Tunable, High Pulse Energy and Narrow Linewidth Gas‐Filled Fiber Laser Across Near‐ and Mid‐Infrared

Widely tunable infrared fiber lasers that simultaneously deliver high pulse energies with narrow linewidths are critical for applications ranging from spectroscopy to nonlinear optics, yet achieving this combination has remained a long‐standing challenge. Here, we demonstrate that gas‐filled anti‐resonant hollow‐core fiber Raman laser offers tunability across a broad spectral range from the near‐infrared (∼1.4 µm) to the mid‐infrared (∼4.6 µm), with near microjoule level high pulse energy and a narrow linewidth of few gigahertz or less. This performance arises from a unique pump laser design together with an optimized selection of gas‐filled anti‐resonant hollow‐core fibers, opening a promising pathway toward compact, high‐performance tunable infrared fiber‐based sources.