Fig. 1. Raman spectroscopy. (a) GQDs-SA; (b) MoS₂-SA

Fig. 2. Transmission spectroscopy. (a) GQDs-SA; (b) MoS₂-SA

Fig. 3. Nonlinear transmission characteristics. (a) GQDs-SA; (b) MoS₂-SA

Fig. 4. Double passively Q-switched laser experimental device based on GQDs-SA & MoS₂-SA

Fig. 5. Relationship between average output power and pump power

Fig. 6. Pulse laser output characteristics. (a) Relationship between pulse width and pump power; (b) relationship between repetition rate and pump power

Fig. 7. Output characteristics of the pulse laser, when the pump power is 12.9 W. (a)--(c) Single pulse waveform of GQDs, MoS₂, and GQDs & MoS₂ respectively; (d) pulse sequence of GQDs & MoS₂

Fig. 8. Stability of the pulse laser, when the pump power is 12.9 W. (a) Laser spectrum, inset is the 1064 nm beam profile; (b) radio frequency spectrum; (c) graph of output power change over time