Simultaneous bending-curvature and temperature measurements based on a fiber Bragg grating and a Mach–Zehnder interferometer

A design for simultaneous bending-curvature and temperature measurement using a fiber Bragg grating (FBG) inserted between two peanut-shaped structures is presented. The peanut-shaped structure is fabricated in the single-mode fiber by a fusion splicer and then connected with another peanut-shaped structure to form a Mach–Zehnder interferometer (MZI). By measuring the wavelength variation of the MZI and FBG in the spectral response of this configuration, simultaneous bending-curvature and temperature measurement is obtained. The experiment results show that curvature sensitivity is −27.58 nm / m ? 1 and FBG is 0.03869 and 0.01217 nm / ° C.