A temperature-compensated optical fiber magnetic field sensor based on self-referenced resonant reflection optical waveguide and a preparation method thereof

Abstract

The application discloses a temperature compensation optical fiber magnetic field sensor based on a self-reference resonant reflection optical waveguide and a preparation method thereof, wherein the preparation method comprises the following steps: fusing the two ends of two hollow core silica tubes I with standard single-mode optical fibers one by one; coaxially inserting one of the hollow core silica tubes I into a first hollow core silica tube II, and then packaging one end of the coaxial hollow core silica tube I and the first hollow core silica tube II and placing the same into alcohol; when the alcohol enters the first hollow core silica tube II and wraps the corresponding hollow core silica tube I, the other end of the coaxial hollow core silica tube I and the first hollow core silica tube II is packaged; coaxially inserting the other hollow core silica tube I into a second hollow core silica tube II, and then packaging one end of the coaxial hollow core silica tube I and the second hollow core silica tube II and placing the same into magnetic fluid; when the magnetic fluid enters the second hollow core silica tube II and wraps the hollow core silica tube I, the other end of the coaxial hollow core silica tube I and the second hollow core silica tube II is packaged. The application can eliminate temperature crosstalk in magnetic field measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to a temperature-compensated optical fiber magnetic field sensor based on a self-referenced resonant reflection optical waveguide and a preparation method thereof, and belongs to the technical field of optical fiber sensing. BACKGROUND

[0002] Magnetic field measurement has important significance in many scientific research and engineering technical fields, especially in the fields of power systems, electromagnetic compatibility and microwave technology. For example, in electromagnetic scientific research, magnetic field measurement can be used as an effective means to verify the accuracy of electromagnetic theory calculation and provide measurement values for many difficult-to-calculate magnetic field environments; in the power industry, magnetic field measurement can be used for power system state detection, magnetic field distribution measurement inside and outside electrical equipment, etc.; in the field of electromagnetic compatibility research, magnetic field measurement can be used to detect the external electromagnetic radiation and interference of electrical and electronic equipment, and to study the influence of environmental magnetic field on the operation of electronic instruments; in microwave technology, the magnetic field around microwave transmitting and receiving equipment needs to be measured.

[0003] Traditional magnetic field sensors generally measure and calculate magnetic fields through Hall effect, Faraday magneto-optic effect, giant magneto-inductive effect, magnetic saturation effect, etc. However, active metal probes can disturb the distribution of the measured magnetic field, making the measurement inaccurate, and the cable for transmitting signals can generate noise, which brings inconvenience to the processing and analysis of the detection signal. Therefore, traditional magnetic field sensors have the disadvantages of low electromagnetic interference resistance, low sensitivity, and large loss.

[0004] Micro-nano optical fiber magnetic field sensors are very sensitive to the refractive index changes of the surrounding evanescent field, so they can improve the sensitivity of magnetic field measurement. Such micro-nano optical fiber magnetic field sensors use a method of wrapping micro-nano optical fibers with magnetic fluid to prepare a magnetic field sensing head. However, micro-nano optical fibers are expensive to prepare, and their mechanical strength is low and they are prone to breakage.

[0005] In recent years, all-optical fiber magnetic field sensors with magnetic fluid filled tapered microstructure and transverse offset structure optical fiber interferometers have also been reported. All-optical fiber magnetic field sensors based on the tunable refractive index characteristics of magnetic fluid have the advantages of high sensitivity, linear response, and small volume. However, due to the Poisson effect of optical fibers, optical fiber sensors often have serious temperature cross-sensitivity problems. In addition, temperature can also change the refractive index value of magnetic fluid, affecting the measurement accuracy of the magnetic field.

[0006] In view of the deficiencies of the prior art, the present application designs a temperature-compensated optical fiber magnetic field sensor based on a self-referenced resonant reflection optical waveguide to solve the above problems. SUMMARY

[0007] The present application aims at overcoming the deficiencies in the prior art, and provides a temperature-compensated optical fiber magnetic field sensor based on a self-referenced resonant reflection optical waveguide and a preparation method thereof, which can eliminate temperature crosstalk during magnetic field measurement.

