Cavity and quartz enhanced photo-acoustic mid-IR sensor
Authors: Patimisco P., Borri S., Scamarcio G., Spagnolo V., Galli I., Giusfredi G., Mazzotti D., De Natale P.
Autors Affiliation: Rice University, Department of Electrical and Computer Engineering, 6100 Main Street, Houston, TX 77005, United States; Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, CNR-IFN UOS BARI, Via Amendola 173, Bari, Italy; Istituto Nazionale di Ottica (INO), CNR, European Laboratory for Non-linear Spectroscopy (LENS), Florence, Italy
Abstract: We report on a novel intracavity quartz enhanced photoacoustic (I-QEPAS) gas sensing technique taking advantage from both the high Q-factor of standard tuning forks and the power build-up of a high-finesse optical resonator. This first prototype employs a distributed feedback quantum cascade laser operating at 4.3 µm. CO2 has been selected as gas target. Preliminary results demonstrate an improved sensitivity, close to the cavity enhancement factor (~500) times the optical coupling efficiency (about 0.5), with respect to standard QEPAS technique. The detection limit was pulled from 7 ppm (obtained with standard QEPAS) down to 32 ppb, corresponding to normalized noise-equivalent absorption in the 10-9 W•cm -1•Hz-1/2 range.
Conference title: SPIE Photonics West 2014
Place: San Francisco, USA
KeyWords: Carbon dioxide; Chemical detection; Gas detectors; Nanophotonics; Quantum cascade lasers; Sensors, Cavity enhancement; Detection limits; Distributed feedback; Gas sensing; High Q factor; Intracavities; Optical cavities; Optical coupling efficiency, QuartzDOI: 10.1117/12.2042246