Positive dispersive ring cavity erbium-doped fiber lasers based on Bi₂O₂Te-SA: from continuous-wave mode-locking to dual-wavelength Q-switched modelocking

Q-switched mode-locking (QSML) can generate high-energy ultrashort pulses, attracting significant attention in areas such as high-precision measurement, laser micromachining, and biomedical applications. A saturable absorber (SA) based on a tapered optical fiber integrated withBi<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>Te nanosheets (Bi₂ O₂ Te-NSs) was fabricated, and a passively mode-locked erbium-doped fiber laser (PML-EDFL) with positive dispersion based on this SA was proposed. The passive continuous-wave mode-locking and QSML phenomena at the 1550 nm wavelength band were investigated. When the pump power was 51 mW, a dissipative soliton (DS) pulse with a duration of 60.8 ps was obtained. When the pump power reached 130 mW, a singlewavelength QSML was achieved. By incorporating 0.1 m of polarization-maintaining fiber (PMF), synchronized dualwavelength QSML was observed. The results not only demonstrate the considerable promise of Bi<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>Te-SA in PML-EDFLs, but also provide an alternative compact light source for optical communications, optical frequency comb, high-density optical storage, and related ultrafast photonics applications.