CN212483826U - Cladding carved rectangular groove filled liquid Bragg fiber grating magnetic field probe - Google Patents
Cladding carved rectangular groove filled liquid Bragg fiber grating magnetic field probe Download PDFInfo
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- CN212483826U CN212483826U CN202021098832.9U CN202021098832U CN212483826U CN 212483826 U CN212483826 U CN 212483826U CN 202021098832 U CN202021098832 U CN 202021098832U CN 212483826 U CN212483826 U CN 212483826U
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- 239000007788 liquid Substances 0.000 title claims abstract description 45
- 238000005253 cladding Methods 0.000 title claims abstract description 44
- 239000000523 sample Substances 0.000 title claims abstract description 38
- 239000013307 optical fiber Substances 0.000 claims abstract description 51
- 239000011553 magnetic fluid Substances 0.000 claims abstract description 16
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 11
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- 239000012530 fluid Substances 0.000 claims abstract description 5
- 238000004544 sputter deposition Methods 0.000 claims abstract description 5
- 238000005459 micromachining Methods 0.000 claims abstract description 4
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Abstract
The utility model belongs to the technical field of fiber grating sensing, in particular to a cladding is carved with rectangular channel and is filled liquid Bragg fiber grating magnetic field probe, it includes broadband light source, connecting optical fiber, optical fiber circulator, sensing probe, matching fluid, 1 x 2 fiber coupler 1, wave filter LPG1, wavelength division multiplexer, 1 x 2 fiber coupler 2, wave filter LPG2, photoelectric detector and signal processor; the left end optical fiber cladding of the sensing probe is formed by plating a silver metal film on the surface of the optical fiber cladding by using a vacuum sputtering coating technology to form a sensing FBG 1; the right end optical fiber cladding of the sensing probe is processed into a rectangular groove by using a femtosecond laser micromachining technology and is filled with magnetic fluid to form a sensing FBG 2. The utility model has the advantages that structure, preparation technology and theory of operation are simple, and the magnetic current body changes self refracting index along with the magnetic field intensity change, makes Bragg fiber grating resonance wavelength change, through the change condition of demodulation resonance wavelength, realizes the measurement to magnetic field intensity.
Description
Technical Field
The utility model belongs to the technical field of the fiber grating sensing, concretely relates to cladding is carved rectangular channel and is filled liquid Bragg fiber grating magnetic field probe.
Background
The fiber grating is a classical passive device of optical fiber, and the essence of the fiber grating is to periodically modulate the refractive index of the fiber core, so as to form a narrow-band filter which is transmissive or reflective. The fiber grating with the grating period less than 1 μm is called as short period fiber grating (FBG) according to the period size of the refractive index modulation; a fiber grating having a grating period of several tens or several hundreds of micrometers or more is called a Long Period Fiber Grating (LPFG). With the continuous improvement of the knowledge of the fiber bragg grating, the fiber bragg grating not only has the advantages of low manufacturing cost, strong anti-electromagnetic interference capability, good stability, small volume and the like, but also can be designed into sensors for measuring different physical quantities, such as magnetic fields, temperature, liquid level, strain and the like according to related physical bases.
Most of the traditional magnetic field sensors, such as hall sensors, fluxgate sensors, induction coil sensors, etc., have the disadvantages of large volume, complex structure, easy influence from complex environment, etc., and are difficult to apply in special fields. The fiber grating magnetic field sensor not only has the advantages of the fiber grating, can be applied to complex environments, but also can be designed to meet the requirements according to different sensing mechanisms. For example, the bragg fiber grating may be combined with a magnetic fluid, the optical fiber cladding may be grooved and filled with the magnetic fluid, the refractive index of the magnetic fluid is changed under an external magnetic field, and when the magnetic field direction is perpendicular to the direction of transmitting light, the refractive index decreases with the increase of the external magnetic field, thereby causing the wavelength change of the output light, and the signal may be demodulated by the edge filtering demodulation technique to realize the measurement of the magnetic field strength.
The utility model discloses utilize short period Bragg fiber grating, recycle femto second laser micro-processing technique and get rid of partial fiber cladding, at the surperficial silvering metal film that does not get rid of the fiber cladding region, reuse quartz glass capillary encapsulates, uses the syringe to pack the magnetic fluid in to the cladding, makes sensing probe, and through border filtering demodulation technique, the demodulation output light wave intensity and the big or small situation of change of wavelength realize the measurement to magnetic field intensity at last.
SUMMERY OF THE UTILITY MODEL
The utility model discloses aim at realizing the measurement to magnetic field intensity, designed the covering and carved the rectangular channel and fill liquid Bragg fiber grating magnetic field probe.
