Bonilla Manrique, Óscar ElíasPosada Román, Julio EnriqueGarcía Souto, José AntonioRuiz Llata, Marta2022-10-212022-10-212019-07-01Sensors 2019, 19(13), 2890, 14 p.1424-32101424-8220 (online)https://hdl.handle.net/10016/35915A sensitive optical microphone for photoacoustic spectroscopy based on the common path topology of a fibre laser Doppler vibrometer (FLDV) using phase-generated carrier demodulation and a slim diaphragm as an acoustic wave transducer was demonstrated. A resonant gas cell was adapted to enhance gas-detection performance and simultaneously provide efficient cancellation of the window background acoustic signal. Ammonia (NH3) was selected as the target gas. The absorption line was experimentally identified using a distributed feedback laser diode emitting at 1530 nm. The linearity and sensitivity of the gas sensor were measured using wavelength modulation spectroscopy with second harmonic detection. A Teflon diaphragm was used to implement the optical microphone, along with the FLDV, showing a minimum detectable pressure of 79.5 mu Pa/Hz(1/2). The noise-equivalent absorption sensitivity for NH3 detection at the absorption line at 1531.7 nm was 1.85 x 10(-8) W cm(-1) Hz(-1/2), and the limit of detection was 785 ppbv.14eng© 2019 by the authors. Licensee MDPI, Basel, SwitzerlandThis article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Atribución 3.0 EspañaPhotoacoustic spectroscopyGas detectionOptical microphoneResonant cellMembraneresearch articleElectrónicahttps://doi.org/10.3390/s19132890open access11314Sensors19AR/0000024346