CN106338702A - Temperature-insensitive magnetic field sensor based on magnetic fluid filling optical fiber microcavity - Google Patents
Temperature-insensitive magnetic field sensor based on magnetic fluid filling optical fiber microcavity Download PDFInfo
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/032—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
Abstract
The invention provides a temperature-insensitive magnetic field sensor based on a magnetic fluid filling optical fiber microcavity. The magnetic field sensor comprises a sensing head, an optical fiber coupler, a spectrograph and a wide-spectrum optical source. The sensing head is formed by an air chamber and a magnetic liquid cavity which are cascaded. An absolute value of a difference between free spectrum scopes of the air chamber and the magnetic liquid cavity is less than 1/10 of the magnetic liquid cavity. Wide spectrum light emitted by the wide-spectrum optical source enters into the sensing head via the optical fiber coupler. An optical signal reflected by the air chamber and the magnetic liquid cavity enters into the spectrograph via the optical fiber coupler. An optical signal reflected by the air chamber and the magnetic liquid cavity generates a vernier effect so that measured sensitivity of a magnetic field is greatly increased. An optical fiber support structure designed in the invention is fixed to a single-mode fiber and a panda fiber of two sides of the magnetic liquid cavity, and a thermal expansion effect of an optical fiber support is used to offset a thermo-optic effect of a magnetic fluid so that automatic compensation of a temperature is realized. The magnetic field sensor possesses advantages that the temperature can be automatically compensated; the structure is compact; sensitivity is high; and a measured range is large.
Description
Technical field
This patent is related to a kind of optical magnetic field sensors, and the temperature that a kind of magnetic fluid of specific design fills optical fiber microcavity is unwise
Sense magnetic field sensor.
Background technology
Fibre optic magnetic field sensor have have a safety feature, electromagnetism interference, non-cpntact measurement, can live real-time telemetry and dynamic
Many advantages, such as state measurement range is wide.In magnetic-field measurement and analysis field, fibre optic magnetic field sensor attracts numerous scholars to carry out
Research, and will be used widely in electric power detection industry.
Magnetic fluid is a kind of superparamagnetic characteristic liquid functional material answered Development of Modern Science and produce, almost solids-free magnetic
The hysteresis that property material has, its refractive index linearly changes within the specific limits with externally-applied magnetic field, and is easy to and optical fiber
Combine.The magnetic field sensing technology that magnetic fluid is combined with f-p chamber can make up based on Faraday effect magnetic field sensor Wal
Moral constant is relatively low and magnetic field sensor of based on giant magnetostrictive material is difficult to overcome the problem of hysteresis.But, due to
The thermo-optical coeffecient of magnetic fluid is very big, exceeds quartzy 2 orders of magnitude, and the therefore magnetic field sensor based on magnetic fluid must eliminate temperature
The interference of degree.At present, generally temperature is realized using the method for cascaded fiber grating and magnetic field measures, such as document 1(ri- simultaneously
qing lv, yong zhao, dan wang, and qi wang. magnetic fluid-filled optical
fiber fabry–pérot sensor for magnetic field measurement. ieee photonics
Technology letters, 26 (3): 217-219 (2014)).But, the method is unfavorable for sensor miniaturization and collection
Cheng Hua, sensitivity is limited by fbg measurement sensitivity, and can shorten the measurement range of interference-type magnetic field sensor.Additionally, sending out
Bright patent (application number cn 102221679 a) discloses the magnetic field sensor filling photonic crystal fiber based on magnetic fluid, although
Susceptibility using this sensor for temperature decreases, but does not enable temperature and be fully compensated, and this sensor is sensitive
Degree is low.
Content of the invention
Brief overview with regard to the present invention is given below, to provide basic with regard to certain aspects of the invention
Understand.It should be appreciated that this general introduction is not the exhaustive general introduction with regard to the present invention.It is not intended to determine the pass of the present invention
Key or pith, nor is it intended to limit the scope of the present invention.Its purpose only provides some concepts in simplified form,
In this, as the preamble in greater detail discussed after a while.
In consideration of it, the invention provides a kind of based on magnetic fluid fill optical fiber microcavity temperature-insensitive magnetic field sensor,
At least to solve the problems, such as that the existing magnetic field sensor based on magnetic fluid is sensitive to Temperature cross-over and sensitivity is low.
