单长周期光栅迈克耳孙干涉仪特性研究

单长周期光栅迈克耳孙（Michelson）干涉仪是由尾纤端面蒸镀高反膜的单根长周期光纤光栅构成。入射光经长周期光栅后，部分被耦合到包层中传输。经过包层和纤芯传输的光信号经尾纤端面反射后，重新耦合回到长周期光栅中，在光栅区域形成干涉。通过理论计算分析了各种因素对其光谱响应的影响。从实验上得到了干涉光谱的谐振峰波长位移与光纤段温度变化成良好的线性关系，测得其温度系数为31．3pm／℃。表明这种结构可用于高温传感或作为波分复用滤波器。

A Michelson interferometer based on a single long-period fiber grating (LPFG) is presented. The input signal is partly coupled into the cladding of the fiber by LPFG, and the pigtail of the LPFG is coated with high reflection film (RF). Therefore, both of the transmitted optical signals in the core and cladding are coupled simultaneously back to the LPFG and interfere by the HR coating. The interference characteristics are analyzed theoretically. The fringe-shift of the interference spectrum shows good linear relationship to the temperature, which is measured to be 31.3 pm/℃ in the experiment. The proposed device is expected to serve a high temperature sensor, as well as WDM filter.