WO2020244034A1 - 一种多芯少模光纤及其制造方法 - Google Patents

一种多芯少模光纤及其制造方法 Download PDF

Info

Publication number
WO2020244034A1
WO2020244034A1 PCT/CN2019/096641 CN2019096641W WO2020244034A1 WO 2020244034 A1 WO2020244034 A1 WO 2020244034A1 CN 2019096641 W CN2019096641 W CN 2019096641W WO 2020244034 A1 WO2020244034 A1 WO 2020244034A1
Authority
WO
WIPO (PCT)
Prior art keywords
core
layer
flow rate
core layer
few
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2019/096641
Other languages
English (en)
French (fr)
Inventor
杜城
罗文勇
李伟
陈保平
何茂友
胡国华
钱峰
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ruiguang Telecommunication Technologies Co Ltd
Fiberhome Telecommunication Technologies Co Ltd
Original Assignee
Ruiguang Telecommunication Technologies Co Ltd
Fiberhome Telecommunication Technologies Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ruiguang Telecommunication Technologies Co Ltd, Fiberhome Telecommunication Technologies Co Ltd filed Critical Ruiguang Telecommunication Technologies Co Ltd
Priority to EP19931680.3A priority Critical patent/EP3982175B1/en
Publication of WO2020244034A1 publication Critical patent/WO2020244034A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02042—Multicore optical fibres
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
    • G01L1/246—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre using integrated gratings, e.g. Bragg gratings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
    • G02B6/0365—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - - +
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03661—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 4 layers only

Definitions

  • the invention relates to the field of optical fiber sensing and optical fiber communication, in particular to a multi-core and few-mode optical fiber and a manufacturing method thereof.
  • Fiber Bragg grating (Fiber Bragg Grating) sensor has high environmental adaptability and long-term reliability, and has the advantages of micron size, soft and light weight, and convenient implantation. It is a mature distributed structural health long-term monitoring technology.
  • One of the current research hotspots of flexible skin composite materials is to embed the grating-engraved optical fiber into composite materials to form a smart skin structure, thereby realizing long-term damage monitoring of the wing skin.
  • traditional optical fiber sensors are based on conventional single The core communication fiber has the characteristics of being sensitive to axial direction and insensitive to lateral deformation. Therefore, special layout is required to meet the needs of bending sensing.
  • Multi-core fiber has multiple high refractive index cores, so multi-core grating formed by grating is written on multi-core fiber, which can effectively combine the bending sensing characteristics of multi-core fiber with the strain sensitive characteristics of grating and the advantages of distributed measurement .
  • sensor fiber grating arrays without solder joints are widely used to monitor the deformation of aircraft skins.
  • the manufacturing process of multi-core optical fiber with a structure is relatively difficult.
  • the currently used multi-core optical fiber core is usually a combination of multiple identical simple step waveguides. The transmission signals are similar and difficult to distinguish.
  • This type of multi-core with similar waveguide structure Optical fiber is also not conducive to data analysis in subsequent optical fiber grating writing effect inspection and monitoring applications.
  • the multi-core optical fiber 1 includes a plurality of core units 10a, 10b, 10c and a plurality of second cores 21.
  • the core unit 10a includes a first core 11a and an inner cladding in turn 12a and the low refractive index layer 13a
  • the core unit 10b sequentially includes a first core 11b, an inner cladding 12b, and a low refractive index layer 13b
  • the core unit 10c sequentially includes a first core 11c, an inner cladding 12c and a low refractive index
  • the outer peripheral surface of the low-refractive-index layer 13c and the low-refractive index layers 13a, 13b and 13c are all surrounded by the outer cladding 30.
  • the multi-core fiber 1 is provided with four layers of LY1, LY2, LY3 and LY4, and multiple cores on each layer They are all distributed regularly in a hexagonal shape, and the effective refractive indexes of the core units 10a, 10b, and 10c and the second core 21 are different.
  • This multi-core optical fiber 1 solves the problem of suppressing crosstalk during signal transmission by satisfying a specific arrangement rule and changing the refractive index.
  • the manufacturing process of this type of fiber is complicated, and the arrangement and accuracy are high.
  • the number of fiber cores is large and symmetrically distributed, which can only be used in the communication field, not in the sensor. , The scope of application is limited.
  • the purpose of the present invention is to provide a multi-core and few-mode optical fiber and a manufacturing method thereof, which solves the problem of similar and indistinguishable signals in the signal transmission process when the optical fiber is applied in the field of sensing and communication. problem.
  • the fiber body includes at least one first fiber core and at least two second fiber cores arranged at a predetermined distance from the center of the fiber body and at least two second fiber cores, each of the first fiber core and the second fiber core includes at least one
  • the recirculation layer includes three core layers, and a core layer is also provided outside the recirculation layer.
  • the refractive index or diameter of any two adjacent core layers of the first core and the second core Different, wherein at least one of the effective refractive index and the diameter of the first core is different from the second core;
  • the refractive index of the cladding is lower than the effective refractive index of the first core and the second core, and higher than the first core And the refractive index of the outermost core layer of the second core.
  • the circulation layer includes a first core layer, a second core layer and a third core layer arranged in order from the inside to the outside, and the core layer located outside the circulation layer is the fourth core layer,
  • the maximum relative refractive index difference between the first core layer and the third core layer is 0.3% to 2.5%
  • the minimum relative refractive index difference is 0.05% to 0.6%.
  • the relative refractive index difference is 0% to 1.1%.
  • the refractive index of the third core layer is greater than or equal to the refractive index of the cladding layer, and the refractive index of the fourth core layer, the cladding layer and the third core layer are approximately step distributions .
  • the distribution power index ⁇ of the refractive index of the first core layer is -1.2 to -2.5.
  • both the first core and the second core include a plurality of circulating layers arranged in sequence, and the fourth core layer is arranged outside the outermost circulating layer.
  • the predetermined distance is 32-248 ⁇ m.
  • the number of the first core is 3 at most.
  • the slim body further includes a coating layer, and the coating layer is provided on the outside of the coating layer.
  • the thickness of the coating layer is 20-100 m, and the radius of the cladding layer is 30-500 m.
  • the coating layer is one of double-layer acrylic resin, polyimide, single-layer acrylic resin or silicone rubber.
  • the purpose of the present invention is to provide a method for manufacturing a multi-core and few-mode optical fiber, which solves the problem that the transmission signal is similar and difficult to distinguish in the signal transmission process when the optical fiber is applied in the field of sensing and communication.
  • deposition materials including silicon tetrachloride SiCl 4 , germanium tetrachloride GeCl 4 , phosphorus oxychloride BCl 3 , hexafluoroethane C 2 F 6 and oxygen O 2 are used in the quartz reaction tube to deposit four layers from the outside to the inside.