According to an aspect of the invention, it is provided a kind of temperature-insensitive magnetic field filling optical fiber microcavity based on magnetic fluid
Sensor, should include sensing head, fiber coupler, light based on the temperature-insensitive magnetic field sensor that magnetic fluid fills optical fiber microcavity
Spectrometer and wide spectrum light source；The wide spectrum optical that wide spectrum light source sends enters sensing head after fiber coupler, through sensing head reflection
Optical signal spectrometer is entered by fiber coupler.
Further, sensing head includes the first single-mode fiber part, the first hollow-core fiber part, the second single-mode fiber portion
Point, the second hollow-core fiber part, panda optic fibre part and structure of fiber_optic part；Wherein, one end of the first single-mode fiber part
With one end phase welding of the first hollow-core fiber part, the one of the other end of the first hollow-core fiber part and the second single-mode fiber part
End phase welding, the inside of the first hollow-core fiber part is air chamber；The other end of the second single-mode fiber part and the second hollow light
One end phase welding of fine part, the other end of the second hollow-core fiber part and panda optic fibre part phase welding, the second hollow-core fiber
Partial interior is magnetic current body cavity；One side opening is had on the side of panda optic fibre part, this side opening only with panda optic fibre part
One of two pores are connected；The pore being connected with side opening on the exposed ends end face of panda optic fibre part is closed.
Further, the length of the first hollow-core fiber part is 50 μm -200 μm, and the wall thickness of the first hollow-core fiber part is
20μm-50μm；The length of the second hollow-core fiber part is 50 μm -100 μm, and the wall thickness of the second hollow-core fiber part is 1 μm of -10 μ
m；First single-mode fiber segment outer radius, the first hollow-core fiber segment outer radius, the second single-mode fiber segment outer radius, the second hollow-core fiber
The external diameter of segment outer radius and panda optic fibre part is 125 μm；The inside of the first hollow-core fiber part is air chamber, and second is empty
The inside of core fibre part is magnetic current body cavity, and the absolute value of the difference of the Free Spectral Range of this air chamber and magnetic current body cavity is less than
The 1/10 of this magnetic current body cavity Free Spectral Range；In the covering of panda optic fibre part, two hole diameters are 10 μm -20 μm, two
Pore center distance is 25 μm -60 μm, and the length of panda optic fibre part is 10mm-20mm, the side opening diameter dimension of panda optic fibre
For 5 μm -20 μm, side opening is apart from the fusion point 2mm-5mm of panda optic fibre part and the second hollow-core fiber part.
Further, structure of fiber_optic one end is fixed on the second single-mode fiber, and the other end is fixed on panda optic fibre, and should
Two fixing ends are 1mm-10mm with the distance of the second hollow-core fiber part, and the sectional dimension of structure of fiber_optic is 10mm × 10mm.
Further, the spectral region of wide spectrum light source is 1300nm-1600nm.
The present invention employs air chamber and magnetic based on the temperature-insensitive magnetic field sensor that magnetic fluid fills optical fiber microcavity
The mode of fluid cavity cascade, makes this sensor with respect to single magnetic current body cavity magnetic field sensor (for example using cascade cursor effect
A) magnetic-field measurement sensitivity improves the 1-2 order of magnitude to patent of invention cn 102221679.Additionally, the present invention based on magnetic current
The magnetic field sensor that body fills optical fiber f-p chamber devises a structure of fiber_optic structure, and the thermal expansion effects using structure of fiber_optic can be complete
The full thermo-optic effect offsetting magnetic fluid, solves based on magnetic fluid filled-type magnetic field sensor to Temperature cross-over sensitive issue.
Method (such as document 1, ri-qing lv, yong zhao, dan wang, and qi wang. with respect to series connection fbg
magnetic fluid-filled optical fiber fabry–pérot sensor for magnetic field
Measurement. ieee photonics technology letters, 26 (3): 217-219 (2014)), this temperature
Compensation method compact conformation, sensitivity height, measurement range are big.
By the detailed description to highly preferred embodiment of the present invention below in conjunction with accompanying drawing, the these and other of the present invention is excellent
Point will be apparent from.
