【摘要】 介绍了一种基于多模干涉理论的光纤应变传感器,它由两段单模光纤中间夹一段多模光纤组成。我们利用光束传播法(BPM)对这种结构进行了数值模拟,获得了多模光纤中被激励的所有高阶模式的耦合效率的解析解,通过计算得到其应变灵敏度是FBG型应变传感器的2.14倍。随后,对这种新型传感器进行了应变传感实验,实验结果为1.92倍,计算值与实验值基本一致,证明了此种数值模拟方法适于研究此类光纤多模干涉问题,并体现出这种单模-多模-单模结构的传感器在灵敏度方面的优势。更多还原

【Abstract】 A optic-fiber strain sensor based on multimode interference(MMI) is presented.This strain sensor consists of 2 single-mode fibers(SMF)and a segment of multimode fiber(MMF) caught in the middle of the two SMFs.The analytical solution of the coupling coefficients among the modes excited in the MMF is simulated and obtained by using beam propagation method(BPM).The results show that the strain sensitivity of this structure is 2.14 times of Fiber Bragg Grating(FBG) strain sensor,which reasonably agree with an experimental result of 1.92.Our studies show that BPM is suitable for simulating the multimode-interference structure,and the SMF-MMF-SMF(SMS) structure is more sensitive than the FBG strain sensor.更多还原