Mid-infrared supercontinuum generation of 1.14??W in a fluoroindate fiber pumped by a fast gain-switched and mode-locked thulium-doped fiber laser system

We report the generation of a spectrally flat supercontinuum in a fluoroindate (InF_3) fiber with a maximum time-averaged output power of 1.14 W and a spectrum extended to 4.75 µm. The pump source was a fast gain-switched and semiconductor saturable absorber mirror mode-locked thulium Tm-doped fiber laser followed by a cascade of two Tm-doped fiber amplifiers. The repetition rates of the gain-switched pulses and mode-locked sub-pulses were 50 kHz and 111 MHz, respectively, whereas the duration of sub-pulses recorded within a gain-switched pulse envelope was ∼110ps. This home-built pump laser system provided an output average power of 2.45 W at a central wavelength of 2 µm. To the best of our knowledge, this is the first paper on supercontinuum generation in an InF_3 fiber pumped by a fast gain-switched and mode-locked laser system. This approach is promising for further efficient continuum generation in the mid-infrared region.