阅读说明：本技术 一种磁场和温度同测的光纤传感器及检测方法、制作方法 (Optical fiber sensor for simultaneously measuring magnetic field and temperature, detection method and manufacturing method ) 是由 黄怿 邱荭 王廷云 邓传鲁 胡程勇 张小贝 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种磁场和温度同测的光纤传感器及检测方法、制作方法,其包括：第一段单模光纤,与空芯布拉格光纤一端相连接；空芯布拉格光纤,其内部设置于磁流体；第二段单模光纤,与所述空芯布拉格光纤的另一端相连接；获取反谐振模式；光谱检测阶段,光进入第二段单模光纤后,被光谱仪检测；将空芯布拉格光纤两端切平整,将磁流体注入空芯布拉格光纤内,将第一段单模光纤和第三段单模光纤端口切平,按第一段单模光纤、注有磁流体的空芯布拉格光纤和第二段单模光纤的结构放入熔接机中进行熔接。不仅能够实现磁场和温度同时传感,而且传感器的制作简单,经济适用性更强。(The invention discloses an optical fiber sensor for simultaneously measuring a magnetic field and temperature, a detection method and a manufacturing method, wherein the optical fiber sensor comprises the following steps: the first section of single-mode fiber is connected with one end of the hollow Bragg fiber; the hollow Bragg fiber is internally arranged in the magnetofluid; the second section of single-mode fiber is connected with the other end of the hollow Bragg fiber; acquiring an anti-resonance mode; in the spectrum detection stage, light enters the second section of single-mode fiber and is detected by a spectrometer; and cutting two ends of the hollow Bragg fiber flatly, injecting the magnetic fluid into the hollow Bragg fiber, cutting the end ports of the first section of single-mode fiber and the third section of single-mode fiber flatly, and putting the first section of single-mode fiber, the hollow Bragg fiber injected with the magnetic fluid and the second section of single-mode fiber into a fusion splicer for fusion splicing. The magnetic field and the temperature can be sensed simultaneously, and the sensor is simple to manufacture and high in economical applicability.)

1. A magnetic field and temperature co-measuring fiber optic sensor (100), characterized by: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

the first section of single-mode fiber (101) is connected with one end of the hollow Bragg fiber (102);

a hollow-core Bragg fiber (102) internally arranged in the magnetofluid (M);

and the second section of single-mode fiber (103) is connected with the other end of the hollow-core Bragg fiber (102).

2. The fiber optic sensor for simultaneous measurement of magnetic field and temperature according to claim 1, wherein: the core diameter of the first section of single-mode fiber (101) and the second section of single-mode fiber (103) is 9 mu m, the core refractive index is 1.4681, the cladding diameter is 125 mu m, and the cladding refractive index is 1.4628.

3. The fiber optic sensor for simultaneous measurement of magnetic field and temperature according to claim 1, wherein: the diameter of a fiber core of the hollow-core Bragg fiber (102) is 32 micrometers, the refractive index of the fiber core is 1, the diameter of a cladding is 125 micrometers, the cladding consists of four double claddings with high refractive indexes and low refractive indexes distributed alternately and an outermost low-folded layer, the thickness of a single high-folded layer is 1.06 micrometers, the refractive index of the high-folded layer is 1.454, the thickness of a single low-folded layer is 3.07 micrometers, the refractive index of the low-folded layer is 1.444, and the length of the hollow-core Bragg fiber (102) is set between 3mm and 1 cm.

4. The fiber optic sensor for simultaneous measurement of magnetic field and temperature according to claim 1, wherein: a broadband light source (200) emits a supercontinuum light source, enters the first section of single-mode fiber (101), and penetrates through the hollow-core Bragg fiber (102) and the second section of single-mode fiber (103);

wherein, the wavelength of the broadband light source 200 is 470 nm-2400 nm.

5. The fiber optic sensor for simultaneous measurement of magnetic field and temperature according to claim 4, wherein: light passing through the second length of single mode optical fibre (103) is detected by a spectrometer (300).

6. A method for detecting a magnetic field and temperature by using the optical fiber sensor according to claims 1 to 5, wherein: comprises the following steps of;

acquiring an anti-resonance mode;

and in the spectrum detection stage, light enters the second section of single-mode fiber and is detected by a spectrometer.

7. The method of claim 6, wherein: the first section of single-mode fiber is mismatched with the mode field of the hollow Bragg fiber, the hollow Bragg fiber is excited to form a plurality of anti-resonance modes, and light which does not meet the resonance condition of the Fabry-Perot resonant cavity is restrained in the hollow Bragg fiber and is transmitted to the second section of single-mode fiber forwards;

the anti-resonance modes mainly excited in the hollow-core bragg fiber are the LP01 mode and the LP02 mode.

