In-line fiber Mach-Zehnder interferometer combining with fiber Bragg grating for simultaneous curvature and temperature measurement

Abstract

A sensor head consisting of a photonic crystal fiber (PCF)-based Mach-Zehnder interferometer (MZI) and a fiber Bragg grating (FBG) is proposed and experimentally demonstrated for simultaneous measurement of curvature and temperature. The MZI fabricated by splicing a short length of PCF between two single-mode fibers with the air-holes structure completely collapsed near the splicing points, is sensitive to fiber bending and surrounding temperature, while the FBG is only sensitive to the later. Simultaneous measurement of curvature and temperature is therefore obtained. Sensitivities of 4.06 nm/m^-1 and 6.30 pm/°C are achieved experimentally for curvature and temperature, respectively. And the corresponding resolutions are 5.2x10^-4 m^-1 and 1.25 °C for curvature and temperature, respectively, based on the wavelength measurement resolution of 10 pm.