Fiber Bragg grating sensing multiplexing based on LP01 and LP11 spatial mode diversity

In this paper, we propose a fiber Bragg grating (FBG) multiplexing method based on mode diversity, which achieves FBG multiplexed sensing by utilizing spatial mode dimensionality. The mode diversity FBG multiplexing system based on few mode fiber (FMF) circulator and photonic lantern is constructed, and the LP₀₁ and LP₁₁ temperature sensing multiplexing are experimentally verified. The results show that the proposed technique is capable of achieving multichannel high-resolution temperature measurements, with temperature resolutions better than 0.5 °C for both LP₀₁ and LP₁₁ spatial modes, and detection sensitivities of 15.8 pm/ °C and 16.2 pm/ °C, respectively.