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Concentration sensor based on a tilted fiber Bragg grating for anions monitoring

Melo, L. ; Rodrigues, J. ; Farinha, A. F. ; Marques, C. ; Bilro, L. ; Alberto, N. ; Tomé, J. P. ; Nogueira, R.N.

Optical Fiber Technology Vol. 20, Nº 4, pp. 422 - 427, May, 2014.

ISSN (print): 1095-9912
ISSN (online): 1068-5200

Journal Impact Factor: 1,300 (in 2014)

Digital Object Identifier: 10.1016/j.yofte.2014.05.002

Abstract
The ubiquity and importance of anions in many crucial roles accounts for the current high interest in the design and preparation of effective sensors for these species. Therefore, a tilted fiber Bragg grating sensor was fabricated to investigate individual detection of different anion concentrations in ethyl acetate, namely acetate, fluoride and chloride. The influence of the refractive index on the transmission spectrum of a tilted fiber Bragg grating was determined by developing a new demodulation method. This is based on the calculation of the standard deviation between the cladding modes of the transmission spectrum and its smoothing function. The standard deviation method was used to monitor concentrations of different anions. The sensor resolution obtained for the anion acetate, fluoride and chloride is 79 × 10−5 mol/dm3, 119 × 10−5 mol/dm3 and 78 × 10−5 mol/dm3, respectively, within the concentration range of (39–396) × 10−5 mol/dm3