Magnetic field sensor and magnetic field tester

Abstract

The invention discloses a double thin-cladded long-period fiber grating intensity type magnetic field sensor based on magnetic liquid. The intensity type magnetic field sensor is characterized by consisting of double thin-cladded long-period fiber gratings and magnetic liquid. The invention further discloses a magnetic field tester for the double thin-cladded long-period fiber grating intensity type magnetic field sensor employing the magnetic liquid, comprising an LED light source, a 3dB optical coupler, a double thin-cladded long-period fiber grating intensity type magnetic field sensor employing the magnetic liquid, a photoelectric detector, and a data receiving and signal processing device. The double thin-cladded long-period fiber grating intensity type magnetic field sensor has the technical characteristics of small volume, simple system, excellent stability, safety, reliability, easiness in grid connection, and special advantage that the performance of the sensor can be designed according to actual requirements. Through the adoption of the magnetic field tester, the changes of a magnetic field can be detected on the basis of the changes in the light intensity of the senor under the effect of the magnetic field at a temperature between 0 DEG C and 80 DEG C, and the sensitivity is extremely high, while the measurement resolution of the magnetic field reaches 0.1 oersted in the range from 0 oersted to 1000 oersted.

Description

technical field [0001] The invention relates to an optical fiber sensing technology, in particular to a double-thin cladding long-period optical fiber grating intensity magnetic field sensor based on magnetic liquid and a magnetic field tester based on the sensor. Background technique [0002] Magnetic liquid is a stable colloidal system formed by nano-scale strong magnetic particles dispersed in the base liquid. It has both the magnetism of solid matter and the fluidity of liquid. It is a new type of functional material. Under the action of an external magnetic field, the magnetic liquid has a strong magneto-optical effect and is a new type of optical material. [0003] Long-period fiber grating is a very good transmission-type band-stop filter, which has the advantages of small additional loss, no back reflection, no electromagnetic interference, and full compatibility with optical fibers, making it widely used in optical fiber communications. The period of the long-perio...

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Problems solved by technology

[0004] In the prior art, S.Y.Yang et al. published "Origin and applications of magnetically tunable refractive index of magnetic fluid films" in "Applied Physics Letters" 2004, Vol. The characteristics of the change of the refractive index difference of the liquid film with the magnitude of the magnetic field are used for optical sensing research, but because the straight line is not obvious, the transmission loss is only 1.13%, so there is a lack of high precision.

[0005] In October 2008, Di Ziyun and others from Shanghai Jiaotong University applied for an invention patent application for "A device for detecting magnetic field changes based on changes in the refractive index of magnetic fluids". The publication number is CN 101281237A. The sensitivity of the device disclosed in this document has reached 0.0025nm / Gs, its working range can be from 0Gs to 1500Gs, but due to the need to use a spectrum analyzer to detect, the price is higher

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