Fig. 1. GSBT films pictures

Fig. 2. Schematic diagram of fiber laser system

Fig. 3. XRD images of GSBT films before and after annealing

Fig. 4. Absorption spectra of aGSBT and cGSBT

Fig. 5. Nonlinear characteristic curves of GSBT films

Fig. 6. Atomic arrangement of GSBT

Fig. 7. Output characteristics of the mode-locked laser based on cGSBT saturable absorber

Fig. 8. Absorption spectra of GSBT films of 40，60，80 nm