  • the relative refractive index difference and the radius ratio between the core layers of each layer are adjusted by respectively adjusting the flow ratio of the deposition material and the number of deposition passes;
  • the quartz tube is made into a solid rod, drill holes are drilled at different predetermined positions of the solid rod, and a plurality of the solid core rods are ground and processed into the holes of the solid rod and melted to form a
  • the multi-core structure few-mode optical fiber preform is drawn to form a multi-core structure few-mode optical fiber.
  • the four-layer core layer includes a first core layer, a second core layer, a third core layer and a fourth core layer arranged from the inside to the outside, wherein:
  • the flow rate of SiCl 4 is controlled to be 50-85%, the flow rate of GeCl 4 is 10-20%, the flow rate of BCl 3 is 10-30%, and C 2 F 6
  • the flow rate of O 2 is 0-10%, the flow rate of O 2 is 30-70%, and the number of deposition passes is 600-4800;
  • the flow rate of SiCl 4 is controlled to be 30-70%, the flow rate of GeCl 4 is 0-20%, the flow rate of C 2 F 6 is 10-40%, and O 2
  • the flow rate ratio is 30-70%, and the number of deposition passes is 200-1200;
  • the flow rate of SiCl 4 is controlled to be 30 to 70%, the flow rate of GeCl 4 is 20 to 75%, the flow rate of C 2 F 6 is 0 to 25%, and O 2
  • the flow rate is 30-70%, and the number of deposition passes is 300-1200;
  • control the flow rate of SiCl 4 to 50-85%, the flow rate of GeCl 4 to 10-20%, the flow rate of BCl 3 to 10-30%, and the C 2 F 6 The flow rate of O 2 is 0-10%, the flow rate of O 2 is 30-70%, and the number of deposition passes is 200-6000.
  • the predetermined positions respectively correspond to the positions of the first core and the second core at a predetermined distance from the center of the fiber body.
  • the core layer is deposited by plasma chemical vapor deposition method.
  • a multi-core and few-mode optical fiber provided by the present invention includes two ring-shaped core structures with graded refractive index. Each core includes four core layers with different refractive indexes or diameters. Each core Both can support multiple linear polarization modes, which can meet the needs of shape sensing. While satisfying grating array writing, the distinction between different linear polarization modes ensures simple identification of transmission signals from different cores and reduces the resolution of three-dimensional shape sensing signals. Adjust the difficulty and improve the lateral deformation sensitivity of FBG sensors based on multi-core optical fibers on the basis of satisfying applications in the communication field.
  • the special multi-gradient waveguide structure that facilitates the transmission of low-order mode signals can reduce the leakage and crosstalk of optical signals in the case of microbending and overall shape bending caused by compressive stress in the shape sensing application of multi-core fibers.
  • Multi-core structure few-mode fiber has good optical performance and reliability, and has excellent multi-mode transmission performance, which meets the needs of shape sensing applications.
  • a multi-core and few-mode optical fiber provided by the present invention is made by plasma chemical vapor deposition process, which directly realizes the ring-core-type waveguide structure matching the design, and each core is on the basis of meeting the predetermined center distance.
  • the above can be set arbitrarily, and the requirements for the distribution accuracy of the cores in the multi-core structure and the few-mode fiber are relatively low, and the requirements for parallel comparison of multi-dimensional channels for multi-directional shape sensing can be easily met, effectively solving the problem of multiple cores. Doping at specific locations to achieve the problem of ring-shaped core structure.
  • Figure 1 is a schematic diagram of the structure of a multi-core optical fiber in the prior art
  • FIG. 2 is a schematic diagram of the structure of a multi-core and few-mode optical fiber in an embodiment of the present invention
  • FIG. 3 is a schematic structural diagram of a first core of a multi-core and few-mode optical fiber in an embodiment of the present invention
  • FIG. 4 is a schematic diagram of the longitudinal section of the first core of the multi-core few-mode optical fiber in the embodiment of the present invention.
  • n(r) is the power index-law refractive index distribution function
  • n 1 is the refractive index at the axis of the multi-core and few-mode fiber
  • r is the distance between the outer side of each core layer and the axis of the multi-core and few-mode fiber
  • a is the radius of the whole multi-core and few-mode fiber
  • ⁇ is the distribution power exponent
  • ⁇ is the relative refractive index difference, where a>r, A ⁇ 0.
  • an embodiment of the present invention provides a multi-core and few-mode optical fiber, including a fiber body and a cladding 3.
  • the fiber body includes at least one first fiber that is spaced apart from the center of the fiber body by a predetermined distance.
  • the core 1 and at least two second cores 2, the first core 1 and the second core 2, and every two second cores 2 are spaced apart, the first core 1 and the second core 2
  • Each includes at least one recirculation layer, the recirculation layer includes three core layers, and a core layer is provided outside the recirculation layer.
  • the refractive index or diameter of any two adjacent core layers of the first core 1 and the second core 2 Different, wherein at least one of the effective refractive index and diameter of the first core 1 is different from that of the second core 2, so that the first core 1 and the second core 2 have different mode lengths during the transmission of optical signals.
  • both the first core 1 and the second core 2 can support multiple linear polarization modes and orbital angular momentum modes for transmission.
  • the cladding 3 has a certain thickness and surrounds the first core 1 and the second core 2, so that the first core 1 and the second core 2 are embedded in the cladding 3.
  • the refractive index of the cladding 3 is low
  • the effective refractive index of the first core 1 and the second core 2 is higher than the refractive index of the outermost core layer of the first core 1 and the second core 2.
  • the circulating layer includes a first core layer 11, a second core layer 12 and a third core layer 13 arranged in order from the inside to the outside, and the core layer located outside the circulating layer is the fourth core layer 14.
  • the first core layer 11 is located at the exact center of the core and has a cylindrical shape.
  • the second core layer 12, the third core layer 13, and the fourth core layer 14 extend from the inside to the outside along the outer surface of the first core layer 11. Layers are arranged to form the whole core. Among them, the maximum relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.3% to 1.8%, and the minimum relative refractive index difference is 0.05% to 0.6%.
  • the third core layer 13 and the second core layer 12 are The relative refractive index difference is 0.2% to 1.2%, and the relative refractive index difference between the third core layer 13 and the fourth core layer 14 is 0% to 1.1%.
  • the refractive index of the third core layer 13 is greater than or equal to the refractive index of the cladding layer 3, and the refractive index of the fourth core layer 14, the cladding layer 3 and the third core layer 13 are approximately stepped distributions ,
  • the distribution power index of the refractive index of the first core layer 11 is -1.2 to -2.5.
  • the effective refractive index or diameter of the first core 1 and the second core 2 will affect the mode length of the transmitted light, and the different mode length can solve the problem of signal identification when different cores transmit signals. Therefore, the first At least one of the effective refractive index or the diameter of the one core 1 and the second core 2 is different from each other.
