Mid-infrared dual-comb spectroscopy has the potential to supplant conventional Fourier-transform spectroscopy in applications requiring high resolution, accuracy, signal-to-noise ratio and speed. Until now, mid-infrared dual-comb spectroscopy has been limited to narrow optical bandwidths or low signal-to-noise ratios. Using digital signal processing and broadband frequency conversion in waveguides, we demonstrate a mid-infrared dual-comb spectrometer covering 2.6 to 5.2 µm with comb-tooth resolution, sub-MHz frequency precision and accuracy, and a spectral signal-to-noise ratio as high as 6,500. As a demonstration, we measure the highly structured, broadband cross-section of propane from 2,840 to 3,040 cm⁻¹, the complex phase/amplitude spectra of carbonyl sulfide from 2,000 to 2,100 cm⁻¹, and of a methane, acetylene and ethane mixture from 2,860 to 3,400 cm⁻¹. The combination of broad bandwidth, comb-mode resolution and high brightness will enable accurate mid-infrared spectroscopy in precision laboratory experiments and non-laboratory applications including open-path atmospheric gas sensing, process monitoring and combustion.

在需要高分辨率，准确性，信噪比和速度的应用中，中红外双梳状光谱技术有可能取代传统的傅立叶变换光谱。到现在为止，中红外双梳子光谱法仅限于狭窄的光学带宽或低信噪比。使用波导中的数字信号处理和宽带频率转换，我们演示了涵盖2.6至5.2 µm的中红外双梳状光谱仪，具有梳齿分辨率，亚MHz频率精度和准确性，并且光谱信噪比为高达6,500。作为演示，我们测量了丙烷的高度结构化的宽带横截面，范围为2,840至3,040 cm ^-1，羰基硫的复数相/振幅光谱为2,000至2,100 cm ^-1，以及2,860至3,400 cm ^-1的甲烷，乙炔和乙烷的混合物。宽带宽，梳状模式分辨率和高亮度相结合，可在精密实验室实验和非实验室应用（包括开路大气气体传感，过程监控和燃烧）中实现准确的中红外光谱。