Simultaneous measurement of curvature and temperature based on two waist-enlarged fiber tapers and a fiber Bragg grating

A fiber sensor scheme for simultaneous measurement of curvature and temperature is presented. The sensor head is formed by combining a fiber Bragg grating (FBG) with a all-fiber Mach-Zehnder interferometer (MZI), which is formed by cascading two waist-enlarged fiber tapers. The MZI is sensitive to curvature and surrounding temperature, while the FBG is only sensitive to the later. As a result, simultaneous measurement of curvature and temperature can be achieved by monitoring wavelength shifts of the MZI and the FBG. Sensitivities of 6.75 nm/m^-1 and 54.7 pm/°C are achieved experimentally for curvature and temperature measurements, respectively. This sensor has a compact configuration, because the FBG is inset into the MZI. Furthermore, the sensor also has the advantages of low-cost fabrication process and good physical strength.