8. The method of claim 6, wherein: the transmission spectrum is provided with a plurality of dip with different periods generated by anti-resonance modes in the hollow Bragg fiber, when the temperature and the magnetic field act on the sensor at the same time, the dip generated by different anti-resonance modes can generate different drifts, and the drift amounts corresponding to the magnetic field and the temperature respectively are calculated through the cross matrix, so that the double-parameter simultaneous sensing of the magnetic field and the temperature is realized.

9. A manufacturing method using the optical fiber sensor as claimed in claims 1-5 comprises: and cutting two ends of the hollow Bragg fiber flatly, injecting the magnetic fluid into the hollow Bragg fiber, cutting the end ports of the first section of single-mode fiber and the third section of single-mode fiber flatly, and putting the first section of single-mode fiber, the hollow Bragg fiber injected with the magnetic fluid and the second section of single-mode fiber into a fusion splicer for fusion splicing.

Technical Field

The invention relates to the technical field of optical fiber sensing, in particular to an optical fiber sensor for simultaneously measuring a magnetic field and temperature, a detection method and a manufacturing method.

Background

Magnetic field sensing is very important in the fields of power equipment monitoring, military engineering, biomedical engineering and the like. The optical fiber-based sensor has the characteristics of small and exquisite structure, high sensitivity, high response speed and the like, so that the optical fiber sensor is widely applied to magnetic field sensing. The magnetic fluid is used as a special functional material, and the nano-scale magnetic particles are wrapped in the surfactant and uniformly dispersed in the base liquid to form a stable colloidal solution; the magnetic fluid has both liquid fluidity and the magneto-refraction characteristic of magnetic materials, so that the magnetic fluid is often used as a magneto-sensitive material to be combined with an optical fiber sensor and used for magnetic field measurement. When the magnetic field intensity changes, the refractive index of the magnetic fluid changes, so that the transmission spectrum of the sensor drifts, and the magnetic field measurement can be completed by observing the wavelength drift amount of the transmission spectrum. However, the refractive index of the magnetic fluid changes along with the change of the magnetic field, and the change of the temperature also causes the change of the refractive index of the magnetic fluid. Therefore, in order to obtain more accurate measurement results, the magnetic field and the temperature need to be measured simultaneously.

The hollow-core optical fiber based on anti-resonance reflection guidance can inject magnetic fluid into the optical fiber due to the unique structure of the hollow-core optical fiber, so that the purpose of increasing the sensing sensitivity is achieved. The cladding of the hollow-core Bragg fiber consists of four pairs of double claddings and one low-refractive outermost cladding, and the multi-cladding structure enables light transmitted in the hollow-core Bragg fiber to be more bound in the fiber.

Disclosure of Invention

This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.

The invention is provided in view of the problems of the existing optical fiber sensor and detection method based on simultaneous measurement of magnetic field and temperature.

Therefore, the invention aims to provide an optical fiber sensor and a detection method based on simultaneous measurement of magnetic field and temperature.

In order to solve the technical problems, the invention provides the following technical scheme: the first section of single-mode fiber is connected with one end of the hollow Bragg fiber; the hollow Bragg light is internally arranged in the magnetic fluid; and the second section of single-mode fiber is connected with the other end of the hollow Bragg fiber.

As a preferable scheme of the optical fiber sensor based on simultaneous measurement of magnetic field and temperature, the optical fiber sensor comprises: the fiber core diameter of the first section of single mode fiber and the second section of single mode fiber is 9 microns, the fiber core refractive index is 1.4681, the cladding diameter is 125 microns, and the cladding refractive index is 1.4628.

As a preferable scheme of the optical fiber sensor based on simultaneous measurement of magnetic field and temperature, the optical fiber sensor comprises: the core diameter of the hollow core Bragg fiber is 32 mu m, the core refractive index is 1, the cladding diameter is 125 mu m, the cladding consists of four double claddings with high refractive index and low refractive index alternately distributed and an outermost low-folding layer, the thickness of a single high-folding layer is 1.06 mu m, the refractive index of the high-folding layer is 1.454, the thickness of a single low-folding layer is 3.07 mu m, the refractive index of the low-folding layer is 1.444, and the length of the hollow core Bragg fiber 203 is set between 3mm and 1 cm.

