CN210294596U - Multi-parameter sensing multi-core optical fiber sensor - Google Patents
Multi-parameter sensing multi-core optical fiber sensor Download PDFInfo
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- CN210294596U CN210294596U CN201921349876.1U CN201921349876U CN210294596U CN 210294596 U CN210294596 U CN 210294596U CN 201921349876 U CN201921349876 U CN 201921349876U CN 210294596 U CN210294596 U CN 210294596U
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Abstract
The utility model relates to an optic fibre field, concretely relates to multicore fiber sensor of multi-parameter perception, including two at least sub-cores, surrounding layer, interior cladding and outer cladding, each sub-core comprises fibre core, inner cladding and channel layer, fibre core, inner cladding and surrounding layer are arranged according to the concentric circles structure from inside to outside, the channel layer surface is the channel structure, surrounding layer, interior cladding and outer cladding wrap up outside sub-core according to the concentric circles structure from inside to outside in proper order. The utility model discloses sub-core outside low refractive index channel structure makes the mode field better restrict in fibre core and cladding, reduces bending loss and intercore crosstalk; the outer cladding layer, the inner coating layer and the outer coating layer jointly protect the sub-core from normal and stable operation, and can prevent certain parameter changes from being difficult to conduct on the optical fiber to influence the sensing effect due to the fact that the cladding is too thick.
Description
[ technical field ] A method for producing a semiconductor device
The utility model relates to an optic fibre field especially relates to a multicore fiber sensor of many parameter perceptions.
[ background of the invention ]
At present, in the sensing field, the demand for multi-parameter sensing is increasing, and a plurality of characteristics to be measured are simultaneously influenced by a plurality of parameters. Most of the sensing optical fibers used at present are single-core optical fibers, and the influence generated by each parameter is difficult to distinguish during signal demodulation. In order to ensure that the feature to be measured is only affected by a specific parameter, it is often necessary to ensure that the other parameters in the environment where the optical fiber is located do not change significantly, which limits the sensing area and the parameter to be measured.
In order to meet the requirement of parameter sensing, a multi-core optical fiber can be used as a sensing optical fiber for sensing measurement. However, optical fibers are often used in harsh environments, and it is not practical to directly lay bare, fragile fibers. To ensure proper and stable operation of the sensing system, protection of the optical fiber as the sensor is particularly important, which relies on a jacket outside the optical fiber. In the case of optical cables, a plurality of coated optical fibers, plus a loose tube, together with reinforcing steel wires and a gel, are generally surrounded and protected from the external environment by a multi-layer composite tape, and sheath. However, too much thickness of the sheath often makes it difficult to transmit changes in some parameter to the fiber, and sensing of this parameter is not always possible. Therefore, it is necessary to design a suitable protective sheath for the optical fiber, so as to protect the optical fiber without affecting the sensing effect too much. In addition, crosstalk occurs between the multi-core fibers, which causes errors in measurement of a plurality of parameters.
In view of this, how to overcome the defects existing in the prior art, satisfy the problem of crosstalk between cores when the multi-core optical fiber is in multi-parameter sensing measurement, and avoid the problem that the parameter change cannot be sensed due to the excessively thick protective sleeve is a problem to be solved urgently in the technical field.
[ Utility model ] content
To the above defect or the improvement demand of prior art, the utility model provides a signal crosstalk and multicore optic fibre sheath are too thick to obtain the problem that the sensing parameter changes between a plurality of fibre cores of multicore.
The embodiment of the utility model provides an adopt following technical scheme:
the utility model provides a multicore fiber sensor of many parameter perceptions, including two at least sub-cores 1, surrounding layer 2, interior coating 3 and outer coating 4, sub-core 1 comprises fibre core 11, inner cladding 12 and channel layer 13, -fibre core 11, inner cladding 12 and channel layer 13 are arranged according to the concentric circles structure from inside to outside, 11 refracting indexes of fibre core are first refracting indexes, 12 refracting indexes of inner cladding are second refracting indexes, channel layer 13 refracting indexes are the third refracting indexes, first refracting indexes are greater than the second refracting indexes, the second refracting indexes are greater than the third refracting indexes, the surrounding layer 2, interior coating 3 and outer coating 4 wrap up in proper order outside sub-core 1 according to the concentric circles structure from inside to outside.
Preferably, the channel layer 13 of the sub-core 1 is a channel with a ring structure, and the channel width is not less than a preset channel width threshold.
