Curvature-Sensitivity-Enhanced Fiber-Optic Sensor Based on Bragg Hollow Core Fiber

We proposed a novel curvature-sensitivity-enhanced optical fiber sensor realized by Bragg hollow core fiber (BHCF). The suspended hollow core fiber (SHCF) and the BHCF were connected between two single-mode fibers forming the sensor. The special construction of a four-bilayer Bragg structure provides a well-defined period interference envelope in the transmission spectrum for sensing external perturbations. Because of the different sensitivities of the interference dips, the proposed BHCF-SHCF-based sensor is able to simultaneously measure the parameter of curvature and temperature by monitoring the intensity fluctuation and wavelength shift, respectively. The highest curvature sensitivity of the proposed sensor is measured to be 0.36 dB/m-1 in the range of 1.283-3.247 m-1 with the adjusted R square value of 0.9895. Besides, the experiment of the temperature is also conducted, the results indicate the two measurands without crosstalk attributing to the different demodulation method.