Theoretical study of an evanescent optical integrated sensor for multipurpose detection of gases and liquids in the Mid-Infrared
| Type | Article | ||||||||||||
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| Date | 2017-04 | ||||||||||||
| Language | English | ||||||||||||
| Author(s) | Gutierrez-Arroyo Aldo1, Baudet Emeline2, Bodiou Loic1, Nazabal Virginie2, Rinnert Emmanuel 3, Michel Karine4, Bureau Bruno2, Colas Florent3, Charrier Joel1 |
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| Affiliation(s) | 1 : FOTON, UMR CNRS 6082, ENSSAT, BP80518, F-22305 Lannion, France. 2 : ISCR, UMR CNRS 6226, Glass & Ceram Team, F-35042 Rennes, France. 3 : IFREMER, Detect Sensors & Measurements Lab, Technol Res & Dev Dept, F-29280 Plouzane, France. 4 : Bur Rech Geol & Minieres, 3 Av C Guillemin, F-45060 Orleans 2, France. |
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| Source | Sensors And Actuators B-chemical (0925-4005) (Elsevier Science Sa), 2017-04 , Vol. 242 , P. 842-848 | ||||||||||||
| DOI | 10.1016/j.snb.2016.09.174 | ||||||||||||
| WOS© Times Cited | 47 | ||||||||||||
| Keyword(s) | Mid-Infrared detection, Optical integrated sensor, Evanescent optical field, Gas detection, Liquid detection | ||||||||||||
| Abstract | A theoretical study of evanescent optical sensor for multipurpose detection in the Mid-Infrared of gases and pollutants in water is presented in this paper. The opto-geometrical parameters of the transducers – ridge waveguides – have been optimized in order to obtain the highest evanescent power factor for monomodal propagation in the Mid-Infrared. The highest sensitivity has been obtained for a configuration with an optimal length of waveguide Lopt = 4.3 cm for intrinsic propagation loss equal to 1 dB/cm. Then a spiral waveguide configuration is suggested to obtain this optical length path in a monolithic structure. A numerical example is also included using a ridge waveguide based on chalcogenide glasses (GeSbSe). In case of gas detection, a generic calculation of the minima concentrations to be detected as a function of the molar absorption for any working wavelength is presented. Extremely low limits of detection can be achieved due to the strong absorption coefficients of gases and chemical species in the Mid-Infrared spectral range, 268 ppb in case of carbon dioxide at λ = 4.3 μm, 1.848 ppm and 781 ppb for methane at λ = 3.31 μm and at λ = 7.66 μm respectively. For the pollutants detection in water, an improvement of the integrated structure has been proposed to avoid water absorption in this spectral region by deposing a polymer (PIB) as waveguide superstrate, thus the limit of detection for toluene is 26 ppb at λ = 6.68 μm. These concentration minima that could be detected by the Mid-IR sensor are lower than the threshold limit values determined in the international environmental and health standards. Hence this integrated optical sensor may be considered as an attractive support tool in monitoring environmental and health fields. | ||||||||||||
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