Preferably, the refractive index difference of the core 11 of the sub-core 1 with respect to the inner cladding 12 is a first predetermined refractive index difference, the first predetermined refractive index difference is a positive value, and the refractive index difference of the channel layer 13 of the sub-core 1 with respect to the inner cladding 12 is a second predetermined refractive index difference is a negative value.
Preferably, the first predetermined refractive index difference is + 0.4%, and the second predetermined refractive index difference is-0.6%.
Preferably, the radius of the fiber core 11 of the sub-core 1 is a first preset radius, the outer radius of the inner cladding 12 is a second preset radius, and the outer radius of the channel layer 13 is a third preset radius.
Preferably, the first preset radius is 4 ± 0.5 μm, the second preset radius is 8 ± 1 μm, and the third preset radius is 12 ± 2 μm.
Preferably, one of the plurality of sub-cores 1 is located in the center of the optical fiber and is a central core 1-a, the rest of the sub-cores 1 are uniformly distributed around the central core and are peripheral cores 1-B, and the interval between the peripheral cores is not less than the preset core interval.
Preferably, the sum of the thicknesses of the outer cladding 2, the inner cladding 3 and the outer cladding 4 is not less than a predetermined thickness threshold.
Preferably, the radius of the outer cladding (2) is not more than 110 μm, the radius of the inner coating (3) is 120 μm to 130 μm, and the radius of the outer coating (4) is 440 μm to 460 μm.
Preferably, the material of the inner coating layer (3) is acrylate, and the material of the outer coating layer (4) is a copolymer of ethylene and tetrafluoroethylene.
Compared with the prior art, the utility model discloses beneficial effect lies in: the channel structure is used for preventing crosstalk among the multiple sub-fibers, the cladding and the coating are matched for use, so that the internal sub-fibers are protected, and the sensing parameter acquisition cannot be influenced due to over thickness, so that the requirement of multi-parameter sensing is met.
The utility model provides a multicore fiber sensor of many parameter perceptions, its purpose is making sensing optical fiber can measure the characteristic of awaiting measuring that receives a plurality of parameter influences, avoids the crosstalk between a plurality of sub-cores to more accurate acquisition outside sensing parameter.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below. It is obvious that the drawings described below are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be obtained from these drawings without inventive effort.
Fig. 1 is a schematic structural diagram of a multi-parameter sensing multi-core optical fiber sensor provided by an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a multi-parameter sensing multi-core optical fiber sensor sub-core provided in an embodiment of the present invention;
fig. 3 is a schematic cross-sectional structural diagram of a multi-parameter sensing multi-core optical fiber sensor provided by an embodiment of the present invention;
fig. 4 is a schematic diagram of the relationship between the core simple crosstalk and the channel layer width according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an arrangement of a multi-parameter sensor core according to an embodiment of the present invention.
[ detailed description ] embodiments
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The present invention relates to a system structure of a specific function system, and therefore, the function logic relationship of each structure module is mainly explained in the specific embodiment, and the specific software and hardware implementation modes are not limited.
Furthermore, the technical features mentioned in the embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention will be described in detail with reference to the accompanying drawings and examples.
Example 1：
With the wider application of optical fiber sensing, the multi-parameter sensing multi-core optical fiber sensor has more and more requirements. In order to enable the sensing fiber to simultaneously acquire a plurality of parameter values and distinguish the influence of each parameter, a multi-core sensing fiber is required.
The following describes the specific structure of the multi-parameter sensing multi-core optical fiber sensor of the present invention with reference to fig. 1:
referring to fig. 1, the multi-parameter sensor provided by the embodiment of the present invention includes at least two sub-cores 1, an outer cladding 2, an inner coating 3, and an outer coating 4. The outer cladding layer 2, the inner cladding layer 3 and the outer cladding layer 4 are sequentially wrapped outside the sub-core 1 from inside to outside according to a concentric circle structure. The outer periphery radius d3 of the sub-core 1, the outer periphery radius d4 of the outer cladding 2, the outer periphery radius _ d5 of the inner coating layer 3 and the outer periphery radius d6 of the outer coating layer 4.
