All-fiber-structure high-power mid-infrared gas-filled hollow-core-fiber amplified spontaneous emission source

Hollow-core-fiber (HCF) gas lasers (GLs) have garnered significant interest as a novel approach for generating mid-infrared lasers, owing to their inherent benefits of rich emission wavelength, high beam quality, and high output power potential. However, they are mostly achieved by a free-space coupling structure, which has a major drawback of being prone to vibrations and other environmental variations. Here, we devise and implement an all-fiber-structure gas-filled HCF amplified spontaneous emission (ASE) source at 3.1 μm based on the reverse tapering and angle-cleaved fusion splicing techniques. By optimizing the C 2 H 2 gas pressure, a maximum mid-infrared output power of 6.59 W was obtained, corresponding to a slope efficiency of 19.74% and near-diffraction-limited beam qualities of M x 2 =1.03 and M y 2 =1.06. Furthermore, with a similar all-fiber configuration, a CO 2 -filled HCF ASE source at 4.3 μm with output power exceeding 1.4 W was generated. To the best of our knowledge, the proposed all-fiber-structure HCF gas light source demonstrates the longest wavelength and highest power reported to date. The development of mid-infrared HCF gas light sources in an all-fiber configuration represents a significant step toward miniaturized HCF lasers, which hold promise as powerful new tools for application in laser medicine, space communication, and other scientific research.