Work

Highly Sensitive Detection Method of Gas Based on the Fabry–Pérot Cavity Using Terahertz Frequency-Domain Spectroscopy

Year: 2025

Type: article

Abstract: This study introduces a simple, sensitive, efficient, and low-cost gas detection method in the terahertz range. A mode-adjustable Fabry–Pérot cavity is proposed to enhance detection by tuning the cavity length to match the cavity’s resonant frequency with the gas absorption peak. Terahertz frequency domain spectroscopy (THz-FDS), offering MHz-level resolution, provides stronger applicability than other spectral systems. Carbon monoxide (CO) is used as the test gas, with its 465 GHz absorption peak validating the coupling enhancement. The experiment measures CO absorption spectra from 0.02 to 1.5 THz, achieving a detection limit of 7%. Using a vacuum cavity to eliminate water vapor interference, low concentrations are detected, with a mode number of m = 10 yielding a detection limit of 3500 ppm, 20 times better than previous results. The impact of different modes on coupling was analyzed, showing more effective coupling when the Q-value of the resonant peak closely matches that of the gas absorption peak. This method demonstrates high sensitivity and applicability for detecting low concentrations of toxic and harmful gases.

Source: Chemosensors

DOI: 10.3390/chemosensors13110394

Authors: Yubo Wu, Kanglong Chen, Ayesha Kosar Fahad, Lulu Han, Cunjun Ruan

Institution: Beihang University

Language: English

Topic: Spectroscopy and Laser Applications

Subfield: Spectroscopy

Field: Chemistry

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,413

Funders: National Natural Science Foundation of China, Tsinghua University