基于长周期光纤光栅的磁场传感方案的实现

Realization of long period fiber grating based on magnetic field sensing scheme

长周期光纤光栅是近几年出现的一种新型光纤器件。其耦合机理是前向传输的纤芯基模与前向传输的各阶包层模式之间的耦合 ,这与光纤布喇格光栅明显不同。它对温度、应力、弯曲及外部折射率的变化具有相当高的灵敏度 ,是一种理想的光纤型敏感结构。提出利用长周期光纤光栅谐振波长的移动或移动变化量进行磁场强度的测量 ,并进行了理论推导、仿真实验及分析研究。得出了谐振波长变化量与外界磁场强度的关系模型。分析了设计中应该考虑的因素。

Long Period Fiber Grating (LPFG) is a novel optical fiber element arisen in recent years. Obviously different with Fiber Bragg Grating, the coupling of LPFG is between forward-propagating core fundamental modes and forward-propagating cladding modes. It has high sensibility to temperature, strain, bend and external refractive index and is an ideal optical fiber sensing structure. A method is proposed by calculating the value of wavelength or wavelength shift of LPFG to measure magnetic field intensity. Simulations, experiments and analysis are carried out after theoretical inference. Relationship modal of resonant wavelength shift and external magnetic field intensity is concluded. Effect of non-ideal factors in design is analyzed.