Micro-bending sensing based on single-mode fiber spliced multimode fiber Bragg grating structure

Fiber Bragg grating (FBG) is a commonly used optical fiber sensing structure. FBG bent sensors in multimode fiber have been achieved. However, the structure and manufacturing process are complex. In the present study, we designed a simple structure that composed of an ordinary single-mode fiber (SMF) and a section of multimode fiber (MMF) with a FBG. It can realize the dual-parameter sensing of micro-bending and temperature simultaneously. The experimental results suggested that the structure is sensitive to micro-bending and temperature, and the sensitivities do not interfere with each other. The temperature sensitivity is 13.4 pm/degrees C, and the maximum bending sensitivity is 23.03 dB/m(-1).