In integrated cavity output spectroscopy (ICOS), a long optical cavity is often required for suppressing mode structure, which, however, blocks its application for fabricating compact gas sensors requiring gas cells with the volume at milliliter level or less. In this paper, we demonstrate that low-cost free-running Fabry–Perot diode lasers have intrinsic capability for promoting suppression of cavity resonance due to the broad linewidth. The ICOS is performed, for the first time to our best knowledge, by using a short cavity of less than 1 cm with a cavity volume of only 4.7 cm3. By introduction of the scheme of correlation spectroscopy, the problem of laser mode competitions is resolved. A minimum detectable absorption of 8.7 × 10−5 Hz−1/2 (noise-equivalent absorption sensitivity of 3.3 × 10−7 cm−1 Hz−1/2) is achieved. The performance is suitable for applications in which both high sensitivity and small gas cell volume are required.

中文翻译：

---

使用亚厘米短光腔与自由运行的法布里-珀罗二极管激光器相结合的集成腔输出光谱

在集成腔输出光谱（ICOS）中，通常需要长光学腔来抑制模式结构，然而，这阻碍了其在制造需要体积为毫升或更少的气室的紧凑型气体传感器中的应用。在本文中，我们证明了低成本自激法布里-珀罗二极管激光器由于宽线宽而具有促进抑制腔共振的内在能力。据我们所知，ICOS 是第一次使用小于 1 cm 的短腔体，腔体体积仅为 4.7 cm3。通过引入相关光谱方案，解决了激光模式竞争的问题。实现了 8.7 × 10-5 Hz-1/2（3.3 × 10-7 cm-1 Hz-1/2 的噪声等效吸收灵敏度）的最小可检测吸收。