Elastic Fabry-Pyrot microcavity for high-sensitivity photoacoustic spectroscopy
Year: 2026
Authors: Chen Q.H., Wang Z., Pelini J., Dello Russo S., De Cumis M.S., De Natale P., Borri S., Ren W.
Autors Affiliation: Chinese Univ Hong Kong, Dept Mech & Automat Engn, Hong Kong, Peoples R China; CNR, INO Ist Nazl Ott, Via N Carrara 1, I-50019 Sesto Fiorentino, Italy; LENS, Via N Carrara 1, I-50019 Sesto Fiorentino, Italy; ASI Agenzia Spaziale Italiana, Ctr Geodesia Spaziale, I-75100 Matera, Italy.
Abstract: We report an elastic Fabry-P & eacute;rot microcavity (& micro;FP) acoustic transducer that combines mechanical compliance with resonantly enhanced optical interrogation, boosting the conversion of pressure-induced diaphragm displacement into an optical signal. The transducer comprises a high-reflectivity concave mirror fabricated on a fiber tip and a micro-electro-mechanical systems (MEMS) diaphragm, forming a microcavity of 80.7 & micro;m length. When interrogated at a probe wavelength near 1.55 & micro;m, the & micro;FP exhibits an optical quality factor of 7.55 & times; 104 and a mechanical resonance at 27 kHz. As a proof-of-concept demonstration, we integrate the & micro;FP transducer into a quantum cascade laser-based photoacoustic system operating near 10.5 & micro;m to analyze SF6 trace gas samples. The & micro;FP-based photoacoustic spectrometer achieves a 46 ppt minimum detection limit and a normalized noise-equivalent absorption (NNEA) coefficient of 1.6 & times; 10-9 cm-1 & sdot;W & sdot;Hz-1/2. The results establish resonant optomechanical microcavities as a new route to sensitive photoacoustic spectroscopy. (c) 2026 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.
Journal/Review: OPTICS LETTERS
Volume: 51 (18) Pages from: 5072 to: 5075
More Information: University Grants Committee (C4002-22Y) ; Innovation and Technology Commission (GHP/138/22); Shun Hing Education Charity Fund (RNE-p2-24); 1+1+1 CUHK-CUHK (SZ) -GDSTC Joint Collaboration Fund (2025A0505000079); National Natural Science Foundation of China (62305279); QOSTRAD (59182/2024) under the European Union-Next Generation EU (PNRR-MUR) PE000023-NQSTI; ASI-CNR Joint Project (2023-47-HH.0) ; Research Projects of Sigificant National Interest (PRIN) (QUAQK-2022KH2KMT).KeyWords: Quantum Cascade; SensorDOI: 10.1364/OL.604697