Brief description
The present invention can be by reference to being better understood below in association with the description given by accompanying drawing, wherein in institute
Have and employ same or analogous reference in accompanying drawing to represent same or like part.Described accompanying drawing is together with following
Describe the part comprising in this manual and being formed this specification together in detail, and be used for being further illustrated this
The preferred embodiment of invention and the principle and advantage explaining the present invention.In the accompanying drawings:
Fig. 1 is an example of the temperature-insensitive magnetic field sensor filling optical fiber microcavity based on magnetic fluid illustrating the present invention
Structural representation；
Fig. 2 is the schematic diagram of a kind of possible structure illustrating the sensing head shown in Fig. 1；
Fig. 3 is a kind of flow chart of exemplary process of the preparation method illustrating the sensing head for making the present invention；
Fig. 4 is to illustrate that air chamber cascades four beam interference models with magnetic current body cavity；
Fig. 5 is to illustrate that air chamber cascades interference spectrum envelope variation with magnetic current body cavity.
It will be appreciated by those skilled in the art that element in accompanying drawing be used for the purpose of simple and clear for the sake of and illustrate,
And be not necessarily drawn to scale.For example, in accompanying drawing, the size of some elements may be exaggerated with respect to other elements, with
Just it is favorably improved the understanding to the embodiment of the present invention.
Specific embodiment
Hereinafter in connection with accompanying drawing, the one exemplary embodiment of the present invention is described.For clarity and conciseness,
All features of actual embodiment are not described in the description.It should be understood, however, that developing any this actual enforcement
A lot of decisions specific to embodiment, to realize the objectives of developer, for example, symbol must be made during example
Close those restrictive conditions related to system and business, and these restrictive conditions may have with the difference of embodiment
Changed.Additionally, it also should be appreciated that although development is likely to be extremely complex and time-consuming, but to having benefited from the disclosure
For those skilled in the art of content, this development is only routine task.
Here is in addition it is also necessary to illustrate is a bit, in order to avoid having obscured the present invention because of unnecessary details, in the accompanying drawings
Illustrate only and the apparatus structure closely related according to the solution of the present invention and/or process step, and eliminate and the present invention
The little other details of relation.
The embodiment provides a kind of temperature-insensitive magnetic field sensor filling optical fiber microcavity based on magnetic fluid,
Should based on magnetic fluid fill optical fiber microcavity temperature-insensitive magnetic field sensor include sensing head, fiber coupler, spectrometer with
And wide spectrum light source；The wide spectrum optical that wide spectrum light source sends enters sensing head after fiber coupler, the light letter through sensing head reflection
Number spectrometer is entered by fiber coupler.
The temperature-insensitive magnetic field sensor being filled optical fiber microcavity based on magnetic fluid of the present invention to be described with reference to Fig. 1
100 example.As shown in figure 1, the temperature-insensitive magnetic field sensor filling optical fiber microcavity based on magnetic fluid of the present invention
Including wide spectrum light source 1-1, fiber coupler 1-2, sensing head 1-3 and spectrometer 1-4.Wide spectrum light source 1-1 is connected by optical fiber
Fiber coupler 1-2, fiber coupler 1-2 connect sensing head 1-3 by optical fiber, and spectrometer 1-4 connects light also by optical fiber
Fine coupler 1-2.So, the wide spectrum optical that wide spectrum light source 1-1 sends enters sensing head 1-3 after fiber coupler 1-2, through passing
The optical signal of sense head 1-3 reflection enters spectrometer 1-4 by fiber coupler 1-2.Wherein, the spectral region of wide spectrum light source 1-1
For example, 1300nm-1600nm.
