利用微纳光纤的倏逝场效应,提出一种布里渊折射率传感器。利用混合声波模式激发的多峰布里渊频谱结构,实现了液体的折射率传感测量。实验结果发现,在氯化钠溶液中,长2 μm的微纳光纤在10.4 GHz左右的布里渊信号峰具有较好的信噪比,且该布里渊信号峰频移在一定范围内随液体折射率呈线性变化,在折射率范围为1.3333~1.3612时折射率传感灵敏度为369.6 MHz/RIU(RIU为折射率单元)。该技术为折射率传感提供了新的思路和方案。

This study proposes a Brillouin refractive index sensor based on the evanescent field effect of a micro-nano fiber. Multipeak Brillouin spectrum caused by hybrid acoustic field of the fiber is used for liquid refractive index sensing. Experimental results show that, for a 2 μm-micro-nano fiber, Brillouin peaks at approximately 10.4 GHz have a relatively high signal-to-noise ratio in NaCl solution, and their frequency shifts have a linear dependence on the liquid refractive index. A refractive index sensing sensitivity of 369.6 MHz/RIU (RIU is refractivity unit) is obtained within the range of 1.3333-1.3612. The proposed sensor will provide a new alternative for refractive index sensing.