Fig. 1. Schematic diagram of the experiment setup. (a) Multi-point pumped SDL with an intra-cavity transmission grating. (b) The geometric relationship of pump spots and transmission diffraction grating. (c) Linear straight cavity with the same cavity length as (a).

Fig. 2. (a) Output power curve of the linear straight cavity and the cavity with transmission grating. Inset: spectrum measured at 29.3 W pump power. (b) Laser beam waist size of the two cavities at different pump power. (c) Output power curve of the two cavities in units of kW/cm².

Fig. 3. (a) Emission spectrum at different output powers in the linear straight cavity. (b) Spectrum and maximum output power of the cavity with transmission grating measured at different wavelength tuning points.

Fig. 4. Output power curve of multi-point pump SDL with an intra-cavity transmission grating. (a) No. 1 and No. 3 two-point synchronous pumping. (b) No. 1, No. 2, and No. 3 three-point synchronous pumping.

Fig. 5. Pump-power-dependent M² factors for (a) the linear straight cavity, (b) No. 2 single-point pumping cavity with transmission grating, (c) No. 1, No. 2, and No. 3 three-point pumping cavity.