Photoacoustic spectroscopy detection based on complementary interdigital cantilever enhanced Fabry-Perot acoustic sensor

Photoacoustic spectroscopy (PAS) has been widely used for detecting trace gases, but enhancing sound pressure detection capability of the acoustic sensor is crucial for improving gas detection sensitivity of the PAS system. In this paper, a complementary interdigital (CID) cantilever Fabry-Perot (F-P) fiber optic acoustic sensor (FOAS) was developed. Experimental results demonstrated that the CID cantilever operated at its resonance frequency of 1010 Hz exhibited a high sensitivity of 923.7 nm/Pa, and exhibited a signal-to-noise ratio of 72.2 dB and a minimum detectable pressure of 16.4 μPa/Hz ^1/2 at 1 kHz. In the concentration range of 20 ppm to 100 ppm, the sensitivity of PAS to C₂H₂ gas was 3.02 pm/ppm and the detection limits of C₂H₂ in N₂ background was 30.17 ppb. This design employs highly sensitive cantilevers with tunable resonance, enhancing the gas detection sensitivity of the PAS system by leveraging resonant frequency matching and signal amplification.