According to a kind of implementation, as shown in Fig. 2 sensing head 1-3 can include the first single-mode fiber part 2-1, first
Hollow-core fiber part 2-2, the second single-mode fiber part 2-3, the second hollow-core fiber part 2-4, panda optic fibre part 2-5 and light
Fine holder part 2-6；Wherein, one end of the first single-mode fiber part 2-1 and one end phase of the first hollow-core fiber part 2-2 melt
Connect, one end phase welding of the other end of the first hollow-core fiber part 2-2 and the second single-mode fiber part 2-3；Second single-mode fiber
One end phase welding of the other end of part 2-3 and the second hollow-core fiber part 2-4, the other end of the second hollow-core fiber part 2-4
With panda optic fibre part 2-5 phase welding；One hole is had on the side of panda optic fibre part 2-5, as panda optic fibre part 2-5
Side opening, this side opening is only connected with one of two pores of panda optic fibre part 2-5；The exposed ends of panda optic fibre part 2-5
The pore being connected with side opening on (being its not that end with the second hollow-core fiber part 2-4 welding) end face is closed (for example
By resin glue, this pore is blocked)；The inside of the first hollow-core fiber part 2-2 is air chamber, the second hollow-core fiber part 2-4
Inside be magnetic current body cavity, and the absolute value of the difference of the Free Spectral Range of this air chamber and magnetic current body cavity be less than this magnetic current body cavity
The 1/10 of Free Spectral Range；One end of structure of fiber_optic part 2-6 is fixed in the second single-mode fiber part 2-3, and the other end is solid
It is scheduled in panda optic fibre part 2-5, and two fixing ends are 1mm-10mm with the distance of the second hollow-core fiber part 2-4.
Wherein, the length of the first hollow-core fiber part 2-2 is 50 μm -200 μm, and wall thickness is 20 μm -50 μm, the second hollow light
The length of fine part 2-4 is 50 μm -100 μm, and wall thickness is 1 μm -10 μm；First single-mode fiber part 2-1 external diameter, the first hollow light
Fine part 2-2 external diameter, the second single-mode fiber part 2-3 external diameter, the second hollow-core fiber part 2-4 external diameter and panda optic fibre part
The external diameter of 2-5 is identical, is 125 μm；In the covering of panda optic fibre part 2-5, two hole diameters are 10 μm -20 μm, two gas
For example, 25 μm -60 μm of Hole center distance, the length of panda optic fibre part 2-5 is, for example, 10mm-20mm；The side opening of panda optic fibre
A diameter of 5 μm -20 μm, panda optic fibre side opening is apart from the fusion point of panda optic fibre part 2-5 and the second hollow-core fiber part 2-4
2mm-5mm；The sectional dimension of structure of fiber_optic 2-6 is 10mm × 10mm.
The present invention adopts air chamber and magnetic current based on the temperature-insensitive magnetic field sensor that magnetic fluid fills optical fiber microcavity
The mode of body cavity cascade, makes this sensor (for example send out with respect to single magnetic current body cavity magnetic field sensor using cascade cursor effect
A) magnetic-field measurement sensitivity improves the 1-2 order of magnitude to bright patent cn 102221679.Additionally, the present invention based on magnetic fluid
The magnetic field sensor in filling optical fiber f-p chamber devises the miniature supporting structure of an optical fiber, and the thermal expansion effects using structure of fiber_optic support
The thermo-optic effect of demagnetization fluid, solves and fills the magnetic field sensor in f-p chamber to Temperature cross-over sensitive issue based on magnetic fluid.
The handling process of the example of the preparation method of sensing head for making the present invention is described with reference to Fig. 3
300.
As shown in figure 3, after handling process 300 starts, execution step s310.
In step s310, target first single-mode fiber and target the first hollow-core fiber welding adopt and welding two
Identical strength of discharge during single-mode fiber.Then execution step s320.
In step s320, with the fusion point of target first single-mode fiber and target first hollow-core fiber as starting point, in mesh
Mark one section of hollow-core fiber of intercepting on the first hollow-core fiber, the free end of this section of hollow-core fiber is melted with target second single-mode fiber
Connect, using 1/3 to 2/3 of strength of discharge during two single-mode fibers of welding, with target first single-mode fiber and mesh
Mark one air chamber of formation between the second single-mode fiber.Then execution step s330.
In step s330, target second single-mode fiber and target the second hollow-core fiber welding adopt and welding two
Identical strength of discharge during single-mode fiber.Then execution step s340.
In step s340, with the fusion point of target second single-mode fiber and target second hollow-core fiber as starting point, in mesh
Mark one section of hollow-core fiber of intercepting on the second hollow-core fiber, the free end of this section of hollow-core fiber and target panda optic fibre welding are adopted
Strength of discharge is 1/3 to 2/3 during two single-mode fibers of welding；Moving fiber makes electrode alignment second hollow of heat sealing machine
The center of fiber section, discharges 3-5 time, and the strength of discharge of employing is during two single-mode fibers of welding 1/3 to 2/3, so that the
The wall thickness of two hollow-core fibers is reduced to 1 μm -10 μm.Then execution step s350.
