Fig. 1. Thermal model diagram of alexandrite crystal under end pumping

Fig. 2. Crystal temperature field distribution. (a) Variation of end-face temperature in x and y directions when z=0; (b) isotherm and heat flow distribution of end face in x and y directions when z=0

Fig. 3. Deformation field distribution of alexandrite crystal end face under face pumping

Fig. 4. Relationship between thermal focal length and P_in. (a) Thermal focal length ƒ₁ caused by temperature gradient versus P_in; (b) thermal focal length ƒ₂ caused by end deformation versus P_in; (c) thermal focal length ƒ₃ caused by_{thermal stress birefringence versus Pin; (d) comprehensive thermal focal length ƒ versus Pin}

Fig. 5. Schematic of optical path for thermal focal length measurement of alexandrite crystal

Fig. 6. Comparison of thermal focal length and its relationship to stability factor. (a) Thermal focal length versus P_in; (b) relationship between f and |(A+D)/2|

Fig. 7. P_out versus P_in at different L₂

Fig. 8. Output laser spectrum

Fig. 9. Relationship of laser fundamental mode diameter to ƒ and P_in. (a) Laser fundamental mode diameter versus ƒ; (b) laser fundamental mode diameter versus P_in