Fiber-optic Fabry-Perot refractive-index tip sensor based on endlessly photonic crystal fiber

Abstract

We present a novel fiber-optic refractive-index (RI) sensor based on F-P interferometer, formed by splicing an endlessly photonic crystal fiber to a single-mode fiber. This type of RI sensor can be used to simultaneously measure RI and temperature by determination of its fringe visibility and cavity length change, respectively. The RI resolution is ~2x10^-5 in the linear range and the cavity-length-temperature sensitivity is 18.72nm/ C o from 20°C to 100°C. In addition, the RI measurement based on the fringe visibility with such a miniature in-line fiber-optic tip sensor is independent on temperature change, making it suitable for practical applications.