Multi-resonator photoacoustic spectroscopy

Abstract 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 H 2 O vapor, CH 4 and CO 2 using three near infrared distributed feedback diode lasers. 1σ normalized noise equivalent absorption coefficients (NNEA) of 2.1 × 10 −9  cm −1  W/Hz 1/2 , 2.9 × 10 −9  cm −1  W/Hz 1/2 and 6.5 × 10 −9  cm −1  W/Hz 1/2 were respectively achieved for H 2 O, CH 4 and CO 2 detection at normal atmospheric pressure.