提出了两种基于拍频技术的分别测量温度和旋光角的光纤光路结构方法, 利用错位光纤传感拍频实现了温度测量, 利用磁光光纤传感拍频实现了对旋光角的测量。拍频技术是一种不易受系统损耗和光源波动影响的光纤传感测量系统解调方案, 通过光纤光栅、掺铒光纤、错位光纤、磁光光纤和环形器组成光纤激光谐振腔产生激光拍频, 分析不同温度和不同磁场下输出的激光拍频变化量, 研究得到温度和旋光传感系统的性能。测温实验结果表明, 在温度从20℃变化到100℃的范围内, 拍频变化量的温度灵敏度为-39.125 kHz/℃, 拍频随温度升高而线性减小, 其线性拟合度为0.994 07。室温条件下电流为5 A时, 旋光测量输出拍频为13.375 MHz；同时仿真结果表明, 在旋光角变化为0°到90°范围内, 拍频变化量的旋光角灵敏度为1.77 MHz/°。研究证明, 基于错位光纤和旋光光纤的拍频测量结构用于光纤传感测量系统, 具有高分辨率, 高灵敏度, 低成本且性能稳定的优势。

Two methods that could measure temperature and optical rotation angle based on the technology of beat frequency were presented in this paper. The measurement of temperature was based on core offset optical fiber sensing method using the technology of beat frequency, while the measurement of optical rotation angle was based on the magneto optical fiber sensing method using the technology of beat frequency. The beat frequency method was a demodulation technique that would not be easily affected by the system loss and light source fluctuation. The light passed through the optical fiber grating, erbium-doped optical fiber, core offset optical fiber, magneto optical fiber and circulator, and then the beat frequency was produced. The variation of laser beat frequency at different temperatures and magnetic field conditions were studied and the performance of the temperature and magnetic sensing system were investigated. The experimental results with different temperatures range from 20℃ to 100℃ show that the beat frequency variation of the temperature sensitivity is -39.125 kHz/℃. Beat frequency decreases with the increase of temperature, and the linear fitting degree is 0.994 07. The interval of beat frequency is 13.375 MHz when the current is 5 A under room temperature. The simulation results show that the sensitivity of the beat frequency variation with the angle of rotation is 1.77 MHz/° when the rotation angle ranges from 0° to 90°. Therefore, the laser beat frequency methods based on the core offset fiber and magneto optical fiber are verified to have the advantages of high resolution, high sensitivity, high stability and low cost.