[0008] To achieve the above-mentioned purpose, the present application is implemented by using the following technical scheme:

[0009] In one aspect, the present application provides a preparation method of a temperature-compensated optical fiber magnetic field sensor based on a self-referenced resonant reflection optical waveguide, comprising the following steps:

[0010] The standard single-mode optical fiber, the first hollow silicon tube I and the second hollow silicon tube I are obtained, and the coating layers of the obtained standard single-mode optical fiber, the first hollow silicon tube I and the second hollow silicon tube I are stripped and then wiped with alcohol for standby use;

[0011] The two ends of the standby first hollow silicon tube I and the two ends of the second hollow silicon tube I are respectively fused with the standard single-mode optical fiber one by one, and the first hollow silicon tube I is arranged opposite to the second hollow silicon tube I;

[0012] The first hollow silicon tube I fused with the standard single-mode optical fiber is coaxially inserted into the first hollow silicon tube II, and one end of the coaxial first hollow silicon tube I and the first hollow silicon tube II is packaged and then placed in alcohol, and when the alcohol enters the first hollow silicon tube II and wraps the first hollow silicon tube I, the other end of the coaxial first hollow silicon tube I and the first hollow silicon tube II is packaged.

[0013] The second hollow silicon tube I fused with the standard single-mode optical fiber is coaxially inserted into the second hollow silicon tube II, and one end of the coaxial second hollow silicon tube I and the second hollow silicon tube II is packaged and then placed in magnetic fluid, and when the magnetic fluid enters the second hollow silicon tube II and wraps the second hollow silicon tube I, the other end of the coaxial second hollow silicon tube I and the second hollow silicon tube II is packaged.

[0014] Further, the length of the standard single-mode optical fiber is 1.5 cm.

[0015] Further, the length of the first hollow silicon tube I and the second hollow silicon tube I is 5 mm.

[0016] Further, the distance between the first hollow silicon tube I and the second hollow silicon tube I is 1 cm.

[0017] Further, the inner diameter of each hollow silicon tube I is 75 μm, and the outer diameter is 150 μm; the inner diameter of each hollow silicon tube II is 240 μm, and the outer diameter is 300 μm.

[0018] In another aspect, the present application provides a temperature-compensated optical fiber magnetic field sensor based on a self-referenced resonant reflection optical waveguide, which is prepared by using the above-mentioned preparation method of a temperature-compensated optical fiber magnetic field sensor based on a self-referenced resonant reflection optical waveguide.

[0019] Further, the temperature-compensated optical fiber magnetic field sensor based on the self-referenced resonant reflection optical waveguide comprises a single-mode optical fiber and two resonant cavities.

[0020] The two resonant cavities are oppositely arranged on the single-mode optical fiber, wherein one resonant cavity is only sensitive to temperature, and the other resonant cavity is sensitive to both temperature and magnetic field.

[0021] Further, one resonant cavity comprises coaxially arranged first hollow silicon tube I and first hollow silicon tube II, and the first hollow silicon tube I and the first hollow silicon tube II are filled with alcohol; the other resonant cavity comprises coaxially arranged second hollow silicon tube I and second hollow silicon tube II, and the second hollow silicon tube I and the second hollow silicon tube II are filled with magnetic fluid.

[0022] Further, the distance between the oppositely arranged two resonant cavities is 1 cm.

[0023] Further, the length of the two resonant cavities is 5 mm.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The present application can eliminate the temperature crosstalk in magnetic field measurement by fusing and packaging the standard single-mode optical fiber and the hollow silicon tube I and the hollow silicon tube II, and by filling different liquids between the hollow silicon tube I and the hollow silicon tube II, so as to obtain the temperature-compensated optical fiber magnetic field sensor with the self-referenced resonant reflection optical waveguide, and the preparation process is simple, the preparation cost is low, and the performance of the finished product is stable.

