Battery-powered portable optical frequency comb based on a NALM mode-locked fiber laser for open-path field use

We report the development of a portable optical frequency comb for open-path measurements, based on a polarization-maintaining nonlinear amplifying loop mirror fiber comb. The whole system can be operated outdoors using a single battery. The system delivers 140 mW of output power with a broadband near-infrared spectrum spanning 1100–2300 nm, enabling propagation over distances up to 80 m. Open-path measurements were demonstrated over a 40 m round-trip path, with the transmitted power and spectral coverage sufficient for spectroscopic analysis. Additionally, optical heterodyne signals were successfully measured under open-path conditions, confirming that the portable comb is suitable for a dual-comb setup.