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.
