Refractive index sensor using a Fabry-Perot cavity in polymer fiber

The possibility of using polymer fiber as a refractive index sensor is presented. The sensor is based on a Fabry-Perot interferometer formed at the tip of the polymer fiber. The interference is granted due to reflections between a fiber Bragg grating and the fiber end-face. The sensor was characterized to refractive index changes at constant temperature using a fast Fourier transform analysis of the interference signal. A sensitivity of −1.94 RIU
⁻¹
was achieved with a resolution of 1 × 10
⁻⁴
RIU and a cross sensitivity to temperature of 1× 10
⁻⁴
RIU/T.