Magnetic field sensor based on magnetic fluid and micro-nanofiber evanescent field

Abstract

The invention discloses a magnetic field sensor based on a magnetic fluid and a micro-nanofiber evanescent field. The magnetic field sensor comprises a laser light source, a single mode fiber, a magnetic fluid, a micro-nanofiber, a photoelectric detector and a mode coupling element formed on the basis of welding. The laser light source is connected with the micro-nanofiber immersed in the magnetic fluid through the single mode fiber, when light is transmitted along the micro-nanofiber, a large part of energy is transmitted in the form of the evanescent field, the micro-nanofiber enhances the interaction between an optical field and an external substance, the change of an external magnetic field changes the refractive index of the magnetic fluid in which the micro-nanofiber is immersed, i.e. the refractive index of the surrounding environment of the micro-nanofiber is changed, a part of light is continuously propagated through a fiber core, the other part of light is conducted on the interface of the micro-nanofiber and the magnetic fluid in the form of the evanescent field, and after entering the ordinary single mode fiber at the rear end, the other part of light is coupled into a cladding layer. After the two parts of light pass the mode coupling element which is formed on the basis of welding, the cladding layer mode is coupled to the fiber core, and is interfered with the residual fiber core mode, and the two parts of light finally enter the photoelectric detector. Magnetic field information can be modulated by detecting the strength of the light after interference.

Description

technical field [0001] The invention belongs to the field of optical fiber components and optical fiber sensing, in particular to a magnetic field sensor based on magnetic fluid and micro-nano optical fiber evanescent field. Background technique [0002] Magnetic field measurement is an important branch of electromagnetic measurement technology. Magnetic field measurement is involved in many fields of industrial production and scientific research. Such as: current measurement, magnetic prospecting, maglev train, geological exploration, isotope separation, mass spectrometer, electron beam and ion beam processing device, controlled thermonuclear reaction, and artificial earth satellite, etc., and even has applications in medicine and biology. For example, magnetic field therapy to treat diseases, use "magnetocardiogram" and "magnetoencephalogram" to diagnose diseases, the effect of environmental magnetic field on organisms and human body, and the research of magnetic phenomen...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to solve the problem of single structure and low sensitivity in the prior art. The present invention combines the optical characteristics of the micro-nano optical fiber evanescent field transmission and the tunable refractive index of the magnetic fluid, and proposes a method based on magnetic fluid and micro-nano Magnetic field sensor for optical fiber evanescent field

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