Gain-switched dysprosium fiber laser tunable from 2.8 to 3.1 μm

We demonstrate a tunable gain-switched Dy³⁺-doped ZBLAN fiber laser around 3 μm, for the first time, to the best of our knowledge. The pump source is a homemade actively Q-switched Yb³⁺-doped silica fiber laser at 1.1 μm, yielding a repetition rate of 80 kHz and a pulse width of 300 ns. A plane-ruled grating in a Littrow configuration functions as the tuning element. At the launched pump power of 2.78 W, stable gain-switched pulses tunable within a ~300 nm range of 2800~3095 nm are achieved. When tuning the wavelength to 2946.5 nm, a maximum output power of 218.6 mW with a repetition rate of 80 kHz is obtained. The corresponding pulse width and energy are 530 ns and 2.73 μJ, respectively. The results imply that gain-switching of Dy³⁺-doped ZBLAN fiber laser is an alternative way for mid-infrared nanosecond pulse generation around 3 μm.