Temperature insensitive curvature sensor based on a combination interference structure and an intensity demodulation method

Abstract

ABSTRACTIn this article, a sensing head consisting of fiber loop mirror inscribed with a highly Birefringence photonic crystal fiber (HiBi‐PCF) was proposed and experimentally demonstrated. The fully collapsed air holes of the PCF at the spice regions allow the coupling of PCF core and cladding modes that makes a Mach–Zehnder interferometer. The couple efficiency of the core mode to the cladding mode will be decreased as the curvature on the HiBi‐PCF part is increased. The curvature variation on the HiBi‐PCF part can be obtained by detecting the fringe visibility of the interference patterns. Experimental results show that the curvature sensor with maximal sensitivity of 10.171 dB/m−1 within a measurement range of 0–0.48 m−1 is obtained. Owing to the low thermo‐optic and thermo‐expansion coefficient of the HiBi‐PCF and with the using of intensity demodulation method, the proposed sensor can overcome the temperature and curvature cross‐sensitivity effects. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:806–809, 2015