  • the effective refractive index of the first core 1 and the second core 2 is affected by the refractive index of any core layer or the thickness of the core layer, where the thickness of the core layer here refers to the difference between the inner and outer radii of the annular core layer Therefore, by adjusting the refractive index or core thickness of each core layer.
  • each core layer of the first core 1 and the second core 2 have the same value range, but the specific values are different to ensure that the first core 1 and the second core 2 At least one of the effective refractive index or the diameter is different from each other, which can effectively identify the signal when transmitting the signal.
  • the slimming body also includes a coating layer 4, which is provided on the outside of the coating layer 3.
  • the coating layer 4 can be a double layer of acrylic resin, polyimide, a single layer of acrylic or silicone rubber.
  • the radius of the cladding layer 3 of the multi-core and few-mode fiber is 30-500 ⁇ m
  • the thickness of the coating layer 4 is 20-100 ⁇ m.
  • the thickness here refers to the distance between the inner and outer surfaces of the coating layer 4.
  • the multi-core and few-mode fiber has two different cores, and the cores are separated by a certain distance. They are set arbitrarily on the basis of a predetermined distance from the fiber body.
  • the effective refractive index or diameter between the two different cores at least one different, such that the multi-core few mode fiber can support LP 01, LP 02, LP 11 , LP 21, LP 31 mode five linearly polarized, and in addition to the LP 01, LP 02, LP 11 , LP 21, LP 31
  • the linear polarization mode and other modes except OAM 0 , OAM ⁇ 1 and OAM ⁇ 2 have a loss per meter greater than 20dB.
  • the exponential function distribution of multi-core and few-mode fibers with a scale factor of less than zero effectively increases the mode-mode coupling and reduces the difficulty of MIMO calculation in long-distance transmission, making the transmission loss of the supported modes less than 0.20 at 1550nm wavelength dB/km.
  • the cut-off wavelength of the multi-core and few-mode fiber in other linear polarization modes such as LP 41 is less than 1500nm.
  • the performance parameters of the multi-core and few-mode fiber are as follows:
  • the predetermined distance between the first core 1 and the second core 2 from the center of the fiber body is 32-248 ⁇ m, and on the basis of ensuring that each core is arranged at intervals, the first core 1 and the second core 2
  • the distance from the center of the fiber body can be arbitrarily selected within the range of a predetermined distance of 32-248 ⁇ m and then set at any position.
  • the structure is simple and the manufacturing is convenient.
  • both the first core 1 and the second core 2 include a plurality of circulation layers arranged in sequence, and the fourth core layer 14 is arranged outside the outermost circulation layer. After a plurality of circulation layers are arranged, the number of circulation layers is more regular. This superposition can realize the increase of stable transmission mode.
  • the number of the first core 1 is 3 at most.
  • the number of the first core 1 is 3 at most.
  • the possible combinations of the first core 1 and the second core 2 are 1+2, 1+3, 2+5, 3+ 4 wait.
  • the present invention also provides a method for manufacturing a multi-core and few-mode optical fiber.
  • the technical solution adopted is that firstly, silicon tetrachloride SiCl 4 , germanium tetrachloride GeCl 4 , phosphorus oxychloride BCl 3 , and six
  • the deposition materials of fluoroethane C 2 F 6 and oxygen O 2 respectively deposit four core layers from the outside to the inside, and during the deposition process, the deposition materials SiCl 4 , GeCl 4 , BCl 3 , C 2 F 6 and
  • the flow ratio of O 2 and the number of passes of each layer are used to adjust the relative refractive index difference and radius ratio between the core layers of each layer; since the quartz reaction tube is a hollow reaction tube before deposition, after the deposition of four core layers, There is still a hollow area in the center of the deposited quartz reaction tube, so it needs to be melted, so after the deposition is completed, the deposited quartz reaction tube is melted into a solid core rod
  • a plurality of manufactured solid core rods are put into the holes of the solid rod and melted to make the deposited
  • the outer layer of the quartz reaction tube is fused with the inner layer of the solid rod made of quartz tube to form a multi-core and few-mode fiber preform corresponding to the first core 1 or the second core 2; finally, the multi-core and few-mode fiber preform is made Wire drawing to produce a multi-core structure few-mode fiber that meets the requirements.
  • the predetermined positions respectively correspond to the positions of the first core 1 and the second core 2 at a predetermined distance from the center of the fiber body, and the distance between the predetermined position and the center of the fiber body is within a predetermined distance range.
  • the plasma chemical vapor deposition method is used to deposit each core layer.
  • the four core layers include a first core layer 11, a second core layer 12, a third core layer 13, and a first core layer 11 arranged from the inside to the outside Four-core layer 14, wherein during the deposition of the fourth core layer 14, the flow rate of SiCl 4 is controlled to be 50-85%, the flow rate of GeCl 4 is 10-20%, and the flow rate of BCl 3 is 10-30 %, the flow rate of C 2 F 6 is 0-10%, the flow rate of O 2 is 30-70%, and the number of deposition passes is 600-4800; in the process of depositing the third core layer 13, control the SiCl 4 The flow rate is 30-70%, the flow rate of GeCl 4 is 0-20%, the flow rate of C 2 F 6 is 10-40%, the flow rate of O 2 is 30-70%, and the number of deposition passes is 200-1200.
  • the flow rate of SiCl 4 is controlled to be 30 to 70%, the flow rate of GeCl 4 is 20 to 75%, the flow rate of C 2 F 6 is 0 to 25%, O 2
  • the flow rate of SiCl 4 is controlled to be 50-85%, and the flow rate of GeCl 4 is 10-20%.
  • the flow rate of BCl 3 is 10-30%, the flow rate of C 2 F 6 is 0-10%, the flow rate of O 2 is 30-70%, and the number of deposition passes is 200-6000.
  • the flow rate of O 2 is 55%, and the number of deposition passes is 650.
  • the flow rate of SiCl 4 is controlled to 35%, the flow rate of GeCl 4 is 20%, and the flow rate of C 2 F 6
  • the flow rate ratio of O 2 is 10%, the flow rate of O 2 is 60%, and the number of deposition passes is 200.
  • the flow rate of SiCl 4 is controlled to 35%, and the flow rate of GeCl 4 is 75 %, the flow rate of C 2 F 6 is 0%, the flow rate of O 2 is 50%, and the number of deposition passes is 320; in the process of depositing the first core layer 11, the flow rate of SiCl 4 is controlled to 50%, GeCl The flow rate of 4 is 18%, the flow rate of BCl 3 is 10%, the flow rate of C 2 F 6 is 0%, the flow rate of O 2 is 70%, and the number of deposition passes is 300.
  • the corresponding structure parameters of the multi-core and few-mode fiber are as follows, the distance between the first core 1 and the center of the fiber body is 35 ⁇ m, the distance between the second core 2 and the center of the fiber body is 35 ⁇ m, the first core 1 and The distance between the second core 2 and every two second cores 2 is 49.5 ⁇ m.
