Passively Q-switched fiber laser based on Sb2S3 saturable absorber

Q-switched laser is one of the important techniques to achieve high-energy laser pulses and greatly promotes the development and application of the field of optical engineering. With the modulation of cavity loss by optical switch in the laser cavity, the energy output by the laser is compressed into a pulse with a very short duration. For passively Q-switched lasers, saturable absorbers (SAs) with nonlinear saturable absorption are commonly used as optical switches. In recent years, 2D materials are used widely as SAs, such as topological insulators, black phosphorous, transition metal dichalcogenides and transition metal oxides. As one of the TMDs, the antimonous sulfide (Sb₂S₃) with smaller band gap as well as excellent nonlinear optical properties is a promising SA material. In this paper, we demonstrate a passively Q-switched erbium-doped fiber laser based on Sb₂S₃ SA, which could generate stable short pulses. By utilizing the Sb₂S₃ SA fabricated with optical deposition method, an all-fiber cavity is built. In the experiment, a stable Q-switched pulse trains with a repetition frequency of 30 kHz, a central wavelength of 1558.4 nm and a pulse width of 6.4 μs are obtained at a 980 nm pump power of 35 mW. The signal-to-noise ratio of radio-frequency spectrum at the fundamental frequency is about 50 dB, indicating the high stability of the Q-switched pulse. To the best of our knowledge, this is the first demonstration of Q-switched fiber laser based on Sb₂S₃ material, which could contribute as a new potential SA material for pulsed fiber lasers.