Mid-infrared Spectral Intensity Enhanced Supercontinuum Generation Based on Nanosecond Thulium-Doped Fiber Laser.

We report a mid-infrared (MIR) spectral intensity-enhanced supercontinuum (SC) generation from a ZrF4-BaF 2-LaF3-AlF3-NaF fiber pumped by a nanosecond thulium-doped fiber laser. The spectral region covered from 1930 to 3500 nm with an average output power of 5.23 W. The average power ratio of the MIR SC for the wavelength > 2200 and > 2500 nm were 91.81% and 74.29% with respect to the total output power, respectively. The 1950-nm nanosecond seed pulses were generated from a long ring cavity based on semiconductor saturable absorber mode locker. The pulse repetition rate was 3.02 MHz with a tunable pulse duration of about 1.0 ns–3.9 ns. In addition, a 69.5-W short-wave infrared SC was obtained through a two-stage thulium-doped fiber amplifier with the spectrum extending from 1930 to 2500 nm. To the best of our knowledge, this is the first time such a spectral intensity-enhanced MIR SC directly pumped by a high-pulse-energy nanosecond thulium-doped fiber laser has been achieved. [ABSTRACT FROM PUBLISHER]