基于涡旋光纤(vortex fiber,VF)激发的柱矢量模式(cylindrical vector modes,CVMs)设计了迈克尔逊干涉仪传感器,并对轴向应变、温度和折射率传感特性进行了理论研究和实验验证.通过对VF施加一个微弯长周期光栅(microbend long period gratings,MLPG),激发一阶CVMs(TE01、HE21和TM01);在VF尾端加反射镜,反射后纤芯中的基本模式HE11与环芯中的CVMs产生干涉,构成了迈克尔逊干涉仪.实验测得对应于柱矢量模式TM01、HE21和TE01的应变灵敏度分别为-1.01 nm/me、-1.61 nm/me 和-2.31 nm/me,温度灵敏度分别为 9.3 pm/℃,3.4 pm/℃和-2.4 pm/℃,而折射率不敏感.该传感器结构简单,且TE01模式具有最高应变灵敏度和最低温度灵敏度,可作为折射率不敏感的、温度交叉灵敏度低的理想无补偿应变传感器,是智能型工程结构中下一代传感器的理想选择.
Cylindrical vector modes based Michelson interferometer with vor-tex fiber for sensing applications
Michelson interferometer sensor based on cylindrical vector modes(CVMs)in a vortex fiber(VF)has been proposed and demonstrated.The sensing characteristics of axial strain,temperature,and refractive index have been studied using theoretical and experimental methods.By applying a microbend long period grating(MLPG)to the VF,the first-order CVMs of TE01,HE21 and TM01 modes are excit-ed.The end of the VF is equipped with a mirror,which interferes with the fundamental mode HE11 in the fiber core and the CVMs in the ring core after reflection,constructing an in-fiber Michelson interferome-ter sensor.The sensor exhibits the strain sensitivity of-1.01 nm/me,-1.61 nm/me,-2.31 nm/me and the temperature sensitivity of 9.3 pm/℃,3.4 pm/℃,-2.4 pm/℃ for the CVMs of TM0i,HE21 and TE01 respectively.But it is insensitive to refractive index.The sensor has a simple structure.The TE01 mode has the highest strain sensitivity and the lowest temperature sensitivity.It can be used as an ideal uncompensated strain sensor with insensitive refractive index and low temperature cross sensi-tivity.It has potential application of the next-generation sensors in smart engineering structures.
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