Multi-pulse dynamic patterns have been experimentally documented in a passively mode-locked (PML) erbium-doped fiber (EDF) laser using an Sb₂S₃-PVA saturable absorber (SA). The fundamental mode-locking operation, with a repetition rate of ∼3.22 MHz, a pulse width of ∼2.5 ps, a signal-to-noise ratio (SNR) of ∼50 dB and a peak power over 200 W, was achieved under a pump power from 280 to 360 mW with appropriate polarization states introduced by the polarization controllers (PCs). By rotating the orientation of the intra-cavity PCs carefully and slowly at a pump power of 350 mW, it was found that a multi-pulse bunch was transformed gradually from a single-pulse to a twelve-pulse bunch, with several intermediate transition states of multi-pulse bunches being observed. In addition, other characteristic modes including disordered multi-pulses and soliton rains have been experimentally observed by meticulously adjusting the polarization states of PCs at a pump power of 350 mW. Our systematic study clearly demonstrates that Sb₂S₃ has potential as an effective SA for generating different operation states of multi-pulses in PML anomalous-dispersion EDF lasers.

In this paper, tin diselenide ( $\text{SnSe}_2$ ) was successfully prepared with liquid phase exfoliation method and embedded into polyvinyl alcohol (PVA) as a saturable absorber (SA) in a dual-wavelength passively mode-locked Yb-doped fiber laser. Stable mode-locked pulses with a maximum average output power of 2.55 mW and a slope efficiency of 1.3% at the fundamental repetition rate of 333 kHz were achieved. By properly adjusting polarization state, four kinds of dual-wavelength fundamental frequency mode-locked pulses with peak wavelength intervals of 0.4, 1.0, 1.5 and 1.9 nm were obtained, and corresponding waveforms with different single pulse shapes were investigated in our work. A maximum signal to noise ratio (SNR) of 71.04 dB indicates that $\text{SnSe}_2$ is promising to serve as SA in passively mode-locked fiber lasers.

In this paper, antimony trisulfide (Sb₂S₃) was successfully prepared with the liquid phase exfoliation method and embedded into polyvinyl alcohol (PVA) as a saturable absorber (SA) in a passively mode-locked Er-doped fiber laser for the first time. Based on Sb₂S₃-PVA SA with a modulation depth of 4.0% and a saturable intensity of 1.545 GW/cm², a maximum average output power of 3.04 mW and maximum peak power of 325.6 W for the stable mode-locked pulses was achieved with slope a efficiency of 0.87% and maximum single pulse energy of 0.81 nJ at a repetition rate of 3.47 MHz under a pump power of 369 mW. A minimum pulse width value of 2.4 ps with a variation range less than 0.1 ps, and a maximum signal to noise ratio (SNR) of 54.3 dB indicated reliable stability of mode-locking, revealing promising potentials of Sb₂S₃ as a saturable absorber in ultrafast all-fiber lasers.

In this work, we report an all-fiber Nd-doped passively mode-locked fiber laser based on nonlinear polarization rotation mechanism operating in the 1.06 μ m region. When the pump power was 300 mW, a pulse with a maximum average output power of 0.63 mW, a narrowest pulse duration of 1.22 ps and a pulse repetition rate of 14.25 MHz was obtained.