The analysis of gases by THz radiation offers a high degree of discrimination due to the narrow linewidths that are observed at low pressure. The sensitivity of existing high-resolution instruments is limited by the availability and performance of critical system components. This study uses two key components with physical structures at the wavelength scale to realise a high finesse THz cavity. The cavity is characterised and incorporated into a spectrometer. Sensitivity limits of the instrument are experimentally demonstrated for trace and pure gases. Both CEAS (Cavity Enhanced Absorption Spectroscopy) and CRDS (Cavity Ring-Down Spectroscopy) configurations are shown to give sub-ppm detection levels. The cavity has also been used to measure the atmospheric losses.

中文翻译：

---

腔辅助高分辨率太赫兹光谱仪

由于在低压下观察到的线宽较窄，太赫兹辐射对气体的分析具有高度的辨别力。现有高分辨率仪器的灵敏度受到关键系统组件的可用性和性能的限制。本研究使用两个具有波长尺度物理结构的关键组件来实现高精度太赫兹腔。对空腔进行表征并将其合并到光谱仪中。通过实验证明了仪器对痕量气体和纯气体的灵敏度限制。CEAS（腔增强吸收光谱）和 CRDS（腔衰荡光谱）配置均显示出亚 ppm 检测水平。该腔体还被用来测量大气损失。