Broadband saturable absorption of multilayer MoSSe alloy and its application in mid-infrared Q-switched fiber laser

•Broadband saturable absorption properties of the MoSSe alloy from near-infrared to mid-infrared waveband are demonstrated.•MoSSe alloy is demonstrated to be an excellent saturable absorber for the mid-infrared fiber laser for the first time.•This work reveals the potential of MoSSe alloy to be broadband photonic devices. MoSSe alloy, as a member of transition metal dichalcogenides family, exhibits exotic electronic and optical properties. Here, we demonstrate that MoSSe alloy possesses broadband saturable absorption properties from near-infrared to mid-infrared waveband. Using MoSSe alloy as a saturable absorber to modulate the Er3+-doped fluoride fiber laser, a stable Q-switching with the output pulse width as short as 390 ns at 2790 nm is achieved. This work reveals the potential of MoSSe alloy to be broadband photonic devices.