Quasi distributed optical fiber refractive index sensor using TiO2 film enhance fresnel reflection

This paper is mainly concerned with a quasi distributed optical fiber refractive index (RI) sensing system. A titanium dioxide (TiO2) thin film was coated on the cleaved end of a fiber to enhance the Fresnel reflection and the signal to noise ratio (SNR) of the RI sensor. The experiment setup is a quasi distributed sensor which includes three sensing point and a reference point. The reference point was used to eliminate the power fluctuation of the laser source, thus became one of the advantages with respect to other sensors. This sensing system was verified by testing the RI of different concentration of sucrose solutions. The experimental result shows that as the RI increasing in the range of 1.333–1.425, the relative reflection is decreasing with its sensitivity 1.69, 1.06 and 1.53, respectively.