Fig. 1. Pupil shift phenomenon when the incident laser is parallel to the optic axis

Fig. 2. Displacement of the incident laser beam in the thin-disks and coolants

Fig. 3. Relationship among the cutting angle of the disk, the displacement and the incident angle of the laser

Fig. 4. (a) Schematic of the gain module; (b) top view of the gain module; (c) single flow channel

Fig. 5. (a) Contraction section curve; (b) diffuser section curve

Fig. 6. Side-pumped structure in the direct-liquid-cooled thin-disk laser

Fig. 7. Two side-pumped methods. (a) Non-uniform pump; (b) uniform pump

Fig. 8. End-pumped structure in the direct-liquid-cooled thin-disk laser

Fig. 9. (a) Output power varying with different reflectivities; (b) output power varying with pump power at the optimum reflectivity

Fig. 10. Experimental setup of the kilowatt-level direct-liquid-cooled Nd∶YLF thin disk resonator