8.76 W mid-infrared supercontinuum generation in a thulium doped fiber amplifier

A stable mid-infrared supercontinuum (SC) generation with a maximum average power of 8.76 W in a spectral band of 1.9-2.65 mu m is reported. To broaden the bandwidth of SC, a 1.55 mu m pulsed laser system delivering 1 ns pulses at a pulse repetition frequency of 500 kHz was used as a seed source for one-stage thulium-doped fiber amplifier. The power conversion efficiency for wavelengths longer than 2.4 mu m and 2.5 mu m was determined to be 28% and 18%, respectively, which is believed to be the most efficient power distribution towards the mid-infrared in SC sources based on Tm-doped fibers. The power spectral density of the continuum was calculated to be > 13 mW/nm with a potential of further scaling-up. A long-term power stability test, showing power fluctuations < 3%, proved the robustness and reliability of the developed SC source.