In step s350, with the fusion point of target second hollow-core fiber and target panda optic fibre as starting point, in target bear
One section of panda optic fibre is intercepted on cat optical fiber.Then execution step s360.
In step s360, a side opening is opened on the side of target panda optic fibre, make side opening only with target panda optic fibre
One of two pores are connected.Then execution step s370.
In step s370, under the microscope the free end end face of target panda optic fibre is amplified, will be connected with side opening
The pore of target panda optic fibre block.Then execution step s380.
In step s380, the free end of target panda optic fibre is inserted in magnetic fluid, and makes the side of target panda optic fibre
Hole expose in atmosphere, using capillarity by magnetic fluid be filled into the second hollow-core fiber partly interior so as to become magnetic current body cavity.
Then execution step s390.
In step s390, one end of structure of fiber_optic is fixed with the second single-mode fiber, and the other end is solid with panda optic fibre
Fixed.Handling process 300 terminates.
According to a kind of implementation, the length of the one section of hollow-core fiber intercepting on target first hollow-core fiber is 50 μm-
200 μm, wall thickness is 20 μm -50 μm, and the length of air chamber is 50 μm -200 μm；One section intercepting on target second hollow-core fiber
The length of hollow-core fiber is 50 μm -100 μm, and wall thickness is 1 μm -10 μm, and the length of magnetic current body cavity is 50 μm -100 μm；Air chamber and
The optical path difference of magnetic current body cavity is less than 10 wavelength；The external diameter of the external diameter of target panda optic fibre and target first single-mode fiber, the second list
The external diameter of the external diameter of mode fiber, the external diameter of the first hollow-core fiber and the second hollow-core fiber is 125 μm；Target panda optic fibre
Length is 10mm-20mm, and in the covering of target panda optic fibre, two hole diameters are 10 μm -20 μm, two pore center distance
For 25 μm -60 μm；A diameter of 5 μm -20 μm of panda optic fibre side opening, this side opening distance objective panda optic fibre and target second hollow
The fusion point 2mm-5mm of optical fiber.
Experimental data shows, not only can improve the measurement sensitivity in magnetic field using the sensing head that above method makes, and
And can be with compensation temperature to magnetic-field measurement impact.
Application example 1
One application of the temperature-insensitive magnetic field sensor 100 being filled optical fiber microcavity based on magnetic fluid of the present invention is described below
Example.
Under the influence of a magnetic field, magnetic fluid can produce mangneto and sells off effect, and its refractive index changes with the change in magnetic field, enters
And lead to the change of optical fiber microcavity light path, so that the interference spectrum translation of optical fiber microcavity, by detecting the big of interference spectrum translation
The little size that can obtain tested magnetic field.
Wide spectrum light source 1-1 adopts ase light source, and its spectral region is 1300nm-1600nm, and the wide spectrum optical sending is through 1 × 2 light
After fine coupler (as the example of fiber coupler 1-2), enter sensing head 1-3(air chamber and magnetic current body cavity), through sensing head
The optical signal of 1-3 reflection passes through above-mentioned 1 × 2 fiber coupler and enters spectrometer 1-4, is then realized to signal by computer again
Process.
The present invention based on the temperature-insensitive magnetic field sensor 100 that magnetic fluid fills optical fiber microcavity be based on air chamber and
Four beam interference principles of magnetic current body cavity cascade are realized, as shown in figure 4, therefore, it is dry that spectrometer 1-4 receives Interference Model
Relate to spectrum signal can be expressed as:
Formula one:
In formula one,e 1、e 2、e 3Withe 4It is respectively incident light in reflecting surfacee 1、e 2、e 3Withe 4On reflected light complex amplitude,iFor four
Beam interference composes light intensity.The Free Spectral Range δ of air chamberλ fsr1Free Spectral Range δ with magnetic current body cavityλ fsr2Meet δλ fsr1≈δλ fsr2When, four beam interference spectrum assume peak envelope phenomenon as shown in Figure 5, and peak envelope is rolled over magnetic fluid
Penetrate the change of rate and move.Peak envelope amount of movement δλ bl Variation relation with magnetic fluid refractive index is
Formula two:
In formula two,λ i For the oscillation wavelength of magnetic current body cavity, δn mf Variable quantity for magnetic fluid refractive index.With single magnetic current body cavity
Compare, the sensitivity after air chamber and the cascade of magnetic current body cavity increasesmTimes,mValue typically takes 10≤m≤40.
