美国国家标准与技术研究所Ye Jun研究小组取得新进展。他们提出了用于高度复杂气体传感的调制环衰梳干涉测量法。相关论文于2025年2月19日发表在《自然》杂志上。

研究人员表示，与健康和环境相关的气体样品通常包含许多分子种类，其浓度动态范围很大。高精细腔增强的中红外频率梳状光谱，已经实现了迄今为止最灵敏的多种微量气体探测。然而，该技术的性能主要取决于，确保在广谱覆盖范围内的吸收路径长度增强，如果存在强吸收化合物，则会受到梳腔频率不匹配的严重限制。

在这篇文章中，小组介绍了调制环衰梳干涉术，一种解决梳子腔增强应对腔内强吸收或色散的脆弱性的技术。该技术的工作原理是测量通过长度调制腔传输的，大量平行梳状线携带的衰荡动力学，充分利用场动力学的周期性和迈克尔逊干涉仪引入的多普勒频移。

作为演示，研究人员测量了高度分散的人类呼出气体样本和中红外环境空气，精细度提高到23000，覆盖范围提高到1010 cm^-1。这种精细度和光谱覆盖范围的产品，比之前的所有演示要优几个数量级，使他们能够同时量化20种不同的分子物种，灵敏度超过万亿分之一，浓度变化为7个数量级。

这项技术解锁了下一代复杂和动态分子组成的传感性能，并对精细度和光谱覆盖范围进行了可扩展的改进。

附：英文原文

Title: Modulated ringdown comb interferometry for sensing of highly complex gases

Author: Liang, Qizhong, Bisht, Apoorva, Scheck, Andrew, Schunemann, Peter G., Ye, Jun

Issue&Volume: 2025-02-19

Abstract: Gas samples relevant to health1,2,3 and the environment4,5,6 typically contain many molecular species that span a huge concentration dynamic range. Mid-infrared frequency comb spectroscopy with high-finesse cavity enhancement has allowed the most sensitive multispecies trace-gas detections so far2,7,8,9,10,11,12,13. However, the robust performance of this technique depends critically on ensuring absorption-path-length enhancement over a broad spectral coverage, which is severely limited by comb–cavity frequency mismatch if strongly absorbing compounds are present. Here we introduce modulated ringdown comb interferometry, a technique that resolves the vulnerability of comb–cavity enhancement to strong intracavity absorption or dispersion. This technique works by measuring ringdown dynamics carried by massively parallel comb lines transmitted through a length-modulated cavity, making use of both the periodicity of the field dynamics and the Doppler frequency shifts introduced from a Michelson interferometer. As a demonstration, we measure highly dispersive exhaled human breath samples and ambient air in the mid-infrared with finesse improved to 23,000 and coverage to 1,010cm1. Such a product of finesse and spectral coverage is orders of magnitude better than all previous demonstrations2,7,8,9,10,11,12,13,14,15,16,17,18,19,20, enabling us to simultaneously quantify 20 distinct molecular species at above 1-part-per-trillion sensitivity varying in concentrations by seven orders of magnitude. This technique unlocks next-generation sensing performance for complex and dynamic molecular compositions, with scalable improvement to both finesse and spectral coverage.

DOI: 10.1038/s41586-024-08534-2

Source: https://www.nature.com/articles/s41586-024-08534-2