Parallel sensing of multiple greenhouse gases adopting a mid-infrared dual-comb spectrometer with 300,000 comb-tooth-resolved frequency components

Mid-infrared (MIR) spectroscopy is instrumental in addressing gas molecule-related environmental and ecological challenges. Especially, massively parallel sensing capability is critical to multi-species molecules analysis, enabling the demands for various MIR gas characterizations. However, real-time, high-accuracy parallel sensing for multiple gases remains a significant challenge due to the limitations in laser bandwidth and sampling speed. Here, we present a broadband MIR dual-comb spectrometer for the simultaneous detection of multiple greenhouse gases. This MIR spectrometer employs a scheme of difference frequency generation (DFG), directly producing a wide spectrum spanning 3.2–4.7 μm with over 300,000 comb-tooth-resolved frequency lines at a 100 MHz resolution. In addition, we demonstrated the parallel detection of four mixed gas molecules (CH₄, C₂H₂, CO, and N₂O), in which the absorptions were in excellent agreement with HITRAN database. This broadband MIR dual-comb spectrometer is promising to be integrated with only fiber devices and periodically poled lithium niobate waveguides, providing a high-precision, high-efficiency approach for massively parallel sensing in atmospheric or industrial monitoring.