Magnetic fluid has mangneto and sells off characteristic, and magnetic field sensor 100 is exactly to realize magnetic field using this characteristic of magnetic fluid
Sensing.Under the influence of a magnetic field, magnetic fluid can produce mangneto and sells off effect, and its refractive index changes with the change in magnetic field, enters
And lead to the change of magnetic current body cavity light path, so that the interference spectrum translation of cascade air chamber and magnetic current body cavity, dry by detection
The size relating to spectrum translation can obtain the size in tested magnetic field.Substantially increased by the way of air chamber and the cascade of magnetic current body cavity
Magnetic-field measurement sensitivity, surveys with respect to single magnetic current body cavity magnetic field sensor (such as patent of invention cn 102221679 a) magnetic field
Amount sensitivity improves the 1-2 order of magnitude.
Application example 2
The sensing head temperature of the temperature-insensitive magnetic field sensor 100 being filled optical fiber microcavity based on magnetic fluid of the present invention is described below
Degree compensation principle.
Transducing head structure is as shown in Figure 2.Rectangle structure of fiber_optic two ends are separately fixed at the second single-mode fiber and panda optic fibre
On, and two fixing end distance the second hollow-core fibers have a certain distance.
The thermo-optical coeffecient of magnetic fluid high two orders of magnitude than quartz, therefore, the magnetic field sensor based on magnetic current body cavity is necessary
Consider the interference problem of temperature.This patent devises structure of fiber_optic structure, and the thermal expansion effects using structure of fiber_optic offset magnetic current
The thermo-optic effect of body.Analysis temperature compensation principle below:
The change of the magnetic current body cavity light path that magnetic fluid thermo-optic effect causes turns to
Formula three:
In formula three, δnThe change of the magnetic fluid refractive index causing for temperature,dFor the length of magnetic current body cavity,αFor magnetic fluid
Thermo-optical coeffecient, δtVariable quantity for temperature.
It is much larger than the metal of quartz from thermal expansion as structure of fiber_optic, structure of fiber_optic pulls on optical fiber when a temperature increases
So that it is extended.Due to the wall thickness of the second hollow-core fiber part very thin (between 1 m-10 m), therefore, its elastic modelling quantity is much smaller than
The elastic modelling quantity of panda optic fibre, therefore under structure of fiber_optic pulling force effect, the strain of the second hollow-core fiber part is much larger than second
Single-mode fiber part and panda optic fibre part, lead to the change of magnetic current body cavity light path to turn to
Formula four:
In formula four,nFor the refractive index of magnetic fluid, δdFor the elongation of magnetic current body cavity under pulling force effect,γFor structure of fiber_optic material
The thermal coefficient of expansion of material,a<1 is the ratio of single-mode fiber and the elastic modelling quantity of hollow-core fiber,b<1 is panda optic fibre and hollow-core fiber
Elastic modelling quantity ratio,dInterior length for structure of fiber_optic.
When the thermo-optic effect of thermal expansion effects and magnetic fluid is cancelled out each other, the variable quantity of magnetic current body cavity light path is zero, that is,
Formula five:
Formula three and formula four are substituted into formula five obtain:
Formula six:
As long as formula six is met, you can realize temperature self-compensation.By controlling wall thickness and the light of the second hollow-core fiber
The interior length of fine support can ensure that sensing head meets formula six.
The heat utilizing structure of fiber_optic based on the temperature-insensitive magnetic field sensor that magnetic fluid fills optical fiber microcavity of the present invention
Bulking effect completely cancels out the thermo-optic effect of magnetic fluid, solves based on magnetic fluid filled-type magnetic field sensor to Temperature cross-over
Sensitive issue.Method (such as document 1, ri-qing lv, yong zhao, dan wang, and with respect to series connection fbg
qi wang. magnetic fluid-filled optical fiber fabry–pérot sensor for magnetic
Field measurement. ieee photonics technology letters, 26 (3): 217-219 (2014)),
This temperature compensation compact conformation, sensitivity height, measurement range are big.
