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

Zhen Wang; Qiang Wang; Hui Zhang; Simone Borri; Iacopo Galli; Angelo Sampaolo; Pietro Patimisco; Vincenzo Luigi Spagnolo; Paolo De Natale; Wei Ren

doi:10.1016/j.pacs.2022.100387

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

Photoacoustics. 2022 Jul 22:27:100387. doi: 10.1016/j.pacs.2022.100387. eCollection 2022 Sep.

Authors

Zhen Wang^{1

2}, Qiang Wang^{1

3}, Hui Zhang^{1

3}, Simone Borri⁴, Iacopo Galli⁴, Angelo Sampaolo⁵, Pietro Patimisco⁵, Vincenzo Luigi Spagnolo⁵, Paolo De Natale⁴, Wei Ren²

Affiliations

¹ State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
² Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, New Territories, Hong Kong, China.
³ University of Chinese Academy of Sciences, Beijing 100049, China.
⁴ CNR-INO - Istituto Nazionale di Ottica, and LENS - European Laboratory for Nonlinear Spectroscopy, 50019 Sesto Fiorentino, Italy.
⁵ PolySense Lab - Dipartimento Interateneo di Fisica, University and Politecnico of Bari, Via Amendola 173, Bari, Italy.

Abstract

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 × 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.

Keywords: Acoustic resonator; Gas sensing; Optical cavity; Photoacoustic spectroscopy; Quartz tuning fork; Ultra-high sensitivity; Ultra-wide dynamic range.