Fig. 1. Experiment setup and energy transfer mechanism. (a) Experiment setup of YAG/Tm∶YAG laser intra-cavity pumped Ho∶YAP laser; (b) energy transfer mechanism in intra-cavity pumped Ho∶YAP laser

Fig. 2. Power curve and wavelength drift trend of Tm∶YAG laser when using output coupler with T=2%. (a) Power curve;

Fig. 3. Tm∶YAG laser emission spectrum, and polarized absorption spectra and polarized gain spectra of Ho∶YAP crystal. (a) Tm∶YAG laser emission spectrum and polarized absorption spectra of Ho∶YAP crystal; polarized gain spectra of Ho∶YAP crystal along (b) a-axis, (c) b-axis, and (d) c-axis

Fig. 4. Output power curves of intra-cavity pumped a-cut Ho∶YAP laser. (a) Using output mirrors with different transmissivities;

Fig. 5. Laser spectrum and beam quality of a-cut Ho∶YAP laser measured at maximum power of 9.4 W. (a) Laser spectrum; (b) beam quality

Fig. 6. Output power curves of intra-cavity pumped c-cut Ho∶YAP laser. (a) Using output mirrors with different transmissivities;

Fig. 7. Laser spectrum and beam quality of c-cut Ho∶YAP laser measured at maximum power of 12.07 W. (a) Laser spectrum; (b) beam quality

Fig. 8. Polarized absorption spectra of Ho∶YAP crystal at its lasing bands and characteristic laser wavelengths for a-cut and c-cut Ho∶YAP lasers