As a preferable scheme of the optical fiber sensor based on simultaneous measurement of magnetic field and temperature, the optical fiber sensor comprises: a broadband light source emits a super-continuous light source, enters the first section of single-mode fiber and penetrates through the hollow Bragg fiber and the second section of single-mode fiber; wherein, the wavelength of the broadband light source 200 is 470 nm-2400 nm.

As a preferred embodiment of the optical fiber sensor and the detection method based on simultaneous measurement of magnetic field and temperature, the present invention further comprises: light passing through the second section of single mode optical fiber is detected by a spectrometer.

In order to solve the technical problems, the invention also provides the following technical scheme: acquiring an anti-resonance mode; and in the spectrum detection stage, light enters the second section of single-mode fiber and is detected by a spectrometer.

As a preferable scheme of the method for detecting magnetic field and temperature based on the optical fiber sensor, the method comprises the following steps: the first section of single-mode fiber is mismatched with the mode field of the hollow Bragg fiber, the hollow Bragg fiber is excited to form a plurality of anti-resonance modes, and light which does not meet the resonance condition of the Fabry-Perot resonant cavity is restrained in the hollow Bragg fiber and is transmitted to the second section of single-mode fiber forwards; the anti-resonance modes mainly excited in the hollow-core bragg fiber are the LP01 mode and the LP02 mode.

As a preferable scheme of the method for detecting magnetic field and temperature based on the optical fiber sensor, the method comprises the following steps: the transmission spectrum is provided with a plurality of dip with different periods generated by anti-resonance modes in the hollow Bragg fiber, when the temperature and the magnetic field act on the sensor at the same time, the dip generated by different anti-resonance modes can generate different drifts, and the drift amounts corresponding to the magnetic field and the temperature respectively are calculated through the cross matrix, so that the double-parameter simultaneous sensing of the magnetic field and the temperature is realized.

In order to solve the technical problems, the invention also provides the following technical scheme: and cutting two ends of the hollow Bragg fiber flatly, injecting the magnetic fluid into the hollow Bragg fiber, cutting the end ports of the first section of single-mode fiber and the third section of single-mode fiber flatly, and putting the first section of single-mode fiber, the hollow Bragg fiber injected with the magnetic fluid and the second section of single-mode fiber into a fusion splicer for fusion splicing.

The invention has the beneficial effects that: the magnetic field and the temperature can be sensed simultaneously, and the sensor is simple to manufacture.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:

fig. 1 is a schematic overall structure diagram of an optical fiber sensor and a detection method based on simultaneous measurement of magnetic field and temperature according to the present invention.

Fig. 2 is a transverse interface diagram of the hollow bragg fiber after magnetic fluid injection according to the optical fiber sensor and the detection method based on simultaneous measurement of magnetic field and temperature.

Fig. 3 is a detection schematic diagram of a magnetic field and temperature dual-parameter sensor with a three-section structure according to the optical fiber sensor and the detection method for simultaneously detecting a magnetic field and a temperature of the invention.

Fig. 4 is a transmission spectrum of the anti-resonance mode LP01 mode in the hollow-core bragg fiber according to the optical fiber sensor and the detection method based on simultaneous measurement of magnetic field and temperature in the present invention.

Fig. 5 is a transmission spectrum of the anti-resonance mode LP02 mode in the hollow-core bragg fiber according to the optical fiber sensor and the detection method based on simultaneous measurement of magnetic field and temperature in the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

Furthermore, the present invention is described in detail with reference to the drawings, and in the detailed description of the embodiments of the present invention, the cross-sectional view illustrating the structure of the device is not enlarged partially according to the general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

Example 1

Referring to fig. 1 to 4, an optical fiber sensor 100 based on simultaneous measurement of magnetic field and temperature includes a first section of single mode fiber 101 connected to one end of a hollow-core bragg fiber 102; a hollow-core bragg fiber 102, the interior of which is disposed in the magnetic fluid M; and a second section of single mode fiber 103 connected to the other end of the hollow core bragg fiber 102.

Specifically, the core diameter of the first section of single-mode fiber 101 and the second section of single-mode fiber 103 is 9 μm, the core refractive index is 1.4681, the cladding diameter is 125 μm, and the cladding refractive index is 1.4628; the core diameter of the hollow-core Bragg fiber 102 is 32 mu m, the core refractive index is 1, the cladding diameter is 125 mu m, the cladding consists of four double claddings with high refractive index and low refractive index which are alternately distributed and an outermost low-refractive index, the thickness of a single high-refractive index is 1.06 mu m, the refractive index of the high-refractive index is 1.454, the thickness of a single low-refractive index is 3.07 mu m, the refractive index of the low-refractive index is 1.444, and the hollow-core Bragg fiber 203 is set between 3mm and 1 cm. This data is derived from laboratory experiments and based on this parameter the device can be implemented, otherwise it cannot be guaranteed that the device is valid.

