Proc. of SPIE
2016
SnO2-MOF-Fabry-Pérot humidity optical sensor system based on Fast Fourier Transform technique
A. LÓPEZ ALDABA; D. LÓPEZ-TORRES; J. ASCORBE; S. ROTA-RODRIGO; C. ELOSUA;  M. LÓPEZ-AMO; F.J. ARREGUI; J.M. CORRES;  J.-L. AUGUSTE; R. JAMIER; P. ROY; 

Abstract

In this paper, a new sensor system for relative humidity measurements based on a SnO2 sputtering deposition on a  microstructured optical fiber (MOF) low-finesse Fabry-Pérot (FP) sensing head is presented and characterized. The interrogation of the sensing head is carried out by monitoring the Fast Fourier Transform phase variations of the FP interference frequency. This method islow-sensitive to signal amplitude variations and also avoids the necessity of tracking the evolution of peaks and valleys in the spectrum. The sensor is operated within a wide humidity range (20%–90% relative humidity) with a maximum sensitivity achieved of 0.14rad/%. The measurement method uses a commercial optical interrogator as the only active element, this compact solution allows real time analysis of the data.

EXPERIMENTAL SET-UP AND OPERATION PRINCIPLE

… The MOF-FP optical fiber core was used as the substrate in a DC-Sputter deposition process (Pulsed DC Sputtering System, Nadetech Innovations) with a partial pressure of argon of 6.75×10-2 mbar, intensity of 140 mA and voltage of 190 V.

Keywords: Photonic crystal fiber; Microstructured optical fiber; Fiber sensor; Humidity sensing; Fast Fourier Transform