Multi-resonator photoacoustic spectroscopy

•A proof-of-concept of innovative multi-resonator photoacoustic spectroscopy (MR-PAS) technique was demonstrated.•A photoacoustic cell including three acoustic resonators operating at different resonant modes was designed, but only one microphone was used to listen the photoacoustic signal in each resonators.•This innovated technique offers multi-laser operation with a single photoacoustic spectrophone to simultaneously monitor multi-pollutant.•The MR-PAS would significantly reduce the size of multi-laser based PAS sensor for multi-pollutant analyses.

In this letter, we report on the development of an innovative multi-gas sensor based on multi-resonator photoacoustic spectroscopy (MR-PAS). This novel technique offers multi-laser operation to simultaneously monitor multiple pollutant species using a single photoacoustic spectrophone. A photoacoustic cell including three acoustic resonators operating at different resonant modes was designed, a single microphone was used to listen the photoacoustic signal in each resonator simultaneously. Feasibility and performance of the innovated MR-PAS sensor was demonstrated by simultaneous trace gas detection of H2O vapor, CH4 and CO2 using three near infrared distributed feedback diode lasers. 1σ normalized noise equivalent absorption coefficients (NNEA) of 2.1 × 10−9 cm−1 W/Hz1/2, 2.9 × 10−9 cm−1 W/Hz1/2 and 6.5 × 10−9 cm−1 W/Hz1/2 were respectively achieved for H2O, CH4 and CO2 detection at normal atmospheric pressure.