A compact optical magnetic field sensor based on a fiber laser oscillator circuit merged with a Sagnac loop that contains a polarization-maintaining fiber (PMF) and a magnetostrictive rod is proposed. The combination of the PMF-Sagnac loop and fiber laser oscillation circuit significantly increases the signal-to-noise ratio of the reflection spectrum in the system, which is a mixed spectrum that includes interference fringes and lasers. For the proposed system, an erbium-doped fiber amplifier is used to provide gain, a dispersion compensating fiber is used to compensate for dispersion in the system, a PMF is inserted in the Sagnac loop as a microwave filter, while a section of the PMF is bonded to a magnetostrictive rod to achieve magnetic field sensing. The proposed system is shown experimentally to produce a fine reflection interference spectrum. The highest intensity reflection interference peak (from the laser) is over 40 dB with a –3 dB line-width of about 0.03 nm. The system can provide magnetic field sensitivities of 0.07 nm/mT and 0.076 nm/mT for sensor head lengths of 1 m and 2 m, respectively, and exhibits a stability of ±0.029 nm over 1 h. The proposed sensing system has advantages of low cost, high sensitivity, compact structure, and can produce a fine and stable reflection spectrum.

中文翻译：

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基于光纤激光振荡电路与保偏光纤Sagnac干涉结构合并的磁场测量

提出了一种基于光纤激光振荡器电路的紧凑型光磁场传感器，该电路与包含偏振保持光纤（PMF）和磁致伸缩杆的Sagnac环路合并。PMF-Sagnac环路和光纤激光器振荡电路的组合可显着提高系统中反射光谱的信噪比，该系统是包括干涉条纹和激光器的混合光谱。对于建议的系统，使用掺do光纤放大器提供增益，使用色散补偿光纤补偿系统中的色散，将PMF插入Sagnac环路中作为微波滤波器，而将PMF的一部分磁致伸缩杆结合到磁致伸缩杆上以实现磁场感测。实验上显示了所提出的系统以产生精细的反射干涉光谱。（来自激光的）最高强度反射干扰峰超过40 dB，–3 dB的线宽约为0.03 nm。对于传感器头的长度分别为1 m和2 m，该系统可以提供0.07 nm / mT和0.076 nm / mT的磁场灵敏度，并且在1小时内具有±0.029 nm的稳定性。所提出的感测系统具有成本低，灵敏度高，结构紧凑的优点，并且可以产生精细且稳定的反射光谱。