Doubly resonant sub-ppt photoacoustic gas detection with eight decades dynamic range

Photoacoustic spectroscopy (PAS) based gas sensors with high sensitivity, wide dynamic range, low cost, and small footprint are desirable in energy, environment, safety, and public health. However, most works have focused on either acoustic resonator to enhance acoustic wave or optical resonator to enhance optical wave. Herein, we develop a gas sensor based on doubly resonant PAS in which the acoustic and optical waves are simultaneously enhanced using combined optical and acoustic resonators in a centimeter-long configuration. Not only the lower detection limit is enhanced by the double standing waves, but also the upper detection limit is expanded due to the short resonators. As an example, we developed a sensor by detecting acetylene (C2H2), achieving a noise equivalent absorption of 5.7 x 10(-13) cm(-1) and a dynamic range of eight orders. Compared to the state-of-the-art PAS gas sensors, the developed sensor achieves a record sensitivity and dynamic range.

Automated summary

This study develops a gas sensor based on doubly resonant photoacoustic spectroscopy, which enhances both the acoustic and optical waves using combined optical and acoustic resonators. The sensor achieves high sensitivity and a wide dynamic range, making it capable of detecting low concentrations of gases.