Fig. 1. Schematic diagram of laser structure used in simulation calculation

Fig. 2. Flow chart of lower energy level algorithm (LELA)

Fig. 3. Simulation results and experimental comparison of two algorithms at pump power of 80 W

Fig. 4. Simulation results and experimental comparison of two algorithms at pump power of 90 W

Fig. 5. Simulation results and experimental comparison of two algorithms at pump power of 100 W

Fig. 6. Variation trend of upper energy-level population and inverted population at pump power of 100 W