Tb_(0.29)Dy_(0.71)Fe_(1.8)薄膜/光纤弱磁场探测性能研究

Weak-Magnetic-Field Detection Characteristic of Tb_(0.29)Dy_(0.71)Fe_(1.8) Thin Film/Optical Fiber

采用磁控溅射工艺,由计算机程序控制,在光纤表面制备了厚度均匀的Tb0.29Dy0.71Fe1.8超磁致伸缩薄膜。利用马赫-曾德尔干涉仪,对Tb0.29Dy0.71Fe1.8超磁致伸缩薄膜/光纤传感系统的磁探测性能进行了实验测试。结果表明:在调制频率1kHz附近,传感系统对磁场具有最大的信号响应;在恒定直流磁场及调制磁场强度小于1kA/m的条件下,系统输出信号大小随调制磁场强度线性增加,但调制磁场强度较大时会引起直流工作点的波动;在35～50kA/m的直流磁场范围内,系统输出信号随磁场强度的变化率较大,传感系统(对应1m长传感臂)可探测的最小磁场变化为8.6×10-2A/m,若采用分辨率为10-6rad.的干涉仪并增加镀膜光纤的长度和Tb0.29Dy0.71Fe1.8薄膜厚度,则可进一步提高系统的磁探测灵敏度。

Giant magnetostrictive Tb0.29Dy0.71Fe1.8 film/optical fiber composites with even thickness were prepared by magnetron sputtering process. A set of optical fiber magnetic field sensor by Mach-Zehnder interferometer was fabricated and tested using Mach-Zehnder interferometer, Results show that the sensor exhibits the largest responses against applied magnetic fields at the frequency of about lkHz. When the DC magnetic field is maintained at a fixed value, there is a good linearity between the output signal and the AC magnetic field which is below 1kA/m. Minimum detectable field of 8.6× 10^-2 A/m is demonstrated over 35 kA/m to 50 kA/m for the DC bias magnetic field for a 1-meter long fiber coated with Tb0.29Dy0.71Fe1.8 film.