Speaker
Description
Terahertz spectroscopy provides a powerful means of identifying gas-phase molecules through their characteristic spectral signatures. However, several technical hurdles still limit sensitive monitoring and high-frequency resolution, both of which are essential for distinguishing different gas species. While increasing the light-sample interaction length is beneficial, the relatively large beam size and divergence of terahertz radiation require a sizeable gas enclosure to substantially increase the interaction length. This configuration not only restricts the development of compact systems, but it also becomes a fundamental limitation for applications where only a small amount of the analyte gas is available.
In this work, we introduce a fibre-based terahertz gas spectroscopy platform that addresses these limitations by combining an anti-resonant hollow-core terahertz fibre with terahertz time-domain spectroscopy. We demonstrate a hollow core photonic crystal fibre that guides the terahertz field while simultaneously serving as a gas cell with an optimized geometry that minimizes the required sample volume. The fibre confines the radiation within its core by anti-resonant reflection, setting the effective interaction length between the field and the gas to 10 cm, which is the fibre length. The setup relies on broadband terahertz pulses generated through optical rectification in a GaP crystal and coupled into the fibre using free-space optics, while the transmitted THz field is detected by electro-optic sampling. This fibre-based architecture offers a compact alternative to conventional free-space gas cells while supporting broadband molecular spectroscopy. In brief, this work explores hollow-core terahertz fibres as a viable platform for THz gas spectroscopy, enabling applications ranging from toxic gas detection to non-invasive, breath-based diagnostics through waveguide-enhanced light-matter interaction.
| Keyword-1 | Gas spectroscopy |
|---|---|
| Keyword-2 | Terahertz fibres |