Passive Q-switching fiber laser based on MnS saturable absorber

In recent years, transition metal dichalcogenides (TMDs) have been widely used as saturable absorbers (SAs) in ultrafast fiber lasers. Among them, we have chosen manganese sulfide (MnS), also a type of TMD, for its small bandgap and excellent nonlinear optical properties. In this paper, we have fabricated a MnS thin film as a saturable absorber and demonstrated a passively Q-switched erbium-doped fiber laser based on MnS. It has achieved stable short-pulsed output. With a pump power of 29.8 mW from a 980 nm semiconductor laser, we obtained stable Q-switched pulses at a center wavelength of 1563.3 nm with a repetition rate of 29 kHz. The 3-dB spectral bandwidth is 1.25 nm, and the pulse width is 7.15 μs. The average output power is 0.95 mW, and the pulse energy is 32.8 nJ. The signal-to-noise ratio of the RF spectrum at the fundamental frequency is 54 dB, indicating the high stability of the Q-switched pulses. These results demonstrate that MnS, as a promising new SA material, provides a new research approach for generating stable short-pulsed output. Additionally, this is the first proposal of using MnS as a saturable absorber in Q-switched fiber lasers.