[0026] The present application can eliminate the temperature crosstalk in magnetic field measurement by fusing and packaging the standard single-mode optical fiber and the hollow silicon tube I and the hollow silicon tube II, and by filling different liquids between the hollow silicon tube I and the hollow silicon tube II, so as to obtain the temperature-compensated optical fiber magnetic field sensor with the self-referenced resonant reflection optical waveguide, and the preparation process is simple, the preparation cost is low, and the performance of the finished product is stable. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The figure shows a flow chart of one embodiment of the preparation method of the temperature-compensated optical fiber magnetic field sensor of the present application.

[0028] Figure 2 The figure shows a structural schematic diagram of one embodiment of the temperature-compensated optical fiber magnetic field sensor of the present application.

[0029] In the figure: 1, single-mode optical fiber; 2, resonant cavity; 21, second hollow silicon tube I; 22, second hollow silicon tube II; 31, inner wall; 32, outer wall I; 33, outer wall II. DETAILED DESCRIPTION

[0030] The application will be further described below with reference to the drawings. The following examples are only used to more clearly illustrate the technical solutions of the application, and cannot be used to limit the protection scope of the application.

[0031] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used for description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0032] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] Example 1

[0034] The embodiment provides a preparation method of a temperature compensation optical fiber magnetic field sensor based on a self-reference resonant reflection optical waveguide, and the preparation method comprises the following steps: Figure 1 , comprising the following steps:

[0035] S1 obtains a standard single-mode optical fiber, a first hollow silicon tube I and a second hollow silicon tube I, peels off the coating layers of the obtained standard single-mode optical fiber, the first hollow silicon tube I and the second hollow silicon tube I, and then wipes them clean with cotton dipped in alcohol for standby.

[0036] In application, the initial lengths of the standard single-mode optical fiber, the first hollow silicon tube I and the second hollow silicon tube I are all the same, and all parameters of the first hollow silicon tube I and the second hollow silicon tube I are consistent.

[0037] In application, the initial lengths of the standard single-mode optical fiber, the first hollow silicon tube I and the second hollow silicon tube I are all 1.5 cm.

[0038] S2 uses the optical fiber fusion splicer to fuse the two ends of the standby first hollow core silica tube I and the two ends of the second hollow core silica tube I with the standard single-mode optical fiber respectively, and the first hollow core silica tube I is arranged opposite to the second hollow core silica tube I.

[0039] In application, first, the standby standard single-mode optical fiber and the first hollow core silica tube I are respectively placed in the clamp of the optical fiber fusion splicer, the clamp is closed, the standard single-mode optical fiber and the first hollow core silica tube I cannot be loosened, then the discharge parameters of the optical fiber fusion splicer are set, the power supply is connected for discharge, the one end of the standard single-mode optical fiber and the first hollow core silica tube I is fused, then the clamp is opened, the first hollow core silica tube I is moved with the help of the optical moving platform, the first hollow core silica tube I is cut, the reserved length of the first hollow core silica tube I is 5mm, the reserved cross section of the first hollow core silica tube I is fused with the standard single-mode optical fiber by using the optical fiber fusion splicer. Finally, the above steps are repeated to fuse the two ends of the second hollow core silica tube I with the standard single-mode optical fiber respectively, and the distance between the first hollow core silica tube I and the second hollow core silica tube I after fusion is 1cm, and the length of the first hollow core silica tube I and the second hollow core silica tube I is 5mm.

[0040] S3 uses the three-dimensional adjusting device to coaxially insert the first hollow core silica tube I fused with the standard single-mode optical fiber into the first hollow core silica tube II, and the one end of the coaxial first hollow core silica tube I and the first hollow core silica tube II is packaged and placed in alcohol, due to the capillary tension, alcohol enters the first hollow core silica tube II, when alcohol wraps the first hollow core silica tube I, the other end of the coaxial first hollow core silica tube I and the first hollow core silica tube II is packaged.