Application example 3
Described below for the temperature-insensitive magnetic field sensor 100 based on magnetic fluid filling optical fiber microcavity making the present invention
One application example of sensing head.
First, using general single mode fiber (as the example of target first single-mode fiber) and hollow-core fiber (as target the
The example of one hollow-core fiber) welding, strength of discharge and two general single mode fibers of welding under normal circumstances that welding adopts strong
Degree is identical.
Then, with the fusion point of general single mode fiber and hollow-core fiber as starting point, on hollow-core fiber, intercepted length is in 50 μ
One section of hollow-core fiber between m-200 μm, the free end of this section of hollow-core fiber is (single as target second with general single mode fiber
The example of mode fiber) welding.With the fusion point of hollow-core fiber and general single mode fiber as starting point, general single mode fiber intercepts
One section of general single mode fiber between 1mm-10mm for the length.
Then, using general single mode fiber and hollow-core fiber (as the example of target second hollow-core fiber) welding, welding is adopted
Strength of discharge is identical with the intensity of two general single mode fibers of welding under normal circumstances.
Then, moving fiber makes the center of electrode alignment the second hollow-core fiber part of heat sealing machine, discharges 3-5 time, adopts
Strength of discharge be two single-mode fibers of welding when 1/3 to 2/3 so that the wall thickness of the second hollow-core fiber is reduced to 1
μm-10μm.
Then, with the fusion point of general single mode fiber and the second hollow-core fiber as starting point, intercepted length on hollow-core fiber
One section of hollow-core fiber between 50 μm -100 μm, using the free end of this section of hollow-core fiber and panda optic fibre (as target panda
The example of optical fiber) welding.Wherein, the outside dimension of panda optic fibre, general single mode fiber and hollow-core fiber is identical, is 125 μ
M, a diameter of 10 μm -20 μm of diplopore in panda optic fibre covering, diplopore center distance is 25 μm -60 μm.Hollow-core fiber and panda light
The strength of discharge that fine welding adopts be the strength of discharge of two general single mode fibers of welding under normal circumstances 1/3 to 2/
3.So, the optical fiber microcavity that will form length between general single mode fiber and panda optic fibre at 50 μm -100 μm is (as mesh
The example of mark magnetic current body cavity).
Then, with the fusion point of general single mode fiber and panda optic fibre as starting point, a segment length is intercepted on panda optic fibre
Panda optic fibre between 10mm-20mm, then at the fusion point 2mm-5mm apart from general single mode fiber and panda optic fibre
One aperture (can femtosecond laser beat this hole) is opened on the side of panda optic fibre so as to only with one of two pores of panda optic fibre phase
Connection.
Then, under the microscope the end face of panda optic fibre is amplified, the panda optic fibre being connected with side opening with resin glue
Pore block.
Then, the free end of panda optic fibre is inserted it is ensured that the side opening of panda optic fibre exposes in atmosphere in magnetic fluid, profit
With capillarity, magnetic fluid is filled in optical fiber microcavity.
Finally, one end of structure of fiber_optic (as the example of target structure of fiber_optic) is fixed on the second single-mode fiber, separately
One end is fixed on panda optic fibre, and ensures that the distance between two fixing ends arelAnd two fixing point to the second hollow-core fiber portion
The distance divided is identical.
The sensing head being obtained therefrom has structure as shown in Figure 2, as shown in Fig. 2 in the sensing head made, target
The part of the first single-mode fiber correspond to Fig. 2 shown in the first single-mode fiber part 2-1, target first hollow-core fiber partly right
Should the first hollow-core fiber part 2-2 shown in Fig. 2, it is single that the part of target second single-mode fiber corresponds to second shown in Fig. 2
Mode fiber part 2-3, the part of target second hollow-core fiber corresponds to the second hollow-core fiber part 2-4 shown in Fig. 2, target bear
The part of cat optical fiber corresponds to panda optic fibre part 2-5 shown in Fig. 2, and the part of target structure of fiber_optic corresponds to shown in Fig. 2
Structure of fiber_optic part 2-6.
