Fig. 1. Orthographic drawing of a surface-doped slab.

Fig. 2. (a) Temperature distribution along the thickness at y=14, z=1.25; (b) temperature distribution along the length at x=0.27, y=14. The slab has outside dimensions of 28 mm width by 113.2 mm length by 2 mm thickness, consisting of a 0.27 mm-thickness Yb3+-doping surface with a concentration of 2 at. %, and the slab is double-end-pumped with a pump power of 30 kW at 940 nm.

Fig. 3. Comparison of the highest temperature of the surface-doped slab and the normal bulk-doped slab over a wide pump power range.

Fig. 4. Schematic diagram of the laser beam path in the slab.

Fig. 5. Energy level scheme of the Yb:YAG laser system. The Boltzmann occupation factors of the Stark levels coupled by the pump radiation are denoted by fap and fbp. The Boltzmann occupation factors of the Stark levels coupled by the laser emission are denoted by fal and fbl.

Fig. 6. Curves of the absorbed efficiency and the output power with different thicknesses of the doped region, when the pump power is 30 kW and the output coupler reflectivity R is 0.75.

Fig. 7. Predicted laser output power and optical-optical conversion efficiency against the pump power with an output coupler reflectivity R of 0.75. The pump power at the lasing threshold is about 3.4 kW and the slope efficiency is 60.2%.

Fig. 8. Schematic of the experimental setup.

Fig. 9. Laser oscillator performance for a 48 J double-end-pumped surface-doped Yb:YAG slab laser.