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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-39.125kHz/℃,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5A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 kinds of optical fiber optical path structures based on beat frequency technology were respectively proposed. The temperature measurement was realized by using offset optical fiber sensing beat frequency, and the rotation angle was measured by using the magneto-optical fiber sensing beat frequency. The beat frequency technique is a demodulation scheme of an optical fiber sensing measurement system which is not easily affected by system loss and light source fluctuation. A laser beat frequency is generated by a fiber laser cavity formed by a fiber grating, an erbium-doped fiber, a misalignment fiber, a magneto-optical fiber and a circulator , Analyzes the variation of laser beat frequency output at different temperatures and different magnetic fields, and studies the performance of temperature and optical rotation sensing system. The results of temperature measurement show that the temperature sensitivity of the beat variation is -39.125kHz / ℃ and the beat frequency decreases linearly with the increase of temperature in the range of temperature from 20 ℃ to 100 ℃, the linearity is 0.994 07. When the current is 5A at room temperature, the beat frequency of the optical rotation measurement is 13.375 MHz. The simulation results show that the sensitivity of the rotation angle of the beat variation is 1.77 MHz / ° when the rotation angle varies from 0 ° to 90 °. The research proves that the beat measurement structure based on the dislocation fiber and the optical fiber is used in optical fiber sensing measurement system, which has the advantages of high resolution, high sensitivity, low cost and stable performance.