[0041] In application, the inner diameter of the first hollow core silica tube II is much larger than the outer diameter of the first hollow core silica tube I.

[0042] In application of the embodiment, the inner diameter of each hollow core silica tube I is 75μm, and the outer diameter is 150μm; the inner diameter of each hollow core silica tube II is 240μm, and the outer diameter is 300μm.

[0043] S4 coaxially inserts the second hollow core silica tube I fused with the standard single-mode optical fiber into the second hollow core silica tube II, and the one end of the coaxial second hollow core silica tube I and the second hollow core silica tube II is packaged and placed in magnetic fluid, due to the capillary tension, magnetic fluid enters the second hollow core silica tube II, when magnetic fluid wraps the second hollow core silica tube I, the other end of the coaxial second hollow core silica tube I and the second hollow core silica tube II is packaged.

[0044] In application, all parameters of the second hollow core silica tube II are consistent with those of the first hollow core silica tube II.

[0045] The application obtains the temperature-compensated optical fiber magnetic field sensor with the self-referenced resonant reflective optical waveguide by fusing and packaging the standard single-mode optical fiber and the hollow core silicon tube I and the hollow core silicon tube II, and by filling different liquids between the hollow core silicon tube I and the hollow core silicon tube II, so that the preparation process is simple, the preparation cost is low, and the performance of the finished product is stable.

[0046] Embodiment 2

[0047] This embodiment introduces in detail a kind of temperature-compensated optical fiber magnetic field sensor based on self-referenced resonant reflective optical waveguide, which is prepared by the preparation method of the temperature-compensated optical fiber magnetic field sensor based on self-referenced resonant reflective optical waveguide recorded in embodiment 1.

[0048] Reference Figure 2 The temperature-compensated optical fiber magnetic field sensor based on self-referenced resonant reflective optical waveguide of this embodiment includes a single-mode optical fiber 1 and two resonant cavities 2, which are oppositely arranged on the single-mode optical fiber 1, and the distance between the two resonant cavities 2 is 1 cm. The length of the two resonant cavities 2 is 5 mm.

[0049] One resonant cavity includes coaxially arranged first hollow core silicon tube I and first hollow core silicon tube II, and the first hollow core silicon tube I and the first hollow core silicon tube II are filled with alcohol, so that the resonant cavity is only sensitive to temperature; the other resonant cavity includes coaxially arranged second hollow core silicon tube I 21 and second hollow core silicon tube II 22, and the second hollow core silicon tube I 21 and the second hollow core silicon tube II 22 are filled with magnetic fluid, so that the resonant cavity is sensitive to both temperature and magnetic field.

[0050] When the temperature-compensated optical fiber magnetic field sensor based on self-referenced resonant reflective optical waveguide of this embodiment is applied, Figure 2 the light beam is transmitted along the single-mode optical fiber 1, and when the light beam reaches the first resonant cavity, the light beam can be reflected by the outer wall I 32, the outer wall II 33 and the inner wall 31. At this time, the resonant cavity can be regarded as a double-layered Fabry-Perot standard.

[0051] When the optical wavelength of the resonant cavity is at the resonant wavelength, i.e. at the optical wavelength of an integer multiple of light, most of the light passes through the sidewall of the first hollow core silicon tube I, resulting in a sharp periodic drop in the resonant wavelength in the transmission spectrum of the resonant cavity.

[0052] When the optical wavelength of the resonant cavity gradually deviates from the resonant wavelength, more light is confined in the first hollow core silicon tube I, and the light loss gradually decreases.

[0053] When the optical wavelength of the resonant cavity deviates from the resonant wavelength, the light is reflected by the inner wall 31 and confined in the first hollow core silicon tube I as a guided core mode. At this time, the first hollow core silicon tube I plays the role of resonant reflective optical waveguide, i.e. constrains the transmission of light wave. A periodic and narrow lossy recess corresponding to the resonance condition of the resonant cavity appears in the transmission spectrum of the resonant cavity, which can be seen from formulas (1) and (2).