Further, the broadband light source 200 emits a super-continuum light source, enters the first section of single-mode fiber 101, passes through the hollow-core bragg fiber 102 and the second section of single-mode fiber 103, and is finally detected by the spectrometer 300.

Wherein, the wavelength of the broadband light source 200 is 470 nm-2400 nm.

Example 2

Referring to fig. 1 to 5, a method for detecting both magnetic field and temperature includes a light-entering stage and a spectrum-ready detecting stage.

After light emitted by the broadband light source enters the first section of single-mode fiber, the light enters the hollow-core Bragg fiber through the transmission of the first section of single-mode fiber, when the first section of single-mode fiber, the second section of single-mode fiber and the hollow-core Bragg fiber are subjected to center alignment fusion and the fiber core of the hollow-core Bragg fiber is not collapsed, the fusion joint can excite anti-resonance modes in a plurality of hollow-core Bragg fibers, the most important modes are the LP01 mode and the LP02 mode, and different anti-resonance modes have different sensitivities to the change of the external environment.

The hollow Bragg fiber is an optical fiber guided based on an antiresonance reflection mechanism, a cladding layer of the hollow Bragg fiber is equivalent to a Fabry-Perot resonant cavity, most of light meeting the resonance condition of the Fabry-Perot resonant cavity in the optical fiber can leak to the cladding layer and the outside, light not meeting the resonance condition of the Fabry-Perot resonant cavity can be well constrained in a fiber core and transmitted forwards, and the light passes through the hollow Bragg fiber and is coupled into a second section of single-mode fiber to be detected by a spectrometer.

In particular, there are multiple groups of dip with different periods in the transmission spectrum, each group of dip being caused by an anti-resonant mode in the hollow-core bragg fiber. The transmission spectrum is mainly formed by the cooperation of the LP01 mode and the LP02 mode, and dip with different periods in the transmission spectrum corresponds to an anti-resonance mode. When an external magnetic field or temperature changes, the refractive index of the magnetic fluid injected into the hollow-core Bragg fiber changes, so that the refractive index of a cladding of the hollow-core Bragg fiber changes, spectral lines in a transmission spectrum drift, and dip corresponding to different anti-resonance modes have different wavelength drift amounts.

The resonant wavelength of a hollow core bragg fiber can be given by:

where d is the thickness of the hollow-core bragg fiber cladding, ne is the normalized effective refractive index of the hollow-core bragg fiber cladding, n0 is the core refractive index of the hollow-core bragg fiber, and m is the resonance order.

When the temperature and the magnetic field act on the sensor at the same time, different drifts can occur to dip produced by different anti-resonance modes, and the variation quantity corresponding to the magnetic field and the temperature can be calculated through a cross matrix, so that the double-parameter simultaneous sensing of the magnetic field and the temperature is realized.

Example 3

A method for manufacturing a sensor for simultaneously measuring magnetic field and temperature comprises cutting, injecting and welding.

Before use, the hollow Bragg fiber is cleaned by alcohol, coating residues on the surface are wiped off, and two ends of the hollow Bragg fiber are cut flat by a cutter, so that better fusion joint with the first section of single-mode fiber and the third section of single-mode fiber is ensured; then, the magnetic fluid is injected into the hollow Bragg fiber by utilizing the capillary effect of the hollow Bragg fiber, and only a small amount of magnetic fluid needs to be injected because the undiluted magnetic fluid has strong light absorption and strong sensitivity to a magnetic field; and finally, putting the first section of single-mode fiber, the second section of single-mode fiber and the hollow Bragg fiber injected with the magnetic fluid into a fusion splicer, and carrying out manual center alignment fusion splicing according to the structures of the first section of single-mode fiber, the hollow Bragg fiber and the second section of single-mode fiber.

After a small amount of magnetic fluid is injected into the hollow-core Bragg fiber, when the hollow-core Bragg fiber is welded with the first section of single-mode fiber and the second section of single-mode fiber, the magnetic fluid in the hollow-core Bragg fiber can move due to the discharging heat effect of the welding machine and can be attached to the inner wall of the hollow-core Bragg fiber finally, and the magnetic fluid is equivalent to an inner cladding of the hollow-core Bragg fiber at the moment.

It is important to note that the construction and arrangement of the present application as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in this application. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of this invention. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present inventions. Therefore, the present invention is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims.

Moreover, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not be described (i.e., those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the invention).

It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.