紧凑型光纤腔磁传感器研究与设计

Research and design of compact optical fiber cavity magnetic senseor

利用光学精密检测手段,结合高灵敏紧凑型光纤腔磁敏感单元,从理论和实验两方面研究了微弱磁信号敏感的传感系统。开发了紧凑型光纤腔磁敏感单元的制备工艺,长度为3 m的单模光纤紧凑绕制在直径为3 cm的超磁致伸缩材料Terfenol-D(Tb0.3Dy0.7Fe1.95)结构上。利用质量因子为1.9×10^(7)提升检测灵敏度,多圈绕制有利于外部磁扰动导致的光纤腔形变放大,而外部磁扰动导致Terfenol-D径向方向的伸缩,进而引起光纤腔长和共振频率的改变。实验结果表明,在158 mT的静磁增强下,直流磁场传感灵敏度为6.9 MHz/mT,交流磁场传感灵敏度为27.74 kHz/μT,系统本征噪声为623.298 nT/Hz1/2@100 kHz。所提出的磁传感方案,及制备的传感系统在微弱信号的测试领域具有广阔的应用前景。

In this paper,a weak magnetic signal sensing system is studied theoretically and experimentally by means of optical precision detection and highly sensitive compact fiber optic cavity magnetic sensing unit.The preparation process of compact fiber optic cavity magnetic sensitive unit is developed,and the single-mode fiber with length of 3 m is tightly wound on the structure of giant magnetostrictive material Terfenol-D(Tbo.3 Dyo.,Fei.95)with diameter of 3 cm.The quality factor of 1.9×10^(7)is used to improve the detection sensitivity.The multi-loop winding is beneficial to the optical fiber cavity deformation amplification caused by external magnetic disturbance,which leads to the expansion of the radial direction of Terfenol-D.The fiber cavity length and resonant frequency are changed.Experimental results show that under the magnetostatic enhancement of 158 mT,the sensitivity of DC magnetic field sensing is 6.9 MHz/mT,the sensitivity of AC magnetic field sensing is 27.74 kHz/μT,and the intrinsic noise of the system is 623.298 nT/Hz^(1/2)@1oo kHz.The magnetic sensing scheme proposed in this work and the sensor system prepared have broad application prospects in the field of weak signal measurement.