The sensing fiber needs to measure a plurality of parameters, and therefore, a plurality of sub-cores need to be included. However, the optical fiber is delicate and fragile, and if the optical fiber is laid alone, the optical fiber is broken and damaged, and the normal and stable operation of the sensing system cannot be ensured, so that a sheath needs to be added on the outer layer. The sheath needs to provide certain strength and toughness to meet the requirements of tensile strength and bending resistance; meanwhile, the optical fiber can be prevented from being adversely affected by the external environment, and the requirements of water resistance, corrosion resistance and the like are met. However, the common communication optical fiber is wrapped and protected by ointment, steel wires, multi-layer composite belts, wrapping belts, sheaths and the like, and certain parameter transformation is difficult to transmit to the optical fiber due to the fact that the wrapping layer is too thick, and the parameters cannot be sensed. Therefore, the outer cladding layer and the two coating layers are selected as the outer protective layer of the optical fiber, so that the inner optical fiber can be protected, and the sensing parameter acquisition cannot be influenced by the excessive thickness of the wrapping layer.
As shown in fig. 2, each sub-core is composed of a core, an inner cladding and a channel layer, the core, the inner cladding and the outer cladding are arranged from inside to outside in a concentric circle structure, the outer circumference radius d1 of the core 11, the outer circumference radius 2 of the inner cladding 12 and the outer circumference radius d3 of the channel layer 13. For use in a particular usage scenario of the present embodiment, the length ratio d1: d2: d2 may be set to 1:2: 3.
When a plurality of sub-cores are used for collecting and transmitting sensing parameters together, signal crosstalk may be caused, and therefore an optical fiber with a channel structure on the outer surface is used as the sub-core. The channel structure can enable the sensing signal to be better limited in the fiber core and the inner cladding, and the bending loss of the optical fiber and the crosstalk between the cores are reduced.
In the embodiment, through the improved channel structures of the wrapping layer and the sub-cores, the sub-cores are guaranteed not to be damaged or broken, the sensing parameter signals can be correctly acquired, the signals between the sub-cores are also guaranteed not to be mutually interfered, and the multi-core optical fiber sensor capable of sensing multiple parameters is guaranteed to stably and accurately acquire and transmit the sensing parameters by combining the sub-cores and the sub-cores.
Example 2：
The multi-parameter sensing optical fiber comprises a plurality of sub-cores, and crosstalk can occur between the sub-cores or bending loss occurs at a bending part, so that a sensing signal is weakened or wrong.
In this embodiment, the outer surface of the sub-core adopts a channel structure to avoid crosstalk and weakening of sensing signals. As shown in the cross-sectional view of the multi-parameter sensing optical fiber shown in fig. 3, the refractive indexes of the fiber core 11, the inner cladding 12 and the channel layer 13 are all different, the refractive index of the fiber core 11 is the first refractive index n1, the refractive index of the inner cladding is the second refractive index n2, and the refractive index of the channel layer 13 is the third refractive index n3, where n1> n2> n 3. Due to the refractive index difference, the mode field is better confined in the core and cladding, reducing the total loss of optical signal strength in the fiber and preventing cross-talk between cores. The wider the channel width, the smaller the crosstalk between the cores, so the channel width needs to be larger than a certain value to ensure the crosstalk prevention effect.
In a specific use scenario, the preset channel width threshold is related to the sum fiber core radius of the sensing optical fiber, the refractive index difference, the core spacing, the channel width, and the like, and can be calculated by using a time domain finite difference method or a finite element method. In some usage scenarios where the above values have been determined, the relationship between the channel width and the inter-core crosstalk is shown in fig. 4, which represents the amount of inter-core crosstalk corresponding to different channel widths at an optical fiber length of 100 km. In the practical use of the optical fiber, the crosstalk introduced by the optical fiber every 1km is a fixed value, in order to reduce the crosstalk of the whole optical fiber and avoid too complicated modulation and demodulation of signals in the later period, in the specific implementation of this embodiment, it is generally required to ensure that the crosstalk between the optical fiber cores is less than-50 db/km, as shown in fig. 4, in order to ensure that the crosstalk between the cores is less than-50 db/km and ensure that the optical fiber processing process is not too complicated and the cost is not too high, the preset channel width threshold value should not be less than 4 ± 1 μm.
