal； （b） Tm∶YAG crystal

Fig. 7. Output powers and corresponding laser spectra of 1700 nm LD-pumped thulium-doped laser. (a) Tm∶YAP crystal; (b) Tm∶YAG crystal

Fig. 8. Output power stability curves of 1700 nm in-band LD-pumped Tm∶YAP laser. (a) Temperature stability; （b） time stability

Fig. 9. Beam quality of 1700 nm LD-pumped Tm∶YAP laser at maximum output power. (a) x direction; (b) y direction

Fig. 10. Output characteristics of 1700 nm LD-pumped Tm∶YAP/Ho∶Y₂O₃ laser. (a) Output power curve; (b) laser spectrum