提出了一种基于双偏置结构光纤马赫-曾德干涉仪(Mach-Zehnder interferometer,MZI)的超高灵敏度折射率传感器,理论分析了偏置型MZI的干涉机理。通过光束传播法(beam propagation method,BPM)模拟分析了多模态偏置光纤的折射率传感特性、以及在不同偏置长度和折射率 范围内折射率灵敏度的变化,对比了单偏置与双偏置的传感特性。仿真结果表明,在折射率为1.333 0—1.334 0的范围内,单偏置MZI的折射率灵敏度为-5 557 nm/RIU,而双偏置MZI的折射率灵敏度为-14 071 nm/RIU,该结果为实现高灵敏度液体折射率测量提供了重要理论依据。该传感器结构紧凑,整体长度只有1 200 μm,在液体折射率测量领域具有重要的应用价值。

An ultra-high sensitivity refractive index sensor based on double biased fiber Mach-Zehnder interferometer (MZI) is proposed.The interference mechanism of biased MZI is analyzed theoretically.The refractive index sensing characteristics of the multimodal biased fiber,the variation of refractive index sensitivity in different biased lengths and refractive index ranges are simulated and analyzed by beam propagation method (BPM),and the sensing characteristics of single-biased and double-biased are comparedThe simulation results show that the refractive index sensitivity of single-biased MZI is -5 557 nm/RIU when the refractive index range is 1.333 0—1.334 0,and the refractive index sensitivity of double-biased MZI is -14 071 nm/RIU,which provides a import theoretical basis for high sensitivity measurement of liquid refractive index.The sensor has a compact structure and the overall length is only 1 200 μm,which has important application value in the field of liquid refractive index measurement.

山东省重点研发计划项目(公益类) (2019GSF111011) 、 山东省自然科学基金面上项目(ZR2020MF109) 和山 东省重点研发计划(重大科技创新工程) (2020CXGC010204)资助项目