Design Of Microfiber Magnetic Field Sensor Based On Magnetic Fluid

Integration,miniaturization and high performance is the direction and requirements of sensor development in new era.Comparing to traditional sensors,optical fiber sensors have comparative advantages including anti-electromagnetic interference,high sensitivity,small size and so on.Therefore,it becomes the best solution to replace the traditional sensors.Optical fiber magnetic field sensor broke through the limitation of electromagnetic interference and show tremendous development potential in the field of magnetic field detection.Microfiber has superior optical sensing properties compared to the traditional fiber.With the manufacture technology of fiber rapidly develop these years,microfiber has obtained high favour of the researchers with its special micro-nano structure.In this paper,a fiber-optic magnetic field sensing system based on magnetic fluid and microfiber has been proposed.The detailed works include:1.The optical properties of the magnetic fluid and the basic characteristics,the sensing principle of microfiber are studied in detail.The mode field characteristics of cylindrical and tapered microfiber were simulated and analyzed.And the evanescent field(EF)distribution was obtained,which provides a theoretical basis for microfiber sensing based on evanescent field principle.2.In this article,a magnetic sensing structure based on microfiber and magnetic fluid has been designed on the basis of theoretical research.The microfiber sensor was fabricated using chemical corrosion method.A laboratorial platform was built by adopting the straight-through optical path where the magnetic fluid was used as the evanescent field medium.The experiment obtained a sensitivity of 0.02?W/m T.3.Based on the development demand of fiber magnetic field sensor,the fiber loop ring-down spectroscopy(FLRDS)was introduced into the EF-based fiber sensor.Then a fiber magnetic field sensor system with high sensitivity even resistance to the light source was achieved.The experimental optical path was optimized by theoretical analysis in the course of experiment.Finally,a stable fiber magneticsensing system with sensitivity of of 95.5ns/m T was realized.This paper provides a high sensitivity and high stability fiber-optic magnetic field sensing scheme based on the theoretical research and experimental verification.It provides a new reference to improve the sensitivity and stability of the optical fiber magnetic field sensor.