Investigation on multiple soliton operations in erbium-doped fiber lasers based on Bi2O2Te saturable absorbers

In this experiment, a Bi₂O₂Te nanosheet solution was prepared by the liquid phase exfoliation (LPE) method. By placing the Bi₂O₂Te nanosheet solution on a tapered fiber, a saturable absorber (SA) was formed. A Bi₂O₂Te-SA ring cavity system based on the 1.5 μm band was constructed, thus realizing the application of Bi₂O₂Te in erbium doped fiber lasers (EDFLs). Within the pump power range of 252 mW–427 mW, stable conventional soliton mode locked pulses (CS) were successfully obtained. Its 3 dB bandwidth was 2.18 nm, and the maximum pulse energy was 110.46 pJ. Subsequently, by adjusting the pump power and the polarization state in the cavity, a stable second order harmonic mode locked pulse (HML) was obtained when the pump power was 417 mW. Its 3 dB bandwidth was 2.80 nm. In addition, at pump powers of 369 mW, 379 mW and 406 mW, stable two-pulses, three-pulses and four-pulses were obtained respectively. This was the first time that multi-pulse operation was achieved in a fiber laser based on Bi₂O₂Te-SA. The experimental results show that Bi₂O₂Te has excellent nonlinear optical modulation performance and has broad research prospects in soliton evolution. The applications of abundant soliton states in fields such as quantum computing and quantum communication are also worth looking forward to.