Cladding is carved rectangular channel and is filled liquid Bragg fiber grating magnetic field probe, its structure includes broadband light source (1), connecting fiber (2), optic fibre circulator (3), sensing probe (4), matching fluid (5), 1 x 2 fiber coupler 1(6), wave filter LPG1(7), wavelength division multiplexer (8), 1 x 2 fiber coupler 2(9), wave filter LPG2(10), photoelectric detector (11) and signal processor (12), its characterized in that: light emitted by a broadband light source (1) enters an optical fiber circulator (3) from a port 1 through a connecting optical fiber (2), then enters a sensing probe (4) from a port 2 of the optical fiber circulator, one part of light waves are reflected back to the optical fiber circulator (3) from the port 2, the other part of light waves enter matching liquid (5) to be absorbed, the reflected light waves enter a wavelength division multiplexer (8) from the port 3, then are divided into two beams of light which respectively pass through a 1 x 2 optical fiber coupler 1(6) and a 1 x 2 optical fiber coupler 2(9), then respectively pass through a filter LPG1(7) and a filter LPG2(10), optical signals are detected by a photoelectric detector (11), and finally, a signal processor (12) is used for signal analysis; the sensing probe (4) structure comprises an optical fiber core (4-1), an optical fiber cladding (4-2), a liquid-filled cladding region (4-3), a quartz glass capillary tube (4-4), a liquid-filled channel (4-5), a sensing FBG1(4-6), a silver metal film (4-7) and a sensing FBG2 (4-8). The diameter of the optical fiber core (4-1) is 8 μm, Bragg gratings are engraved on the core, the diameter of the optical fiber cladding (4-2) is 125 μm, the depth of the liquid-filled cladding region (4-3) is 40 μm, the length is 5mm, the width is 60 μm, the quartz glass capillary tube (4-4) is used for packaging the sensing probe (4), the inner diameter is 135 μm, the outer diameter is 1000 μm, the liquid-filled channel (4-5) is formed by processing through a femtosecond laser processing technology, and the silver metal film (4-7) is plated through a vacuum sputtering method, and the thickness is 200 nm.
The total length of the sensing probe (4) is 1cm, the structure of the sensing probe comprises a sensing FBG1(4-6) with an optical fiber cladding plated with a silver metal film (4-7) and a sensing FBG2(4-8) with the optical fiber cladding removed and filled with a magnetic sensitive liquid, the lengths of the sensing FBG1(4-6) and the sensing FBG2(4-8) are respectively 5mm, the Bragg grating period of an optical fiber core is 520nm, the refractive index of the fiber core is 1.465, and the central wavelength is 1523 nm.
The liquid in the cladding region (4-3) filled with the liquid is magnetic fluid, two filling liquid channels (4-5) processed by a femtosecond laser micromachining technology are arranged on the surface of the cladding region, the magnetic fluid is filled into the cladding region through one filling liquid channel (4-5) by using an injector, the magnetic fluid is filled when the liquid overflows from the other filling liquid channel (4-5), finally, UV glue is coated at the port of the filling liquid channel (4-5), and then ultraviolet light is used for irradiation and encapsulation.
Drawings
Fig. 1 is a schematic view of the working structure of the cladding-engraved rectangular groove-filled liquid bragg fiber grating magnetic field probe of the present invention;
fig. 2 is a schematic structural diagram of the sensing probe of the present invention.
Detailed Description
The following is a more detailed description of the present invention, taken in conjunction with the accompanying drawings and detailed description of the preferred embodiments.
As shown in fig. 1, a broadband light source (1), a connecting optical fiber (2), an optical fiber circulator (3), a sensing probe (4), matching fluid (5), a 1 × 2 optical fiber coupler 1(6), a filter LPG1(7), a wavelength division multiplexer (8), a 1 × 2 optical fiber coupler 2(9), a filter LPG2(10), a photodetector (11), and a signal processor (12) are connected in the manner shown in fig. 1.
As shown in fig. 2, an optical fiber core (4-1), an optical fiber cladding (4-2), a liquid-filled cladding region (4-3), a silica glass capillary tube (4-4), a liquid-filled channel (4-5), a sensing FBG1(4-6), a silver metal film (4-7), and a sensing FBG2 (4-8).
The sensing probe (4) of the utility model combines the structure shown in figure 2, the specific manufacturing process is as follows,
the method comprises the following steps: optical fiber end face pretreatment
The utility model selects the common Bragg fiber grating, the fiber core diameter is 8 μm, the cladding diameter is 125 μm, the Bragg grating period is 520nm, the central wavelength is 1523nm and the total length is 1 cm. And removing the coating layer on the surface of the Bragg fiber grating, and cleaning the single-mode fiber by using an ultrasonic cleaner.