  • the maximum value ⁇ %max of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 1.8%
  • the minimum value ⁇ %min of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.35.
  • the distribution power index ⁇ of the first core layer 11 is -1.87, and the relative refractive index difference ⁇ % between the third core layer 13 and the fourth core layer 14 is 0.11%.
  • the radius D 1 of the first core layer 11 is 2.2 m
  • the radius of the second core 12 is D 2 is 3.2 m
  • the radius of the third core layer 13 is 3 D is 3.6 m
  • the fourth core of radius D 4 14 It is 4.8 ⁇ m.
  • the diameter of the cladding layer 3 of the multi-core and few-mode fiber is 125 ⁇ m
  • the diameter of the coating layer 4 is 245 ⁇ m.
  • the flow rate of O 2 is 50%, and the number of deposition passes is 620.
  • the flow rate of SiCl 4 is controlled to 35%, the flow rate of GeCl 4 is 0%, and C 2 F 6
  • the flow rate ratio of O 2 is 40%, the flow rate of O 2 is 60%, and the number of deposition passes is 300.
  • the flow rate of SiCl 4 is controlled to 30%, and the flow rate of GeCl 4 is 25 %, the flow rate of C 2 F 6 is 20%, the flow rate of O 2 is 60%, and the number of deposition passes is 380; in the process of depositing the first core layer 11, the flow rate of SiCl 4 is controlled to 60%, GeCl The flow rate of 4 is 15%, the flow rate of BCl 3 is 25%, the flow rate of C 2 F 6 is 10%, the flow rate of O 2 is 65%, and the number of deposition passes is 320.
  • the structure parameters of the multi-core and few-mode fiber corresponding to this method are as follows, the distance between the first core 1 and the center of the fiber body is 45 ⁇ m, the distance between the second core 2 and the center of the fiber body is 45 ⁇ m, and the first core 1 The distance from the second core 2 and every two second cores 2 is 77.9 ⁇ m.
  • the maximum value ⁇ %max of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.70%, and the minimum value ⁇ %min of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.15 %, and the distribution power index ⁇ of the first core layer 11 is -1.85, and the relative refractive index difference ⁇ % between the third core layer 13 and the fourth core layer 14 is 0.04%.
  • the radius D1 of the first core layer 11 is 2.3 ⁇ m
  • the radius D2 of the second core layer 12 is 3.3 ⁇ m
  • the radius D3 of the third core layer 13 is 4.0 ⁇ m
  • the radius D4 of the fourth core layer 14 is 5.1 ⁇ m.
  • the diameter of the cladding layer 3 of the multi-core and few-mode fiber is 125 ⁇ m, and the diameter of the coating layer 4 is 245 ⁇ m.
  • the main performance and corresponding performance parameters of the multi-core and few-mode fiber corresponding to this embodiment are shown in Table 2:
  • the structure parameters of the multi-core and few-mode fiber corresponding to this method are as follows, the distance between the first core 1 and the center of the fiber body is 40 ⁇ m, the distance between the second core 2 and the center of the fiber body is 40 ⁇ m, and the first core 1 The distance from the second core 2 and every two second cores 2 is 69.2 ⁇ m.
  • the maximum value ⁇ %max of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 1.56%
  • the minimum value ⁇ %min of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.30 %
  • the distribution power index ⁇ of the first core layer 11 is -1.92
  • the relative refractive index difference ⁇ % between the third core layer 13 and the fourth core layer 14 is 0.10%.
  • the radius D 1 of the first core layer 11 is 9.5 ⁇ m
  • the radius D 2 of the second core layer 12 is 10.2 ⁇ m
  • the radius D 3 of the third core layer 13 is 11.7 ⁇ m
  • the radius D 4 of the fourth core layer 14 It is 13.7 ⁇ m.
  • the diameter of the cladding layer 3 of the multi-core and few-mode fiber is 250 ⁇ m, and the diameter of the coating layer 4 is 400 ⁇ m.
  • the main performance and corresponding performance parameters of the multi-core and few-mode fiber corresponding to this embodiment are shown in Table 3:
  • the flow rate of O 2 is 60%, and the number of deposition passes is 4700.
  • the flow rate of SiCl 4 is controlled to 60%, the flow rate of GeCl 4 is 10%, and C 2 F 6
  • the flow rate of SiCl 4 is 37%, the flow rate of O 2 is 50%, and the number of deposition passes is 1150.
  • the flow rate of SiCl 4 is controlled to 65% and the flow rate of GeCl 4 is 25 %, the flow rate of C 2 F 6 is 20%, the flow rate of O 2 is 65%, and the number of deposition passes is 1100; in the process of depositing the first core layer 11, the flow rate of SiCl 4 is controlled to 80%, GeCl The flow rate of 4 is 12%, the flow rate of BCl 3 is 25%, the flow rate of C 2 F 6 is 10%, the flow rate of O 2 is 65%, and the number of deposition passes is 5500.
  • the structure parameters of the multi-core and few-mode fiber corresponding to this method are as follows, the distance between the first core 1 and the center of the fiber body is 45 ⁇ m, the distance between the second core 2 and the center of the fiber body is 45 ⁇ m, and the first core 1 The distance from the second core 2 and every two second cores 2 is 77.94 ⁇ m.
  • the maximum value ⁇ %max of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.32%, and the minimum value ⁇ %min of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.13.
  • the distribution power index ⁇ of the first core layer 11 is -1.91, and the relative refractive index difference ⁇ % between the third core layer 13 and the fourth core layer 14 is 0.03%.
  • the radius D 1 of the first core layer 11 is 9.4 ⁇ m
  • the radius D 2 of the second core layer 12 is 11.1 ⁇ m
  • the radius D 3 of the third core layer 13 is 14.1 ⁇ m
  • the radius D 4 of the fourth core layer 14 It is 28.2 ⁇ m.
  • the diameter of the cladding layer 3 of the multi-core and few-mode fiber is 250 ⁇ m
  • the diameter of the coating layer 4 is 400 ⁇ m.
  • control the flow rate of SiCl 4 to 55%, GeCl 4 to 20%, BCl 3 to 10%, and C 2 F 6 to 2% In the process of depositing the fourth core layer 14, control the flow rate of SiCl 4 to 55%, GeCl 4 to 20%, BCl 3 to 10%, and C 2 F 6 to 2%.
  • the flow rate of O 2 is 50%, and the number of deposition passes is 800; in the process of depositing the third core layer 13, the flow rate of SiCl 4 is controlled to 65%, the flow rate of GeCl 4 is 10%, and C 2 F 6
  • the flow rate ratio of O 2 is 15%, the flow rate ratio of O 2 is 55%, and the number of deposition passes is 300.