[0054]

[0055]

[0056] In the formula, λ ER is the resonant wavelength of the alcohol- wrapped resonant cavity, λ MR is the resonant wavelength of the magnetic fluid- wrapped resonant cavity, d1 is the cladding thickness of the hollow silicon tube I, d2 is the thickness of the liquid filled between the hollow silicon tube I and the hollow silicon tube II, n1 is the cladding refractive index of the hollow silicon tube I, n air is the air refractive index, n ET is the alcohol refractive index, n MF is the magnetic fluid refractive index, and M is the resonant order.

[0057] In the application, d1 = 37.5 μm; d2 = 25 μm.

[0058] In the application of the embodiment, the reference Figure 2 Since the magnetic fluid refractive index is sensitive to both the magnetic field and the temperature, and the alcohol refractive index is only sensitive to the temperature, when different temperatures act on the sensor, the resonant conditions of the resonant cavity filled with the magnetic fluid and the resonant cavity filled with the alcohol are both changed, and due to the same thermal-optic coefficient, the resonant wavelengths of the two resonant cavities are simultaneously shifted. Therefore, a self-reference is formed between the resonant cavity filled with the magnetic fluid and the resonant cavity filled with the alcohol. The embodiment eliminates the temperature cross-sensitivity by calculating the wavelength difference between the resonant wavelengths of the two resonant cavities. When the magnetic field acts on the sensor, the tunable refractive index of the magnetic fluid changes the resonant condition of the resonant cavity filled with the magnetic fluid, so that the resonant wavelength is shifted, while the resonant wavelength of the resonant cavity filled with the alcohol remains unchanged. A self-reference is formed between the resonant cavity filled with the magnetic fluid and the resonant cavity filled with the alcohol. The sensitivity of the sensor of the embodiment to the magnetic field is calculated by the ratio of the wavelength difference between the resonant wavelengths of the two resonant cavities to the change of the magnetic field.

[0059] Specifically, in the temperature sensing experiment, the probe of the sensor of the embodiment is fixed on a glass sheet, the two ends of the sensor are connected to a light source and a spectrum analyzer respectively, and the glass sheet with the fixed sensor probe is placed in a heating furnace. The temperature in the heating furnace is 20-80℃. When the temperature in the heating furnace is 20℃, the initial transmission spectrum is recorded. Then, the temperature in the heating furnace is increased from 20℃ to 80℃ at a step of 10℃, and the sensitivity of the sensor of the embodiment to the temperature change is recorded in turn.

[0060] Specifically, in the magnetic field sensing experiment, the probe of the sensor of the embodiment is fixed on a glass sheet, the two ends of the sensor are connected with a light source and a spectrum analyzer respectively, and the glass sheet with the fixed sensor probe is placed in a one-dimensional coil, the magnetic field of the one-dimensional coil is 100-400 Oe. When the magnetic field of the one-dimensional coil is 100 Oe, the initial transmission spectrum is recorded, then the magnetic field of the one-dimensional coil is increased from 100 Oe to 400 Oe with a step of 50 Oe, and the sensitivity of the sensor of the embodiment to the change of the magnetic field is recorded in turn.

[0061] The present application fills the two resonant cavities with alcohol and magnetic fluid respectively, so that one resonant cavity is not sensitive to the magnetic field and the other resonant cavity is sensitive to the magnetic field, thereby forming a self-reference to eliminate the temperature crosstalk in the magnetic field measurement.

[0062] In summary of the above embodiments, the present application has simple preparation process, easily available raw materials and low price, and can be widely applied in electromagnetic scientific research, power system state detection and internal and external magnetic field distribution measurement of electrical equipment.