Step two: femtosecond laser removing part of optical fiber cladding
Fixing the Bragg fiber grating of the first step on a four-dimensional precision moving platform to ensure that the Bragg fiber grating is placed in parallel relative to the platform; setting relevant parameters of the femtosecond laser; then, the computer is used for controlling the moving platform to move, so that the surface of the sensing probe fiber cladding moves parallel to the platform, the purpose of removing the fiber cladding with the length of 5mm at the right end of the fiber is achieved, and a rectangular groove with the depth of 40 microns, the length of 5mm and the width of 60 microns is formed in the fiber cladding, as shown in the structure of fig. 2.
Step three: optical fiber cladding surface metal coating film
And D, plating a metal film on the surface of the left end of the optical fiber of the sensing probe by the Bragg fiber grating in the step two through a vacuum sputtering coating technology, covering the right end part of the optical fiber cladding of the sensing probe by a high-temperature-resistant adhesive tape, performing vacuum sputtering coating for four times, rotating the sensing probe by 90 degrees after each coating is finished, and then re-coating the film to finally achieve the purpose of uniform coating. The silver metal film had a thickness of 200nm and a length of 5 mm.
Step four: encapsulating optical fibers and cladding fill fluids
Firstly, a quartz glass capillary tube and a sensing probe are fixed on a four-dimensional precision moving platform in parallel with the surface of the platform, and the Bragg fiber grating processed in the step three is slowly inserted into the quartz glass capillary tube by utilizing a computer control platform. After the insertion, the left and right ends are coated with UV glue and then encapsulated by irradiation with ultraviolet light. And processing a liquid filling channel on the surface of the quartz glass capillary tube right above the rectangular groove area, which is close to the edge of the right end by 1mm by using a femtosecond laser micromachining technology, moving the liquid filling channel to the left by 3mm in parallel relative to the liquid filling channel, and then processing a second liquid filling channel, wherein the two processed liquid filling channels are used as channels for filling the magnetic fluid. And finally, injecting the magnetic fluid into the rectangular groove from any one of the liquid filling channels by using an injector, and indicating that the filling is finished when the magnetic fluid overflows from the other liquid filling channel. And finally, smearing the two gaps with UV glue, irradiating with ultraviolet light, and packaging. The quartz glass capillary had an inner diameter of 135 μm and an outer diameter of 1000. mu.m. After the above steps of the manufacturing process are successfully completed, the sensor probe is completely manufactured, and device connection is performed according to the structure shown in fig. 1.
The formula of the resonant wavelength of the bragg fiber grating:
λ0＝2neffΛ
wherein n iseffIs the effective refractive index of the Bragg fiber grating, and Λ is the period of the Bragg fiber grating0The center resonant wavelength. The surface of the optical fiber cladding layer of the sensing FBG1 is plated with a silver metal film, when the external temperature changes, the silver metal film expands with heat and contracts with cold, so that the period of the Bragg optical fiber grating of the sensing FBG1 changes, the resonance wavelength changes accordingly, and the change condition of the resonance wavelength is analyzed to reflect the external temperature.
The filling liquid is magnetic fluid which is sensitive to the change of an applied magnetic field, the refractive index of the magnetic fluid can change along with the change of the magnetic field intensity, and the fiber cladding is filled with the sensing FBG2 of the magnetic fluid, and the resonant wavelength of the fiber cladding can change according to the change of the magnetic field intensity.
The wavelength division multiplexer is specially designed, and two different transmission windows are designed according to the resonant wavelengths of the sensing FBG1 and the sensing FBG2, so that the resonant wavelength lambda is enabled1And resonance wavelength lambda2Respectively entering different demodulation systems.
Resonant wavelength λ1The light is divided into two beams through a 1 multiplied by 2 optical fiber coupler 1, and one beam directly enters a photoelectric detector to be used as a reference light path; the other beam of light passes through a filter LPG1 such that the resonant wavelength λ is1Falls on the linear part at the right side of the transmission spectrum of the filter LPG1 and is subjected to linear filtering processing. Resonant wavelength λ2Process and resonance wavelength lambda of1Similarly.
The utility model discloses the basic operating principle that rectangular channel was carved to the covering was filled liquid Bragg fiber grating magnetic field probe does: light emitted by a broadband light source enters the optical fiber circulator from the port 1 and then enters the sensing probe from the port 2 of the optical fiber circulator, the sensing FBG1 is sensitive to outside temperature and the sensing FBG2 is sensitive to an external magnetic field and respectively reflects specific wavelengths, the reflected light returns to the optical fiber circulator from the port 2 and then enters the wavelength division multiplexer from the port 3 of the optical fiber circulator, the reflected light is divided into two beams of light which enter different demodulation systems and respectively enter the different demodulation systemsFor resonant wavelength lambda1And resonance wavelength lambda2Linear filtering is carried out, and finally, signal processing and analysis are carried out by a photoelectric detector and a signal processor to achieve the aim of measuring the magnetic field intensity.
