High-power supercontinuum generation in the mid-infrared pumped by a soliton self-frequency shifted source

We report the demonstration of a fiber-based supercontinuum source delivering up to 825 mW of average output power between 2.5 and 5.0 mu m generated in all-normal dispersion regime. The pumping source consists of an amplified ultrafast Er-3(+):ZrF4 fiber laser providing high peak power femtosecond pulses at 3.6 mu m with an average output power exceeding the watt-level. These pulses are spectrally broadened through self-phase modulation using commercial chalcogenide-based step-index fibers. Al2O3 anti-reflection coatings were sputtered on chalcogenide fiber tips to increase the launching efficiency from 54% to 82%, making this record output power possible, and thus confirming that such coatings can support watt-level pumping with intense femtosecond pulses. To the best of our knowledge, this result represents the highest average output power ever achieved from a As2Se3-based mid-112 supercontinuum source with the potential of a high degree of coherence. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement