CN210427778U

CN210427778U - Double-core optical fiber magnetic field sensing probe

Info

Publication number: CN210427778U
Application number: CN201920743709.9U
Authority: CN
Inventors: 刘玉婵; 刘月明; 孔嘉浩
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2019-05-22
Filing date: 2019-05-22
Publication date: 2020-04-28
Anticipated expiration: 2029-05-22

Abstract

The utility model relates to a two-core optical fiber magnetic field sensing probe. The double-core optical fiber sensing probe comprises a laser light source (1), a coupling module (2), a double-core optical fiber sensing probe (3) and a detector (4), wherein the coupling module (2) comprises a first optical waveguide (2-1) and a second optical waveguide (2-2), the double-core optical fiber comprises a first fiber core (3-1), a second fiber core (3-2), a cladding (3-3), an engraved groove (3-4) filled with magnetic fluid and a reflecting film (3-5), the engraved groove (3-4) filled with the magnetic fluid is positioned on the upper end face of the double-core optical fiber, the reflecting film (3-5) is adhered on the upper end face of the double-core optical fiber, and the lower surface of the engraved groove (3-4) filled with the magnetic fluid form an F-P cavity structure, when a magnetic field exists, the refractive index of the magnetic fluid is changed, so that the equivalent cavity length of the F-P cavity, the measurement of the magnetic field can be achieved by a change in the output light.

Description

Double-core optical fiber magnetic field sensing probe

Technical Field

The utility model belongs to the technical field of the optical fiber sensing, in particular to two core optic fibre magnetic field sensing probe, its structure comprises laser light source, coupling module, two core optic fibre sensing probe, detector to realize the measurement in magnetic field.

Background

The magnetic sensor is a device for converting the change of the magnetic property of a sensitive element caused by external factors such as magnetic field, current, stress strain, temperature, light, etc. into an electric signal, and detecting the corresponding physical quantity in this way. Traditional magnetic field sensors, such as hall sensors, magnetoresistive sensors, fluxgate sensors, magnetic induction coil sensors and the like, are prone to electromagnetic interference, while optical fiber magnetic field sensors have the advantages of being small in size, light in weight, high in precision, strong in anti-electromagnetic interference capability, capable of performing remote measurement and the like. Different types of fiber sensors can be made based on different optical principles, such as fiber sensors based on the interference type principle, fiber sensors based on the FBG principle, etc. According to different application occasions, there are optical fiber sensors applied to different occasions, such as temperature type optical fiber sensors, refractive index sensors, stress strain measurement sensors, magnetic field sensors and the like. For the optical fiber sensor, in the current report, the application of the common single-core optical fiber, i.e. one cladding and one fiber core, to the single-core optical fiber is more, and although the single-core optical fiber can realize bidirectional transmission, the accuracy of the sensor is not high due to the signal crosstalk. The double-core optical fiber is an optical fiber containing two fiber cores in the same cladding, each fiber core is an optical waveguide, namely two single-core optical fibers are integrated in one double-core optical fiber, the problem of signal crosstalk does not exist, and the precision of the sensor is greatly improved.

The magnetic fluid is a novel nano functional material, has the liquidity of liquid and the magnetism of solid substances, and also has rich optical properties, such as magneto-optical effect and thermal lens effect. The magnetic fluid does not show any magnetism when being in a static state; when a magnetic field is applied, the refractive index of the magnetic fluid is changed along with the increase of the magnetic field intensity. Therefore, the magnetic field can be measured using the magneto-optical effect of the magnetic fluid. The double-core optical fiber and the magnetic fluid are combined, and the magneto-optical effect of the magnetic fluid is utilized to measure the magnetic field.

The double-core optical fiber magnetic field sensing probe consists of a double-core optical fiber and a magnetic fluid, and the optical path of the double-core optical fiber is simpler than that of a common single-core optical fiber. The utility model discloses an optic fibre magnetic field sensing probe that two core optic fibre and magnetic current body combined together realizes the measurement in magnetic field.

Disclosure of Invention

An object of the utility model is to provide a design of two core optic fibre magnetic field sensing probe can realize the measurement to magnetic field.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

the utility model discloses a laser light source (1), coupling module (2), two core fiber sensing probe (3), detector (4), characterized by: the coupling module (2) comprises a first optical waveguide (2-1) and a second optical waveguide (2-2), the double-core optical fiber comprises a first fiber core (3-1), a second fiber core (3-2), a cladding (3-3), a notch (3-4) filled with magnetic fluid and a reflecting film (3-5), the laser light source (1) is coupled with the lower end of the first optical waveguide (2-1), the upper end of the first optical waveguide (2-1) is coupled with the first fiber core (3-1), the second fiber core (3-2) is coupled with the upper end of the second optical waveguide (2-2), and the lower end of the second optical waveguide (2-2) is coupled with the detector (5), as shown in figure 1.

The coupling module (2) is 3mm long, 3mm wide and 2mm high.

The diameter of first optical waveguide (2-1) be 4um, the diameter of second optical waveguide (2-2) be 4um, 62.5um are apart from the upper end of first optical waveguide (2-1) and second optical waveguide (2-2), the lower extreme is apart from 1 mm.

The diameter of the double-core optical fiber cladding (3-3) is 125um, the diameter of the first fiber core (3-1) is 4um, the diameter of the second fiber core (3-2) is 4um, the interval between the two fiber cores is 62.5um, and the numerical aperture is 0.25.

The groove (3-4) filled with the magnetic fluid is formed by etching the upper end face of the double-core optical fiber by femtosecond laser, and is 80um long, 80um wide and 0.3um deep.

The reflecting film (3-5) is 0.2um thick, is adhered to the upper end face of the double-core optical fiber, and forms a whole with the notch groove (3-4) filled with the magnetic fluid, and the reflecting film is used as the upper reflecting surface and the lower surface of the notch groove to form an F-P cavity structure to play a role in sealing the magnetic fluid.

The utility model relates to a two-core optical fiber magnetic field sensing probe. The invention has the advantages of high measurement precision, simple manufacture, small volume and the like.

Drawings

Fig. 1 is a schematic structural view of a dual-core optical fiber magnetic field sensing probe according to the present invention;

fig. 2 is a top view of the dual-core optical fiber magnetic field sensing probe of the present invention.

Detailed Description

The following will further describe the embodiment of the present invention with reference to fig. 1.

The utility model discloses a can carry out a two core optic fibre magnetic field sensing probe that measures to magnetic field, the concrete implementation step is as follows:

the method comprises the following steps: optical fiber end face pretreatment

And (3) flattening the upper end face and the lower end face of the double-core optical fiber by using an optical fiber cutting machine, and cleaning the end faces of the optical fiber by using an ultrasonic cleaning machine.

Step two: preparation coupling module

The coupling module is prepared by utilizing a semiconductor micromachining process and consists of two optical waveguides, wherein the diameters of the two optical waveguides are the same and are 4um, the upper ends of the two optical waveguides are separated by 62.5um, and the lower ends of the two optical waveguides are separated by 1 mm. The coupling module is 3mm long, 3mm wide and 2mm high.

Step three: and welding the coupling module with the lower end surface of the double-core optical fiber.

Step four: grooving the upper end face of a dual-core optical fiber

Fixing the processed double-core optical fiber on a fixture, then placing the fixture on a three-dimensional platform to keep the horizontal direction still, adjusting the three-dimensional platform to enable femtosecond laser to be focused above the central axis of the double-core optical fiber through an optical lens, gradually adjusting the three-dimensional platform from the contact of a focal point to the optical fiber, gradually moving upwards to control the depth of an engraved groove, adjusting an optical lens diaphragm to control the size of the focal point after the femtosecond laser is focused, and controlling the width of the engraved groove.

Step five: injecting the magnetic fluid into the notch groove.

Step six: a layer of reflecting film with the thickness of 0.2um is adhered to the upper end face of the double-core optical fiber.

The utility model discloses the basic principle in measurement magnetic field does: the upper and lower surfaces of the notch groove are used as two reflecting surfaces to form an F-P cavity principle, and the depth of the groove is the cavity length of the F-P cavity. When a magnetic field exists, the refractive index of the magnetic fluid is changed, so that the equivalent cavity length of the F-P cavity is changed, and the measurement of the magnetic field can be realized through the change of output light.

Claims

1. The utility model provides a two core optical fiber magnetic field sensing probe, includes laser light source (1), coupling module (2), two core optical fiber sensing probe (3), detector (4), characterized by: the coupling module (2) comprises a first optical waveguide (2-1) and a second optical waveguide (2-2), the coupling module (2) is 3mm long, 3mm wide and 2mm high, the double-core optical fiber comprises a first fiber core (3-1), a second fiber core (3-2), a cladding (3-3), an etching groove (3-4) filled with magnetic fluid and a reflecting film (3-5), the laser light source (1) is coupled with the lower end of the first optical waveguide (2-1), the upper end of the first optical waveguide (2-1) is coupled with the first fiber core (3-1), the second fiber core (3-2) is coupled with the upper end of the second optical waveguide (2-2), the lower end of the second optical waveguide (2-2) is coupled with the detector (4), the etching groove (3-4) filled with magnetic fluid is obtained by etching the upper end face of the double-core optical fiber by using femtosecond laser, length 80um, wide 80um, dark 0.3um, reflectance coating (3-5) bond at the up end of two core fiber, thick 0.2 um.

2. The dual-core optical fiber magnetic field sensing probe of claim 1, wherein: the diameter of first optical waveguide (2-1) be 4um, the diameter of second optical waveguide (2-2) be 4um, 62.5um are apart from the upper end of first optical waveguide (2-1) and second optical waveguide (2-2), the lower extreme is apart from 1 mm.

3. The dual-core optical fiber magnetic field sensing probe of claim 1, wherein: the diameter of the double-core optical fiber cladding (3-3) is 125um, the diameter of the first fiber core (3-1) is 4um, the diameter of the second fiber core (3-2) is 4um, the interval between the two fiber cores is 62.5um, and the numerical aperture is 0.25.