The channel structure needs to be matched with different interlayer refractive index differences to achieve the effect of crosstalk prevention, the refractive indexes between the fiber core 11 and the inner cladding 12 and between the inner cladding 12 and the channel layer 13 are different, the refractive index n1 of the fiber core 11 is the highest, and the refractive index n3 of the channel layer 13 is the lowest. The first predetermined refractive index difference Δ 1 of the inner cladding 12 with respect to the core 11 is positive (n1-n2)/n2, and the second predetermined refractive index difference Δ 2 of the channel layer 13 with respect to the inner cladding 12 is negative (n3-n2)/n 2. In a specific usage scenario, the first predetermined refractive index difference Δ 1 may be set to + 0.4% and the second predetermined refractive index difference Δ 2 may be set to-0.6%.
In order to improve the communication quality of the sub-core, the radius of each layer of the sub-core needs to be within a certain range. Specifically, in order to ensure the single-mode transmission quality, the first preset radius d1 can be set to be 4 ± 0.5 μm; in order to ensure the strength and the refractive index difference of the sub-core, the second preset radius d2 can be set to be 8 +/-1 mu m; to ensure the channel width and the refractive index, the third predetermined radius d3 may be set to 12 ± 2 μm.
In the embodiment, the sub-cores are arranged through the outer surface channel structure, the refractive index difference of different layers and the radius of different layers, so that crosstalk and bending loss between the cores are reduced, the signal stability of the sub-cores is improved, and the transmission accuracy of sensing data is improved.
Example 3：
The outer coating layer, the inner coating layer and the outer coating layer form a sensing optical fiber sheath. For the sheath of the sensing optical fiber, certain strength and toughness are required to protect the inner sub-core from being influenced by the outside world and not being damaged or broken, so that the sensing work stability and the data accuracy are ensured; and the thickness of the sensor can not be too thick, so that inaccurate or even unavailable acquisition of sensing parameters is avoided.
In order to distinguish different parameters in the sensing measurement, a plurality of sub-cores are used for the sensing measurement. In order to ensure that the sub-cores are uniformly distributed in the optical fiber, when n sub-cores 1 exist, 1 sub-core is placed in the center of the light to serve as a central core 1-A, and the rest n-1 sub-cores 1 are uniformly distributed around the central core 1-A to serve as a peripheral core 1-B. Specifically, in a scenario with 7 sub-cores 1, 1 sub-core is taken as a central core 1-a, and the remaining 6 sub-cores are taken as peripheral cores 1-B, and the distribution is shown in fig. 4.
Further, as shown in fig. 3, the preset core pitch may be calculated according to equation 1:
wherein Λ is a preset core pitch, d4 is a fourth preset radius, CT is the thickness of the cladding layer 2, pi is the circumferential ratio, and N is the number of peripheral cores.
In order to ensure the signal transmission quality, the distance between the peripheral cores should not be less than the preset core pitch.
Further, in some specific use scenes, in order to ensure the strength and the protection effect of the optical fiber and ensure that the optical fiber has higher outer region loss resistance, the sum of the thicknesses of the outer cladding layer 2, the inner coating layer 3 and the outer coating layer 4 is not less than a preset thickness threshold value meeting the requirement. The preset thickness threshold value is determined by the outer coating material, the manufacturing process and the like. Specifically, in some usage scenarios, the preset thickness threshold is 30 cm.
In order to ensure compact structure and manufacturing success rate of the multi-parameter sensing optical fiber, in some specific use scenes: the outer cladding 2 has a radius d4 of not more than 110 μm, optionally 112.5 μm; the radius d5 of the inner coating layer 3 is 120-130 μm, and 125 μm can be selected; the radius d6 of the outer coating 4 is 440 μm to 460. mu.m, optionally 450 μm.
In order to enhance the strength of the multi-parameter sensing optical fiber, ensure that the optical fiber is not damaged by the external environment in use, and ensure the stability of sensing measurement and communication, in some specific use scenes: the inner coating layer material is acrylic ester, has good alkali resistance and color and gloss retention, and can ensure that the optical fiber has good microbending resistance; the outer coating material is a copolymer (ETFT) of ethylene and tetrafluoroethylene, the ETFT has heat resistance, low temperature resistance, flame retardance, electrical insulation and chemical resistance, has non-adhesiveness and low friction, and can effectively prevent water vapor, fuel oil, acid and alkali and solvents from corroding the optical fiber.
The multiparameter sensing optical fiber provided by the embodiment has better environmental adaptability and compact structure through reasonable arrangement of sub-core distribution and design selection of structures and materials of all layers of the sheath, so that the optical fiber can be stably and safely applied in various different use scenes. The optical fiber damage caused by environmental factors is avoided, and the accuracy and stability of sensing data acquisition and transmission are ensured.