  • the flow ratio of SiCl 4 is controlled to 60%, and the flow ratio of GeCl 4 is 25 %, the flow rate of C 2 F 6 is 22%, the flow rate of O 2 is 70%, and the number of deposition passes is 900; in the process of depositing the first core layer 11, the flow rate of SiCl 4 is controlled to 80%, GeCl The flow rate of 4 is 15%, the flow rate of BCl 3 is 20%, the flow rate of C 2 F 6 is 10%, the flow rate of O 2 is 55%, and the number of deposition passes is 1500.
  • the structure parameters of the multi-core and few-mode fiber corresponding to this method are as follows.
  • the distance between the first core 1 and the center of the fiber body is 32 ⁇ m
  • the distance between the second core 2 and the center of the fiber body is 32 ⁇ m
  • the first core 1 The distance from the second core 2 and every two second cores 2 is 45.3 ⁇ m.
  • the maximum value ⁇ %max of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.35%
  • the minimum value ⁇ %min of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.32.
  • the distribution power index ⁇ of the first core layer 11 is -1.92, and the relative refractive index difference ⁇ % between the third core layer 13 and the fourth core layer 14 is 0.11%.
  • the radius D 1 of the first core layer 11 is 4.9 ⁇ m
  • the radius D 2 of the second core layer 12 is 6.2 ⁇ m
  • the radius D 3 of the third core layer 13 is 6.6 ⁇ m
  • the radius D 4 of the fourth core layer 14 It is 7.5 ⁇ m.
  • the diameter of the cladding layer 3 of the multi-core and few-mode fiber is 125 ⁇ m
  • the diameter of the coating layer 4 is 245 ⁇ m.
  • Table 5 the main performance and corresponding performance parameters of the multi-core and few-mode fiber corresponding to this embodiment are shown in Table 5.
  • the flow rate of O 2 is 70%, and the number of deposition passes is 4200.
  • the flow rate of SiCl 4 is controlled to 35%, the flow rate of GeCl 4 is 20%, and the flow rate of C 2 F 6
  • the flow rate ratio of O 2 is 35%, the flow rate of O 2 is 65%, and the number of deposition passes is 600
  • the flow ratio of SiCl 4 is controlled to 35%, and the flow ratio of GeCl 4 is 55 %, the flow rate of C 2 F 6 is 2%, the flow rate of O 2 is 50%, and the number of deposition passes is 850
  • the flow rate of SiCl 4 is controlled to 75%, GeCl
  • the flow rate of 4 is 15%, the flow rate of BCl 3 is 20%, the flow rate of C 2 F 6 is 5%, the flow rate of O 2 is 55%, and the number of deposition passes is 4500.
  • the structure parameters of the multi-core and few-mode fiber corresponding to this method are as follows, the distance between the first core 1 and the center of the fiber body is 60 ⁇ m, the distance between the second core 2 and the center of the fiber body is 60 ⁇ m, and the first core 1 The distance from the second core 2 and every two second cores 2 is 103.92 ⁇ m.
  • the maximum value ⁇ %max of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 1.32%
  • the minimum value ⁇ %min of the relative refractive index difference between the first core layer 11 and the third core layer 13 is 0.14 %
  • the distribution power index ⁇ of the first core layer 11 is -1.92
  • the relative refractive index difference ⁇ % between the third core layer 13 and the fourth core layer 14 is 0.04%.
  • the radius D 1 of the first core layer 11 is 8.5 ⁇ m
  • the radius D 2 of the second core layer 12 is 9.2 ⁇ m
  • the radius D 3 of the third core layer 13 is 9.7 ⁇ m
  • the radius D 4 of the fourth core layer 14 It is 12.7 ⁇ m.
  • the diameter of the cladding layer 3 of the multi-core and few-mode fiber is 250 ⁇ m, and the diameter of the coating layer 4 is 350 ⁇ m.
  • the main performance and corresponding performance parameters of the multi-core and few-mode fiber corresponding to this embodiment are shown in Table 6:
  • the flow rate of O 2 is 70%, and the number of deposition passes is 620.
  • the flow rate of SiCl 4 is controlled to 55%, the flow rate of GeCl 4 is 5%, and C 2 F 6
  • the flow rate of SiCl 4 is 25%, the flow rate of O 2 is 60%, and the number of deposition passes is 300.
  • the flow rate of SiCl 4 is controlled to 35%, and the flow rate of GeCl 4 is 75 %, the flow rate of C 2 F 6 is 2%, the flow rate of O 2 is 50%, and the number of deposition passes is 350; in the process of depositing the first core layer 11, the flow rate of SiCl 4 is controlled to be 55%, GeCl The flow rate of 4 is 15%, the flow rate of BCl 3 is 10%, the flow rate of C 2 F 6 is 4%, the flow rate of O 2 is 50%, and the number of deposition passes is 270.
  • the corresponding structure parameters of the multi-core and few-mode fiber are as follows.
  • the distance between the first core 1 and the center of the fiber body is 20 ⁇ m
  • the distance between the second core 2 and the center of the fiber body is 20 ⁇ m
  • the first core 1 and The distance between the second core 2 and every two second cores 2 is 34.64 ⁇ m.
  • the maximum relative refractive index difference ⁇ %max of the first core layer 11 and the third core layer 13 is 2.5%
  • the minimum relative refractive index difference ⁇ %min of the first core layer 11 and the third core layer 13 is 0.18 %
  • the distribution power index ⁇ of the first core layer 11 is -1.91
  • the relative refractive index difference ⁇ % between the third core layer 13 and the fourth core layer 14 is 0.05%
  • the radius D 1 of the first core layer 11 is 2.1 ⁇ m
  • the radius D 2 of the second core layer 12 is 3.1 ⁇ m
  • the radius D 3 of the third core layer 13 is 3.8 ⁇ m
  • the radius D 4 of the fourth core layer 14 It is 5.0 ⁇ m.
  • the diameter of the cladding layer 3 of the multi-core and few-mode fiber is 80 ⁇ m, and the diameter of the coating layer 4 is 165 ⁇ m.
  • the main performance and corresponding performance parameters of the multi-core and few-mode fiber corresponding to this embodiment are shown in Table 7:
  • the flow rate of O 2 is 55%, and the number of deposition passes is 4800.
  • the flow rate of SiCl 4 is controlled to be 65%
  • the flow rate of GeCl 4 is 8%
  • the flow rate of C 2 F 6 is controlled.
  • the flow rate ratio of O 2 is 10%, the flow rate of O 2 is 50%, and the number of deposition passes is 1200; in the process of depositing the second core layer 12, the flow rate of SiCl 4 is controlled to 65%, and the flow rate of GeCl 4 is 50 %, the flow rate of C 2 F 6 is 25%, the flow rate of O 2 is 65%, and the number of deposition passes is 1100; in the process of depositing the first core layer 11, the flow rate of SiCl 4 is controlled to 85%, GeCl The flow rate of 4 is 12%, the flow rate of BCl 3 is 30%, the flow rate of C 2 F 6 is 10%, the flow rate of O 2 is 70%, and the number of deposition passes is 5900.
