Simultaneous measurement of curvature and temperature based on LP11 mode Bragg grating in seven-core fiber

A robust and compact fiber sensor for simultaneous measurement of curvature and temperature based on LP11 mode Bragg grating is proposed and demonstrated in this paper. The sensor is formed by splicing a short piece of seven-core fiber (SCF) with Bragg grating to single mode fiber (SMF). The Bragg grating is inscribed by UV light exposure, and mainly LP01 resonance peak and LP11 resonance peak are observed in the reflection spectrum. The experimental results show that the wavelength of the LP11 Bragg resonance is insensitive to curvature but the power is very sensitive to curvature. The curvature sensitivity is -7.27 dB/m(-1) with a linearity of 0.997 in the curvature range of 0-1 m(-1). The temperature characteristic shows that the Bragg resonance has almost the same sensitivity as the common fiber Bragg grating (FBG). The sensor is also available to be independent of the ambient refractive index(RI).