A New Bamboo-Shaped Sensor for Curvature Measurement With Microstructured Fiber

In this letter, we propose a novel bamboo-shaped interference sensor based on multistage photonic-band gap microstructured fiber (PBG-MF) and single-mode fiber (SMF) to build the cascaded Fabry-Perot interferometer (FPI). Due to the honeycomb space inside the PBG-MF, a higher extinction ratio (ER) is obtained in the reflection spectrum of the interferometer, which is conducive to improving the detection limit (DL) and resolution of the sensor. The bending direction can be identified by the structure proposed in this letter. Maximum curvature sensitivity is 991 pm/m^-1 in the convex direction. Maximum curvature sensitivity is -1118 pm/m^-1 in the concave direction. The sensor has the advantages of small size, high sensitivity, and high package stability. It is particularly suitable for ultra-short distance curvature sensing, such as the joints of the human body.