Mid-infrared (MIR) fiber lasers are crucial for various applications. While progress has been made using soft glass fibers, challenges remain in emission range and material robustness. Gas-filled hollow-core fibers (HCFs) offer a solution. This paper reports a 4.8-µm CO-filled silica-based HCF laser, enabled by a low-loss HCF (1.81 dB/m at 4.8 µm). A maximum output power of 46 mW and a tuning range of 180 nm (4644–4824 nm) were achieved using a 2.33-µm pump laser. This represents the longest wavelength silica-based fiber laser to date.

Xuanxi Li (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Linyong Yang (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Zhiyue Zhou (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Zhixian Li (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Hao Li (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Wenxi Pei (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Wei Huang (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Jing Shi (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Luohao Lei (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Meng Wang (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China), Zefeng Wang (College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China)