Abstract. An optical fibre sensor for determination of acetic acid is presented. The sensing probe is based on a fibre Bragg grating (FBG) Fabry–Perot cavity, coated with a thin film of sol–gel–PVP (polyvinylpyrrolidone) composite material. The polymeric thin film renders the interferometric output sensitive to the presence of carboxylic acid species. Results show that the wavelength of the interferometric peaks changes with acetic acid concentration, enabling its quantification. Coupling the fibre probe with a serrodyne modulated readout interferometer enables pseudo-heterodyne interrogation and the detection of acetic acid with a sensitivity of 92.6 deg/% L/L and a resolution of 0.2% L/L. The results demonstrate the potential of the proposed scheme to operate as a sensitive chemical sensor platform.

Keywords: optical fibre sensor, fibre Fabry–Perot cavity, acetic acid sensor

Print publication: Issue 12 (December 2009)
Received 16 July 2009, in final form 25 September 2009
Published 29 October 2009