基于倾斜光纤光栅的温度不敏感振动传感器

提出了一种基于倾斜光纤光栅与多模光纤相结合的温度不敏感振动传感器，其振动传感头是在倾斜光纤光栅与单模光纤之间加入一小段多模光纤所组成。倾斜光纤光栅的反射光谱有布拉格模和包层模两部分组成，其中多模光纤的作用是将倾斜光纤光栅反射包层模耦合到单模光纤的基模。倾斜光纤光栅包层模对外界振动很敏感，通过传感器的包层模平均输出功率完成对外界振动物理量测量。由于采用强度解调的方式，可以大大降低传感器装置的复杂性。实验表明：当传感器温度从20 ℃上升到70 ℃时，传感器的输出平均光功率均方根误差为0.01 μW，其反射光谱平均输出功率影响很小，故可以避免外界温度对测量结果的影响。

Tilted Fiber Bragg Grating Based Temperature-Independent Vibration Sensor

A new type fiber vibration sensor based on a tilted fiber Bragg grating (TFBG) interacting with a multimode fiber (MMF) is presented. The sensing head is formed by inserting a small section of MMF into a sing-mode fiber and the TFBG. The reflection light from this titled fiber Bragg grating includes two parts, the reflected Bragg mode and cladding modes. The cladding modes are coupled back into core mode as a function of the multimode fiber. The power of the cladding modes is sensitive to the vibration, so the external vibration measurement can be obtained through the average output power of cladding mode. The sensor device is simple due to the usage of the intensity demodulation method. The experimental results show that the root mean square (RMS) detection error of the average power is 0.01 μW within the temperature range from 20 ℃ to 70 ℃, so it is proved to be temperature independent.