Simultaneous Measurement of Curvature and Temperature Based on Asymmetrical FPI

We propose and demonstrate an asymmetrical Fabry-Perot interferometric (AFPI) fiber sensor for simultaneous measurement of the curvature and temperature. The AFPI fiber sensor is comprised of a low reflective fiber Bragg grating with narrow bandwidth and a no-core fiber with broadband Fresnel reflection. The extinction ratio measured in the experiment is defined as the difference between the amplitude of the maximum peak and its left adjacent dip, which is about 6 dB. With the variation of curvature and temperature, the maximum amplitude peak wavelength of the AFPI and the extinction ratio show different responses, thus the simultaneous measurement of curvature and temperature can be achieved. From the experimental results, sensitivities of the proposed sensor for the curvature and the temperature are about 9.57 dB/m
^-1
(ranging from 0.8844 to 1.0995 m
^-1
for the measured extinction ratio) and 10.2 pm/°C (ranging from 10 °C to 60 °C), respectively. Such fiber sensor is simple, low cost, and compact.