Massively-parallel absorption peak calibration with broadband dual-comb spectrometer enables ultrahigh-precision Doppler velocimetry

Coherent laser spectroscopy enables non-intrusive measurements of the atmospheric airflow velocity via the utilization of the Doppler frequency shift of gas molecule absorption peaks. Crucial technologies for airflow velocity sensing, such as laser-induced fluorescence spectroscopy, coherent anti-Stokes Raman scattering spectroscopy, and tunable diode laser absorption spectroscopy, have attracted considerable attention owing to their respective advantages in sensitivity, resolution, and precision. However, simultaneously achieving high sensitivity, efficiency, and precision remains a major challenge, hindering the development of rapid high-accuracy airflow velocity sensing. Here, we develop a rapid ultrahigh-precision Doppler velocimeter based on broadband near-infrared dual-comb spectrometer with 46,300 comb-line-resolved frequency components. The high coherence and broad bandwidth of the dual-comb system enables the precise extraction of 78 acetylene absorption peaks across the P and R branches, with a maximum spectral signal-to-noise ratio of 1751.7. By applying weighted calculation model to these peaks, we determine the flow velocity to be 14.82 m/s with a measurement uncertainty of 0.03 m/s (corresponding accuracy: 0.23 %), which is an order-of-magnitude improvement over our previous result. This approach can be extended to the broader mid-infrared regions for enhanced sensitivity and precision, opening new avenues for applications such as rapid wind-finding radar, combustion propulsion system monitoring, and supersonic dynamics characterization.