Record power and efficient mid-infrared supercontinuum generation in germania fiber with high stability

We report the demonstration of a mid-infrared (MIR) supercontinuum (SC) laser delivering a record-breaking average output power of more than 40 W with a long-wavelength edge up to 3.5 mu m. The all-fiberized configuration was composed of a thulium-doped fiber amplifier system emitting a broadband spectrum covering 1.9-2.6 mu m with pulse repetition rate of 3 MHz, and a short piece of germania fiber. A 41.9 W MIR SC with a whole spectrum of 1.9-3.5 mu m was generated in a piece of 0.2-m-long germania fiber, with a power conversion efficiency of 71.4%. For an even shorter germania fiber (0.1 m), an SC with even higher output power of 44.9 W (corresponding to a conversion efficiency of 76.5%) was obtained, but the energy conversion toward the long-wavelength region was slightly limited. A continuous operation for 1 hour with output power of 32.6 W showed outstanding power stability (root mean square 0.17%) of the obtained SC laser. To the best of the authors' knowledge, for the first time, this work demonstrates the feasibility of germania fiber on generating a 40-W level MIR SC with high efficiency and excellent power stability, paving the way to real applications requiring high power and high reliability of MIR SC lasers.

Automated summary

This study demonstrates a mid-infrared supercontinuum laser with a record-breaking average output power of over 40W, high efficiency, and excellent power stability. By using a thulium-doped fiber amplifier system and germania fiber, a broadband spectrum covering 1.9-3.5 micrometers wavelength range can be generated.