Claims (3)
1. Cladding is carved rectangular channel and is filled liquid Bragg fiber grating magnetic field probe, its structure includes broadband light source (1), connecting fiber (2), optic fibre circulator (3), sensing probe (4), matching fluid (5), 1 x 2 fiber coupler 1(6), wave filter LPG1(7), wavelength division multiplexer (8), 1 x 2 fiber coupler 2(9), wave filter LPG2(10), photoelectric detector (11) and signal processor (12), its characterized in that: light emitted by a broadband light source (1) enters an optical fiber circulator (3) from a port 1 through a connecting optical fiber (2), then enters a sensing probe (4) from a port 2 of the optical fiber circulator, one part of the light is reflected back to the optical fiber circulator (3) from the port 2, the other part of the light enters matching liquid (5) to be absorbed, the reflected light enters a wavelength division multiplexer (8) from the port 3, then is divided into two beams of light which respectively pass through a 1 x 2 optical fiber coupler 1(6) and a 1 x 2 optical fiber coupler 2(9), then respectively passes through a filter LPG1(7) and a filter LPG2(10), an optical signal is detected by a photoelectric detector (11), and finally is analyzed by a signal processor (12), wherein the sensing probe (4) structurally comprises an optical fiber core (4-1), an optical fiber cladding (4-2), and a cladding area (4-3) filled with liquid, Quartz glass capillary tube (4-4), liquid filling channel (4-5), sensing FBG1(4-6), silver metal film (4-7) and sensing FBG2(4-8), the diameter of the optical fiber core (4-1) is 8 μm, Bragg grating is engraved on the core, the diameter of the optical fiber cladding (4-2) is 125 μm, the depth of the liquid filling cladding region (4-3) is 40 μm, the length is 5mm, the width is 60 μm, the quartz glass capillary tube (4-4) is used for packaging the sensing probe (4), the inner diameter is 135 μm, the outer diameter is 1000 μm, the liquid filling channel (4-5) is processed by femtosecond laser processing technology, the silver metal film (4-7) is plated by vacuum sputtering and has a thickness of 200nm, the sensing FBG1(4-6) can measure the external temperature, and the parameters of the magnetic field intensity measured by the sensing FBG2(4-8) can be subjected to temperature compensation.
2. The cladding-engraved rectangular slot liquid-filled bragg fiber grating magnetic field probe as claimed in claim 1, wherein: the total length of a sensing probe (4) is 1cm, the structure of the sensing probe comprises a 5mm sensing FBG1(4-6) and a 5mm sensing FBG2(4-8), the sensing FBG1(4-6) is plated with a silver metal film (4-7) in an optical fiber cladding, the sensing FBG2(4-8) is removed from the optical fiber cladding and is filled with a magnetic sensitive liquid, the Bragg grating period is 520nm, the refractive index of a fiber core is 1.465, and the central wavelength is 1523 nm.
3. The cladding-engraved rectangular slot liquid-filled bragg fiber grating magnetic field probe as claimed in claim 1, wherein: the liquid in a cladding region (4-3) filled with liquid in a sensing probe (4) is magnetic fluid, the surface of the cladding region is provided with two liquid filling channels (4-5) processed by a femtosecond laser micromachining technology, and the magnetic fluid is filled into the cladding region through the liquid filling channels (4-5) by using a syringe.
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| CN202021098832.9U CN212483826U (en) | 2020-06-15 | 2020-06-15 | Cladding carved rectangular groove filled liquid Bragg fiber grating magnetic field probe |
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| CN202021098832.9U CN212483826U (en) | 2020-06-15 | 2020-06-15 | Cladding carved rectangular groove filled liquid Bragg fiber grating magnetic field probe |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111537923A (en) * | 2020-06-15 | 2020-08-14 | 中国计量大学 | Cladding carved rectangular groove filled liquid Bragg fiber grating magnetic field probe |
| CN114552342A (en) * | 2022-01-13 | 2022-05-27 | 北京交通大学 | Photoelectric oscillator magnetic field sensing device based on corrosion type polarization maintaining fiber bragg grating |
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2020
- 2020-06-15 CN CN202021098832.9U patent/CN212483826U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111537923A (en) * | 2020-06-15 | 2020-08-14 | 中国计量大学 | Cladding carved rectangular groove filled liquid Bragg fiber grating magnetic field probe |
| CN114552342A (en) * | 2022-01-13 | 2022-05-27 | 北京交通大学 | Photoelectric oscillator magnetic field sensing device based on corrosion type polarization maintaining fiber bragg grating |
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