All-fiber magnetic field sensor

Abstract

The invention discloses an all-fiber magnetic field sensor. The sensor is composed of a broadband light source, a sensing head and a spectrometer, wherein two ends of one section of a photonic crystal fiber with magnetic fluid poured in are welded with a single-mode fiber to form the sensing head, one end is melted eccentrically, a Mach-Zehnder interferometer with single fiber embedded is formed, changes of phase differences among different modes are caused through changes of the reflection rate of the magnetic fluid in the photonic crystal fiber, spectral shift is thus caused, the shift amount of a wave crest/a wave trough is detected to demodulate magnetic field information, and measurement on the magnetic field is realized. The all-fiber magnetic field sensor is compact in structure, small in size, simple in manufacturing, stable and reliable in operation, high in sensitivity and low in cost.

Description

technical field [0001] The invention belongs to the field of optical fiber components and optical fiber sensing, in particular to an all-fiber type magnetic field sensor. Background technique [0002] Magnetic field measurement is of great significance to fields such as science, military affairs, and industrial applications. Traditional magnetic field sensors are mainly based on electrical testing principles, such as electromagnetic induction and Hall effect, but sensors as electrical measuring instruments are often susceptible to electromagnetic interference, easy to corrode, and cannot work in harsh environments. Therefore, optical magnetic field sensors are attracting more and more attention. As an intrinsically insulating material, optical fiber has unique advantages in magnetic field sensing. In addition to being immune to electromagnetic interference, it also has the advantages of small size, light weight, high precision, and easy to form distributed measurement. It c...

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Problems solved by technology

[0004] After searching the literature of the prior art, it is found that the invention patent with application number 201010112530.7 discloses a magnetic field sensor realized by the interaction between magnetic fluid fluid and fiber grating. In the capillary with magnetic fluid, the operation is more complicated and the integration is low; the invention patents with application numbers 201010194583.8 and 201110102799.1 disclose a magnetic field sensor based on the interaction between the magnetic fluid and the optical fiber Fabry–Perot cavity. The disadvantages of this scheme are Since the length of the Fabry–Perot cavity is generally on the order of microns, it requires a very precise manufacturing process, and it is generally not easy to coat the optical fiber, which increases the difficulty of the solution; the application numbers are 201010519861.2 and 201310186027.X The invention patent discloses a magnetic field sensor based on the interaction between magnetic fluid and micro-nano optical fiber / bare optical fiber. The disadvantage of this solution is that the micro-nano optical fiber is very fragile and has low integration; A magnetic field sensor based on magnetofluid-infused polarization-maintaining photonic crystal fiber. They obtained the interference spectrum by constructing a Sagnac ring. This scheme directly pours magnetic fluid into the photonic crystal fiber, which is a simple structure and high integration solution, but the disadvantage is that the introduction of 2×2 fiber couplers leads to unnecessary power loss, because the photonic crystal fiber itself will have a very large loss after being filled with magnetic fluid, and the introduction of the Sagnac ring structure will cause additional loss, making it difficult to detect

[0005] Most of the currently disclosed optical fiber magnetic field sensors based on magnetic fluid fluid require complex and precise manufacturing processes, and the low integration level leads to poor stability. Therefore, a magnetic field sensor that is simple to manufacture, highly integrated, and stable and reliable has become Technical problems to be solved urgently by those skilled in the art

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