[0063] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A method of fabricating a temperature-compensated optical fiber magnetic field sensor based on a self-referenced resonant reflective optical waveguide, characterized in that, The method comprises the following steps: obtaining a standard single-mode optical fiber, a first hollow core silica tube I and a second hollow core silica tube I, stripping the coating layers of the obtained standard single-mode optical fiber, first hollow core silica tube I and second hollow core silica tube I, and then wiping them with alcohol for standby; fusing the two ends of the standby first hollow core silica tube I and the two ends of the second hollow core silica tube I to the standard single-mode optical fiber one by one, and oppositely arranging the first hollow core silica tube I and the second hollow core silica tube I; coaxially inserting the first hollow core silica tube I fused to the standard single-mode optical fiber into the first hollow core silica tube II, and then packaging one end of the coaxial first hollow core silica tube I and the first hollow core silica tube II and placing them in alcohol, when the alcohol enters the first hollow core silica tube II and wraps the first hollow core silica tube I, packaging the other end of the coaxial first hollow core silica tube I and the first hollow core silica tube II, and forming a temperature-sensitive resonant cavity; coaxially inserting the second hollow core silica tube I fused to the standard single-mode optical fiber into the second hollow core silica tube II, and then packaging one end of the coaxial second hollow core silica tube I and the second hollow core silica tube II and placing them in magnetic fluid, when the magnetic fluid enters the second hollow core silica tube II and wraps the second hollow core silica tube I, packaging the other end of the coaxial second hollow core silica tube I and the second hollow core silica tube II, and forming a resonant cavity sensitive to both temperature and magnetic field; The inner diameter of each hollow core silica tube I is 75 μm, and the outer diameter is 150 μm; the inner diameter of each hollow core silica tube II is 240 μm, and the outer diameter is 300 μm.

2. The method of claim 1, wherein the method further comprises the step of: The length of the standard single-mode optical fiber is 1.5 cm. ​ 3. The method of claim 1, wherein the method further comprises: depositing a second layer of a second material on the first layer of the first material; and depositing a third layer of a third material on the second layer of the second material. The length of the first hollow core silica tube I and the second hollow core silica tube I is 5 mm.

4. The method of claim 1, wherein the method further comprises: depositing a second layer of a second material on the first layer of the first material; and depositing a third layer of a third material on the second layer of the second material. The distance between the first hollow core silica tube I and the second hollow core silica tube I is 1 cm.

5. A temperature-compensated optical fiber magnetic field sensor based on a self-referenced resonant reflective optical waveguide, characterized in that, The temperature-compensated optical fiber magnetic field sensor based on the self-reference resonant reflection optical waveguide is prepared by the preparation method of any one of claims 1-4.

6. The self-referenced resonant reflective optical waveguide fiber magnetic field sensor according to claim 5, wherein, The temperature-compensated optical fiber magnetic field sensor based on the self-reference resonant reflection optical waveguide comprises a single-mode optical fiber (1) and two resonant cavities (2); The two resonant cavities (2) are oppositely arranged on the single-mode optical fiber (1), one of which is only sensitive to temperature, and the other of which is sensitive to both temperature and magnetic field.

7. The self-referenced resonant reflective optical waveguide fiber magnetic field sensor according to claim 6, wherein, One resonant cavity comprises coaxially arranged first hollow core silica tube I and first hollow core silica tube II, and the space between the first hollow core silica tube I and the first hollow core silica tube II is filled with alcohol; the other resonant cavity comprises coaxially arranged second hollow core silica tube I (21) and second hollow core silica tube II (22), and the space between the second hollow core silica tube I (21) and the second hollow core silica tube II (22) is filled with magnetic fluid.

8. The self-referenced resonant reflective optical waveguide fiber magnetic field sensor according to claim 6, wherein, The distance between the oppositely arranged two resonant cavities (2) is 1 cm.

9. The self-referenced resonant reflective optical waveguide fiber magnetic field sensor according to claim 6, wherein, The length of the two resonant cavities (2) is 5 mm.

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