  • the structure parameters of the multi-core and few-mode fiber corresponding to this method are as follows.
  • the distance between the first core 1 and the center of the fiber body is 175 ⁇ m
  • the distance between the second core 2 (third and fourth) and the center of the fiber body is both
  • the distance between the first core 1 and the second core 2 and every two second cores 2 is 247.49 ⁇ m.
  • the maximum relative refractive index difference ⁇ %max of the first core layer 11 and the third core layer 13 is 0.65%
  • the minimum relative refractive index difference ⁇ %min of the first core layer 11 and the third core layer 13 is 0.22 %
  • the distribution power index ⁇ of the first core layer 11 is -1.89
  • the relative refractive index difference ⁇ % between the third core layer 13 and the fourth core layer 14 is 0.06%
  • the radius D 1 of the first core layer 11 is 9.69 ⁇ m
  • the radius D 2 of the second core layer 12 is 10.56 ⁇ m
  • the radius D 3 of the third core layer 13 is 11.42 ⁇ m
  • the radius D 4 of the fourth core layer 14 It is 14.38 ⁇ m.
  • the diameter of the cladding 3 of the multi-core and few-mode optical fiber is 850 ⁇ m, and the diameter of the coating layer 4 is 1000 ⁇ m.
  • the main performance and corresponding performance parameters of the multi-core and few-mode fiber corresponding to this embodiment are shown in Table 8.
  • the flow rate of O 2 is 70%, and the number of deposition passes is 2000.
  • the flow rate of SiCl 4 is controlled to 65%, the flow rate of GeCl 4 is 16%, and the flow rate of C 2 F 6 is controlled.
  • the flow rate ratio of O 2 is 22%, the flow rate of O 2 is 40%, and the number of deposition passes is 800.
  • the flow rate of SiCl 4 is controlled to 60%, and the flow rate of GeCl 4 is 70 %, the flow rate of C 2 F 6 is 20%, the flow rate of O 2 is 60%, and the number of deposition passes is 900; in the process of depositing the first core layer 11, the flow rate of SiCl 4 is controlled to 80%, GeCl The flow rate of 4 is 15%, the flow rate of BCl 3 is 20%, the flow rate of C 2 F 6 is 10%, the flow rate of O 2 is 50%, and the number of deposition passes is 3500.
  • the structure parameters of the multi-core and few-mode fiber corresponding to this method are as follows.
  • the distance between the first core 1 and the center of the fiber body is 62 ⁇ m, and the distance between the second core and the center of the fiber body is 62 ⁇ m.
  • the distance between the three cores 2 and every two second cores 2 is 100.32 ⁇ m.
  • the maximum relative refractive index difference ⁇ %max of the first core layer 11 and the third core layer 13 is 0.98%
  • the minimum relative refractive index difference ⁇ %min of the first core layer 11 and the third core layer 13 is 0.19 %
  • the distribution power index ⁇ of the first core layer 11 is -1.90
  • the relative refractive index difference ⁇ % between the third core layer 13 and the fourth core layer 14 is 0.05%.
  • the radius D 1 of the first core layer 11 is 7.4 m
  • the radius of the second core 12 is D 2 is 8.3 m
  • the radius of the third core layer 13 is 3 D is 9.1 m
  • the fourth core of radius D 4 14 It is 10.7 ⁇ m.
  • the diameter of the cladding layer 3 of the multi-core and few-mode fiber is 250 ⁇ m, and the diameter of the coating layer 4 is 350 ⁇ m.
