Photoacoustic dual-comb spectroscopy (DCS), converting spectral information in the optical frequency domain to the audio frequency domain via multi-heterodyne beating, enables background-free spectral measurements with high resolution and broad bandwidth. However, the detection sensitivity remains limited due to the low power of individual comb lines and the lack of broadband acoustic resonators. Here, we develop cavity-enhanced photoacoustic DCS, which overcomes these limitations by using a high-finesse optical cavity for the power amplification of dual-frequency combs and a broadband acoustic resonator with a flat-top frequency response. We demonstrate high-resolution spectroscopic measurements of trace amounts of C₂H₂, NH₃ and CO in the entire telecommunications C-band. The method shows a minimum detection limit of 0.6 ppb C₂H₂ at the measurement time of 100 s, corresponding to the noise equivalent absorption coefficient of 7 × 10⁻¹⁰cm⁻¹. The proposed cavity-enhanced photoacoustic DCS may open new avenues for ultrasensitive, high-resolution, and multi-species gas detection with widespread applications.

光声双梳光谱（DCS）通过多外差拍频将光频域中的光谱信息转换到音频域，从而实现高分辨率和宽带宽的无背景光谱测量。然而，由于各个梳状线的功率较低且缺乏宽带声谐振器，检测灵敏度仍然有限​​。在这里，我们开发了腔增强光声DCS，它通过使用高精度光学腔进行双频梳的功率放大和具有平顶频率响应的宽带声谐振器来克服这些限制。我们展示了整个电信 C 波段中痕量 C ₂ H ₂、NH ₃和 CO的高分辨率光谱测量。该方法显示在100秒的测量时间下的最小检测限为0.6ppb C ₂ H _{2 ，对应于7×10} ^-10 cm ^-1的噪声等效吸收系数。所提出的腔增强光声 DCS 可能为超灵敏、高分辨率和多物种气体检测开辟新途径，并具有广泛的应用。