Claims (10)
1. A multi-parameter sensing multi-core optical fiber sensor is characterized in that: including two at least sub-cores (1), surrounding layer (2), interior coating (3) and outer coating (4), each sub-core (1) comprises fibre core (11), inner cladding (12) and channel layer (13), fibre core (11), inner cladding (12) and channel layer (13) are arranged according to the concentric circle structure from inside to outside, fibre core (11) refracting index is first refracting index, inner cladding (12) refracting index is the second refracting index, channel layer (13) refracting index is the third refracting index, first refracting index is greater than the second refracting index, the second refracting index is greater than the third refracting index, surrounding layer (2), interior coating (3) and outer coating (4) wrap up in proper order outside sub-core (1) according to the concentric circle structure from inside to outside.
2. The multi-parameter sensing multi-core fiber sensor of claim 1, wherein: the channel layer (13) of the sub-core (1) is a channel with an annular structure, and the width of the channel is not less than a preset channel width threshold value.
3. The multi-parameter sensing multi-core fiber sensor of claim 2, wherein: the refractive index difference of the fiber core (11) of the sub-core (1) relative to the inner cladding (12) is a first preset refractive index difference, the first preset refractive index difference is a positive value, the refractive index difference of the channel layer (13) of the sub-core (1) relative to the inner cladding (12) is a second preset refractive index difference, and the second preset refractive index difference is a negative value.
4. The multi-parameter sensing multi-core fiber sensor of claim 3, wherein: the first predetermined refractive index difference is + 0.4%, and the second predetermined refractive index difference is-0.6%.
5. The multi-parameter sensing multi-core fiber sensor of claim 3, wherein: the radius of a fiber core (11) of the sub-core (1) is a first preset radius, the outer radius of the inner cladding (12) is a second preset radius, and the outer radius of the channel layer (13) is a third preset radius.
6. The multi-parameter sensing multi-core fiber sensor of claim 5, wherein: the first preset radius is 4 +/-0.5 mu m, the second preset radius is 8 +/-1 mu m, and the third preset radius is 12 +/-2 mu m.
7. The multi-parameter sensing multi-core fiber sensor of claim 1, wherein: one of the at least two sub-cores (1) is positioned in the center of the optical fiber and is a middle core (1-A), the rest sub-cores (1) are uniformly distributed around the middle core and are peripheral cores (1-B), and the interval between the peripheral cores is not less than the preset core interval.
8. The multi-parameter sensing multi-core fiber sensor of claim 7, wherein: the sum of the thicknesses of the outer coating layer (2), the inner coating layer (3) and the outer coating layer (4) is not less than a preset thickness threshold value.
9. The multi-parameter sensing multi-core fiber sensor of claim 8, wherein: the radius of the outer cladding (2) is not more than 110 μm, the radius of the inner coating (3) is 120 μm-130 μm, and the radius of the outer coating (4) is 440 μm-460 μm.
10. The multi-parameter sensing multi-core fiber sensor of claim 1, wherein: the inner coating layer (3) is made of acrylic ester, and the outer coating layer (4) is made of a copolymer of ethylene and tetrafluoroethylene.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111999799A (en) * | 2020-09-18 | 2020-11-27 | 长飞光纤光缆股份有限公司 | Multi-core optical fiber |
| CN113866132A (en) * | 2021-09-26 | 2021-12-31 | 岭南师范学院 | Multichannel SPR differential intensity modulation sensor |
| CN114624812A (en) * | 2022-03-16 | 2022-06-14 | 江苏亨通光纤科技有限公司 | Multi-core energy transmission optical fiber and preparation method thereof |
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2019
- 2019-08-19 CN CN201921349876.1U patent/CN210294596U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111999799A (en) * | 2020-09-18 | 2020-11-27 | 长飞光纤光缆股份有限公司 | Multi-core optical fiber |
| CN113866132A (en) * | 2021-09-26 | 2021-12-31 | 岭南师范学院 | Multichannel SPR differential intensity modulation sensor |
| CN114624812A (en) * | 2022-03-16 | 2022-06-14 | 江苏亨通光纤科技有限公司 | Multi-core energy transmission optical fiber and preparation method thereof |
| CN114624812B (en) * | 2022-03-16 | 2024-07-02 | 江苏亨通光纤科技有限公司 | Multi-core energy-transmitting optical fiber and preparation method thereof |
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