  • the main performance and corresponding performance parameters of the multi-core and few-mode fiber corresponding to this embodiment are shown in Table 9:
  • the present invention is not limited to the above-mentioned best embodiment.
  • anyone can derive other products in various forms under the enlightenment of the present invention, but regardless of any changes in its shape or structure, any product that is the same or similar to the present invention All technical solutions are within the scope of protection.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)
  • Optical Couplings Of Light Guides (AREA)

Abstract

一种多芯少模光纤及其制造方法，多芯少模光纤包括纤体和包层（3），纤体包括有距纤体中心预定距离且相互间隔设置的至少一根第一纤芯（1）和至少两根第二纤芯（2），第一纤芯（1）和第二纤芯（2）均包括至少一循环层和设于循环层外侧的芯层，第一纤芯（1）和第二纤芯（2）任意相邻两层芯层的折射率或直径不同，第一纤芯（1）的有效折射率和直径中的至少一种与第二纤芯（2）不同，包层（3）包围第一纤芯（1）和第二纤芯（2），包层（3）的折射率低于第一纤芯（1）和第二纤芯（2）的有效折射率，高于第一纤芯（1）和第二纤芯（2）最外侧芯层的折射率。解决了光纤在传感及通信领域应用时，信号传输过程中传输信号相似而难以区分的问题。

Description

一种多芯少模光纤及其制造方法 技术领域
本发明涉及光纤传感与光纤通信领域，具体涉及一种多芯少模光纤及其制造方法。
背景技术
未来飞行器中，采用柔性变形机翼的变体飞行器是一个重要的发展方向，而集驱动控制和传感监测于一体的智能复合材料结构成为飞行器新型柔性蒙皮的首选，对于高端变体机翼的变形监测，二维变形数据已经无法满足未来飞行器的要求，实时获得机翼的三维空间变形数据显得极为重要。因此亟待研究开发新一代的监测技术，对未来飞行器变形机翼的三维空间变形进行实时动态监测，提供准确的变形数据，为飞行器的安全飞行提供重要保障。
光纤布拉格光栅(Fiber Bragg Grating)传感器具有较高的环境适应性和长期可靠性，且有微米尺寸、柔软质轻、植入方便等优点，是一种成熟的分布式结构健康长期监测技术。目前柔性蒙皮复合材料的研究热点之一是将刻有光栅的光纤埋植到复合材料中形成智能蒙皮结构，进而实现机翼蒙皮的长期损伤监测，然而传统的光纤传感器均基于常规单芯通信光纤，具有对轴向敏感、侧向变形不敏感的特点，因此需要进行特别布设才可以满足弯曲传感的需求。
多芯光纤因具有多个高折射率纤芯，因此在多芯光纤上写制光栅形成的多芯光栅，可有效结合多芯光纤的弯曲传感特性和光栅的应变敏感特性及分布式测量优势。当前普遍采用无焊点的传感光纤光栅阵 列用于飞行器蒙皮变形的监测，在光纤光栅制造与应用过程中，对多芯结构光纤主体的各芯区进行有效区分尤其重要，而由于不同芯结构的多芯光纤制造工艺难度较大，当前应用的多芯光纤纤芯通常为多个相同简单阶跃型波导的组合，其传输信号相似而难以区分，这类各芯波导结构相似的多芯光纤，也不利于后续光纤光栅刻写效果检验与监测应用中的数据分析。
如附图1所示的多芯光纤，多芯光纤1包括多个纤芯单元10a、10b、10c和多个第2纤芯21，纤芯单元10a依次包括第一纤芯11a、内侧包层12a和低折射率层13a,纤芯单元10b依次包括第一纤芯11b、内侧包层12b和低折射率层13b,纤芯单元10c依次包括第一纤芯11c、内侧包层12c和低折射率层13c,低折射率层13a、13b和13c的外周面均被外侧包层30包围，多芯光纤1内设有LY1、LY2、LY3和LY4四层，每一层上的多根纤芯均按照六边形的形状规律分布，纤芯单元10a、10b和10c与第2纤芯21的有效折射率不同。此多芯光纤1通过满足特定排列规律以及变换折射率从而解决了信号传输过程中抑制交扰的问题。然而其依然存在问题，首先，此类光纤的制作工艺复杂，对排列及精度要求高，其次，纤芯的根数较多且呈对称分布，只能应用在通信领域，而不能应用在传感器上，应用范围有限。
发明内容
针对现有技术中存在的缺陷，本发明的目的在于提供一种多芯少模光纤及其制造方法，解决了光纤在传感及通信领域应用时，信号传输过程中传输信号相似而难以区分的问题。
为达到以上目的，本发明采取的技术方案是：
纤体，其包括有距所述纤体中心预定距离且相互间隔设置的至少 一根第一纤芯和至少两根第二纤芯，所述第一纤芯和第二纤芯均包括至少一循环层，所述循环层包括三层芯层，且所述循环层的外侧还设有一层芯层，所述第一纤芯和第二纤芯任意相邻两层芯层的折射率或直径不同，其中，所述第一纤芯的有效折射率和直径中的至少一种与所述第二纤芯不同；
包层，其包围所述第一纤芯和第二纤芯，所述包层的折射率低于所述第一纤芯和第二纤芯的有效折射率，高于所述第一纤芯和第二纤芯最外侧芯层的折射率。
在上述技术方案的基础上，所述循环层包括从内至外依次设置的第一芯层、第二芯层和第三芯层，位于所述循环层外侧的芯层为第四芯层，其中，所述第一芯层与第三芯层的最大相对折射率差为0.3％～2.5％，最小相对折射率差为0.05％～0.6％，所述第三芯层与第四芯层的相对折射率差为0％～1.1％。
在上述技术方案的基础上，所述第三芯层的折射率大于或等于所述包层的折射率，所述第四芯层、包层和第三芯层的折射率为近似阶跃分布。
在上述技术方案的基础上，所述第一芯层的折射率的分布幂指数α为-1.2～-2.5。
在上述技术方案的基础上，所述第一纤芯和第二纤芯均包括多个依次设置的循环层，所述第四芯层设于最外侧的所述循环层外。
在上述技术方案的基础上，所述预定距离为32～248μm。
在上述技术方案的基础上，所述第一纤芯的根数最多为3根。
在上述技术方案的基础上，所述纤体还包括涂覆层，所述涂覆层设于所述包层的外侧。
在上述技术方案的基础上，所述涂覆层的厚度为20～100μm，所 述包层的半径为30～500μm。
在上述技术方案的基础上，所述涂覆层为双层丙烯酸树脂、聚酰亚胺、单层丙烯酸树或硅橡胶中的一种。
另一方面，本发明的目的在于提供一种多芯少模光纤的制造方法，解决了光纤在传感及通信领域应用时，信号传输过程中传输信号相似而难以区分的问题。
为达到以上目的，本发明采取的技术方案是：
在石英反应管内采用包括四氯化硅SiCl 4、四氯化锗GeCl 4、三氯氧磷BCl 3、六氟乙烷C 2F 6和氧气O 2的沉积原料从外至内分别沉积四层芯层，在沉积过程中，通过分别调整所述沉积原料的流量比例以及沉积的趟数来调节各层所述芯层之间的相对折射率差和半径比；
将沉积后的所述石英反应管在2000℃以上的温度下熔缩成实心芯棒；
设定不同的沉积原料的流量比例以及沉积的趟数来制备多根与第一纤芯和第二纤芯对应的实心芯棒；
将石英管制成实心棒，在所述实心棒的不同预定位置钻孔，并将多根所述实心芯棒磨制加工后放入至所述实心棒的孔洞中并进行熔缩，形成与所述第一纤芯或第二纤芯对应的多芯结构少模光纤预制棒；
对所述多芯结构少模光纤预制棒进行拉丝，制成多芯结构少模光纤。
在上述技术方案的基础上，所述四层芯层包括从内至外设置的第一芯层、第二芯层、第三芯层和第四芯层，其中，
在沉积所述第四芯层的过程中，控制SiCl 4的流量比例为50～85％，GeCl 4的流量比例为10～20％，BCl 3的流量比例为10～30％，C 2F 6的流量比例为0～10％，O 2的流量比例为30～70％，沉积趟数为600～4800 趟；
