Passively Q-switched mid-infrared fluoride fiber laser around 3 µm using a tungsten disulfide (WS2) saturable absorber

In this letter, we demonstrate a passively Q-switched Ho3+/Pr3+ co-doped fluoride fiber laser centered at 2865.7 nm using a tungsten disulfide (WS2) saturable absorber (SA) for the first time, to the best of our knowledge. A multilayer WS2 film was fabricated using the sulfidation grown method and then transferred onto an Au mirror to act as the cavity feedback and SA device in a linear cavity. Under a launched pump power of 318.5 mW, stable Q-switched pulses with an average output power of 48.4 mW were achieved with a pulse duration of 1.73 µs and repetition rate of 131.6 kHz, resulting in a pulse energy of 0.37 µJ. Our experimental results confirm that WS2 can be an effective nonlinear modulator that is suitable for pulse generation at the 3 µm waveband.