Simultaneous Measurement of Temperature and Curvature Based on Hollow Annular Core Fiber

We propose a simultaneous temperature and curvature sensor based on a hollow annular core fiber (HACF) Mach-Zehnder interferometer (MZI). The MZI is fabricated by inserting a short section of HACF between two short pieces of multimode fibers, and interference occurs between the light beams transmitting along the air hole and annular core of the HACF. Curvature and temperature can be measured through fringe visibility variation and wavelength shift of the interference spectrum, respectively. The experimental results show that the temperature sensitivity is 30 pm/°C in the range of 30°C-100°C, and the maximum visibility variation is 32.4 dB from 0.555 to 5.405 m
^-1
. In addition, the device is insensitive to external refractive index.