交/直流磁场相互增强的回音壁模式光学谐振腔磁场传感研究

As a new magnetic field sensing method, the magnetometer constructed by whispering gallery mode optical resonator and magnetostrictive material holds potential applications in the fields of national defense, medicine, geological exploration, intelligent transportation, and so forth. Recent studies of whispering gallery mode optical resonator based magnetometers mainly focus on AC magnetic field sensing, whose sensitivity is relatively low and the detection frequency is a little bit higher than that of practical needs. The relevant DC magnetic field sensing performance and temperature stability are still unknown, which greatly restricted the applications of the sensor. Regarding the above issues, a AC/DC field mutual reinforced sensing scheme is proposed to perform low frequency AC and DC magnetic field sensing with whispering gallery mode optical resonator in this project, in which DC (AC) magnetic field can be used to enhance the system's AC (DC) magnetic field detection capabilities. Furthermore, theoretical model is established to analyze the influence of structural properties, noise and temperature on its sensing performance. Therefore, the design principle and method is revealed so that the magnetometers with high sensitivity, low detection frequency and high temperature stability can be achieved. Additionally, those sensing systems are realized experimentally. The implementation of the project not only lay theoretical and experimental foundation for the development of magnetic field sensor with high-sensitivity, low-cost, low-power, and room-temperature working ability, but also provide new technical means for improving the temperature stability of magnetic field sensor.

回音壁模式光学谐振腔与磁致伸缩介质构成的磁场传感器作为一种新型磁场传感手段，在国防、医学、地质勘探、智能交通等领域中具有潜在应用前景。目前，该类传感器的研究主要以交流磁场传感为主，磁场探测频率略高、灵敏度略低，无法满足实际应用需求；且该类传感器的直流磁场传感性能与温度响应能力仍是未知的，限制了传感器的应用范围。针对上述问题，本项目提出交流与直流磁场相互增强的回音壁模式光学谐振腔低频与直流磁场传感方案，利用直流（交流）磁场增强系统的交流（直流）磁场探测能力。建立理论模型分析结构特性、噪声和温度等因素对磁场传感性能的影响，揭示高灵敏度、低探测频率、高温度稳定性的回音壁模式光学谐振腔磁场传感器的设计原则与方法，并进行实验验证。该项目的实施为推动高灵敏度、低成本、低功耗、室温工作的磁场传感器件的发展奠定理论与实验基础，也为提升磁场传感器件的温度稳定性提供新的技术手段。

基于回音壁模式光力谐振腔的磁场传感系统作为新兴的磁场测量手段，在医学、国防等领域具有潜在的应用价值。目前该类传感器的研究主要以交流磁场传感为主，且该类传感器的直流磁场传感性能与温度响应能力仍是未知的，限制了传感器的应用范围。该项目在实施过程中，提出了低成本的毛细管光力谐振腔磁场传感单元的加工方法，同时具有较高的光学品质因数，并在实验上验证了该传感单元能够进行直流磁场/交流磁场互增强的交流与直流磁场传感。进一步地，通过系统优化在实验上实现了温度稳定性较好的交流磁场传感系统，也同时获得了温度稳定性较好、交流磁场解调的直流磁场传感系统。实验结果表明：在直流磁场提升交流磁场灵敏度方面，通过额外引入直流磁场，对于填充Fe-Ga和Terfenol-D的光学谐振腔交流磁场传感系统，其最佳灵敏度可分别提升7.18倍和5.17倍；在交流磁场辅助直流磁场测量方面，基于Terfenol-D材料的磁场传感单元在频率为118kHz的交流磁场信号辅助下获得了1.26dB/mT的直流磁场传感灵敏度；基于Fe-Ga材料的磁场传感单元在579kHz交流磁场信号的调制下获得了2.06dB/mT的直流磁场传感灵敏度，较填充Terfenol-D材料的磁场传感结构解调直流磁场的灵敏度提升了0.6倍，且二者相比采用谱线漂移方式的光纤磁场传感单元的直流磁场传感灵敏度均有显著提升；最后，通过封装的方式提升了传感单元的温度稳定性和结构稳定性，获得了在[-11~50] ℃的宽温区内温度稳定性较好的交直流磁场传感系统。