Although the present invention is described according to the embodiment of limited quantity, benefit from above description, the art
Interior it is clear for the skilled person that it can be envisaged that other embodiments in the scope of the present invention thus describing.Additionally, it should be noted that
Language used in this specification primarily to the purpose of readable and teaching and select, rather than in order to explain or limit
Determine subject of the present invention and select.Therefore, in the case of without departing from the scope of the appended claims and spirit, for this
For the those of ordinary skill of technical field, many modifications and changes will be apparent from.For the scope of the present invention, to this
It is illustrative and not restrictive for inventing done disclosure, and it is intended that the scope of the present invention be defined by the claims appended hereto.
Claims (5)
1. based on magnetic fluid fill optical fiber microcavity temperature-insensitive magnetic field sensor it is characterised in that described based on magnetic fluid
The temperature-insensitive magnetic field sensor of filling optical fiber microcavity includes sensing head, fiber coupler, spectrometer and wide spectrum light source；
Wherein, described sensing head include the first single-mode fiber part, the first hollow-core fiber part, the second single-mode fiber part,
Second hollow-core fiber part, panda optic fibre part and structure of fiber_optic part；Described structure of fiber_optic one end is fixed on described second
Single-mode fiber is partly gone up, and the described structure of fiber_optic other end is fixed on described panda optic fibre and partly goes up, and this two fixing end described with
The distance of described second hollow-core fiber part is 1mm-10mm；
Wherein, the inside of described first hollow-core fiber part is air chamber, and the inside of described second hollow-core fiber part is magnetic current
Body cavity, and the absolute value of the difference of the Free Spectral Range of this air chamber and magnetic current body cavity is less than this magnetic current body cavity Free Spectral Range
1/10；
Wherein, the wide spectrum optical that described wide spectrum light source sends enters described sensing head after described fiber coupler, through described biography
The optical signal of sense head reflection passes through described fiber coupler and enters described spectrometer.
2. the temperature-insensitive magnetic field sensor filling optical fiber microcavity based on magnetic fluid according to claim 1, its feature
It is, one end phase welding of one end of described first single-mode fiber part and described first hollow-core fiber part, described first is empty
One end phase welding of the other end of core fibre part and described second single-mode fiber part, described first hollow-core fiber partial interior
For air chamber；One end phase welding of the other end of described second single-mode fiber part and described second hollow-core fiber part, described
The other end of the second hollow-core fiber part and described panda optic fibre part phase welding, described second hollow-core fiber partial interior is magnetic
Fluid cavity；One side opening is had on the side of described panda optic fibre part, only with described panda optic fibre part two of this side opening
One of pore is connected；The pore being connected with described side opening in the exposed end face of described panda optic fibre part is closed.
3. the temperature-insensitive magnetic field sensing filling optical fiber microcavity based on magnetic fluid according to any one of claim 1-2
Device it is characterised in that described first hollow-core fiber part length be 50 μm -200 μm, the wall of described first hollow-core fiber part
Thickness is 20 μm -50 μm；The length of described second hollow-core fiber part be 50 μm -100 μm, described second hollow-core fiber part interior
Footpath is 1 μm -10 μm；The external diameter of described first hollow-core fiber part, the external diameter of described second hollow-core fiber part, described first list
The external diameter of the external diameter of mode fiber part, the external diameter of described second single-mode fiber part and described panda optic fibre part is 125 μ
m；The length of described panda optic fibre part is 10mm-20mm, and in the covering of described panda optic fibre part, two hole diameters are 10 μ
M-20 μm, described two pore center distance are 25 μm -60 μm；A diameter of 5 μm -20 μm of the side opening of described panda optic fibre, described
Side opening is apart from the fusion point 2mm-5mm of described panda optic fibre part and described hollow-core fiber part.
4. the temperature-insensitive magnetic field sensing filling optical fiber microcavity based on magnetic fluid according to any one of claim 1-3
Device is it is characterised in that the sectional dimension of described structure of fiber_optic is 10mm × 10mm.
5. the temperature-insensitive magnetic field sensing filling optical fiber microcavity based on magnetic fluid according to any one of claim 1-4
Device is it is characterised in that the spectral region of described wide spectrum light source is 1300nm-1600nm.
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