在沉积所述第三芯层的过程中，控制SiCl 4的流量比例为30～70％，GeCl 4的流量比例为0～20％，C 2F 6的流量比例为10～40％，O 2的流量比例为30～70％，沉积趟数200～1200趟；
在沉积所述第二芯层的过程中，控制SiCl 4的流量比例为30～70％，GeCl 4的流量比例为20～75％，C 2F 6的流量比例为0～25％，O 2的流量比例为30～70％，沉积趟数300～1200趟；
在沉积所述第一芯层的过程中，控制SiCl 4的流量比例为50～85％，GeCl 4的流量比例为10～20％，BCl 3的流量比例为10～30％，C 2F 6的流量比例为0～10％，O 2的流量比例为30～70％，沉积趟数为200～6000趟。
在上述技术方案的基础上，所述预定位置分别与距所述纤体中心预定距离的所述第一纤芯和第二纤芯的位置对应。
在上述技术方案的基础上，采用等离子体化学气相沉积法来沉积所述芯层。
与现有技术相比，本发明的优点在于：
(1)本发明提供的一种多芯少模光纤，包括2种均具有渐变折射率的环形纤芯结构，每根纤芯包括具有不同折射率或直径的四层芯层，每根纤芯均能支持多个线性偏振模式，能够契合形状传感需求，在满足光栅阵列刻写的同时，通过不同线偏振模式的区分，保障不同纤芯传输信号的简单辨识，降低三维形状传感信号的解调难度，在满足通信领域应用的基础上，提升基于多芯光纤的FBG传感器侧向变形敏感性。另外，利于低阶模式信号传输的特殊多梯度波导结构，能够降低多芯光纤在形状传感应用环节中，在因压应力造成的微弯和整体形状弯曲的情况下的光信号的泄露与串扰，多芯结构少模光纤具备 良好的光学性能与可靠性，具备优良的多个模式传输性能，契合形状传感应用需求。
(2)本发明提供的一种多芯少模光纤，利用等离子体化学气相沉积工艺制成，直接实现了与设计匹配的环形纤芯式波导结构，各根纤芯在满足预定中心距离的基础上可以任意设置，对于多芯结构少模光纤中纤芯的分布精度要求较低，能较容易的满足多方向形状传感需求的多个维度信道并行对比需求，有效解决了多个纤芯中特定位置掺杂实现环形纤芯结构的难题。
附图说明
图1为现有技术中多芯光纤的结构示意图；
图2为本发明实施例中的多芯少模光纤的结构示意图；
图3为本发明实施例中的多芯少模光纤的第一纤芯的结构示意图；
图4为本发明实施例中的多芯少模光纤的第一纤芯的纵截面的示意图。
图中：1-第一纤芯，11-第一芯层，12-第二芯层，13-第三芯层，14-第四芯层，2-第二纤芯，3-包层，4-涂覆层。
具体实施方式
以下结合附图对本发明的实施例作进一步详细说明。
为了方便理解，首先对本发明涉及的专业术语如相对折射率差进行解释，其定义如下：
Figure PCTCN2019096641-appb-000001
这里n i和n 0分别为各芯层和包层3在1550nm波长时的折射率， i＝1,2,3,4，i的取值分别与第一芯层11，第二芯层12，第三芯层13和第四芯层14对应。
Figure PCTCN2019096641-appb-000002
其中，n(r)为幂指数律折射率分布函数，n 1为多芯少模光纤的轴心处的折射率，r为各个芯层的外侧面距离多芯少模光纤轴心的距离，a为整根多芯少模光纤的半径，α为分布幂指数，Δ为相对折射率差，其中，a＞r，A＜0。
参见图2所示，本发明实施例提供一种多芯少模光纤，包括纤体和包层3，具体地，纤体包括有距纤体中心预定距离且相互间隔设置的至少一根第一纤芯1和至少两根第二纤芯2，第一纤芯1和第二纤芯2以及每两根第二纤芯2之间均间隔设置，第一纤芯1和第二纤芯2均包括至少一循环层，循环层包括三层芯层，且循环层的外侧还设有一层芯层，第一纤芯1和第二纤芯2任意相邻两层芯层的折射率或直径不同，其中，第一纤芯1的有效折射率和直径中的至少一种与第二纤芯2不同，使第一纤芯1和第二纤芯2在传输光信号的过程中模长不一样，以保证不同纤芯传输信号的简单辨识，满足使用要求，这里第一纤芯1和第二纤芯2均可以支持多个线偏振模式与轨道角动量模式传输。包层3具有一定的厚度且包围第一纤芯1和第二纤芯2，使第一纤芯1和第二纤芯2嵌设于包层3内，这里，包层3的折射率低于第一纤芯1和第二纤芯2的有效折射率，高于第一纤芯1和第二纤芯2最外侧芯层的折射率。
参见图3所示，循环层包括从内至外依次设置的第一芯层11、第二芯层12和第三芯层13，位于循环层外侧的芯层为第四芯层14。具体地，第一芯层11位于纤芯的正中心，且呈圆柱状，第二芯层12、第三芯层13和第四芯层14沿第一芯层11的外侧面从内至外层层设 置，构成纤芯整体。其中，第一芯层11与第三芯层13的最大相对折射率差为0.3％～1.8％，最小相对折射率差为0.05％～0.6％，第三芯层13与第二芯层12的相对折射率差为0.2％～1.2％，第三芯层13与第四芯层14的相对折射率差为0％～1.1％。
参见图2-图3所示，第三芯层13的折射率大于或等于包层3的折射率，第四芯层14、包层3和第三芯层13的折射率为近似阶跃分布，第一芯层11的折射率的分布幂指数为-1.2～-2.5。
其中，第一纤芯1和第二纤芯2的有效折射率或者直径不同均会影响传输光的模长，而不同的模长可以解决不同纤芯传输信号时的信号辨识问题，因此，第一纤芯1与第二纤芯2的有效折射率或者直径中的至少一种彼此不同。第一纤芯1和第二纤芯2的有效折射率受任意一层芯层的折射率或芯层厚度影响，其中这里的芯层的厚度是指呈环形的芯层的内外半径的差值，因此，通过调节每一芯层的折射率或芯层厚度即可。这里的第一纤芯1和第二纤芯2的每一层芯层的折射率和厚度的取值范围均相同，但是具体取值有差异，保证第一纤芯1与第二纤芯2的有效折射率或者直径中的至少一种彼此不同，能够在传输信号时将信号有效的辨识。
参见图2所示，纤体还包括涂覆层4，涂覆层4设于包层3的外侧，涂覆层4可以为双层丙烯酸树脂、聚酰亚胺、单层丙烯酸树或硅橡胶中的一种，多芯少模光纤的包层3的半径为30～500μm，涂覆层4的厚度为为20～100μm，这里的厚度是指涂覆层4的内外面的距离。多芯少模光纤具有两种不同的纤芯，且纤芯之间间隔一定距离，在距离纤体预定距离的基础上任意设置，两种不同的纤芯之间的有效折射率或直径中的至少一种不同，使得多芯少模光纤可以支持LP 01、LP 02、LP 11、LP 21、LP 31五个线偏振模式，且对除了LP 01、LP 02、LP 11、LP 21、 LP 31线偏振模式及OAM 0、OAM ±1、OAM ±2以外的其他模式的每米损耗均大于20dB。多芯少模光纤的比例系数小于零的指数函数分布纤芯有效增大了模式与模式耦合，降低了长距离传输中的MIMO计算难度，使得其所支持模式的传输损耗在1550nm波长处小于0.20dB/km。另外，多芯少模光纤在LP 41等其他线偏振模式的截止波长小于1500nm，多芯少模光纤性能实现参数如下表：
支持模式 LP 01/LP 02/LP 11/LP 21/LP 31/OAM1阶/OAM2阶/OAM0阶
LP 01衰减系数(dB/km) 0.188
LP 02衰减系数(dB/km) 0.24
LP 11衰减系数(dB/km) 0.192
LP 21衰减系数(dB/km) 0.21
LP 31衰减系数(dB/km) 0.23
具体的，第一纤芯1和第二纤芯2距纤体中心的预定距离为32～248μm，及在保证每根纤芯间隔设置的基础上，第一纤芯1和第二纤芯2距纤体中心的距离可以取在预定距离32～248μm的范围内任意取值后在任意位置设置，相比于对于位置关系要求严格的纤芯来说，结构简单，制作方便。
进一步的，第一纤芯1和第二纤芯2均包括多个依次设置的循环层，第四芯层14设于最外侧的循环层外，设置多个循环层后，这样按规律的多个叠加可以实现稳定传输模式的增加。
进一步的，第一纤芯1的根数最多为3根。当应用在传感器上时，由于纤芯过多会影响其传输性能，因此，纤芯的根数不宜过多，优选的总数最多不超过7根。这里第一纤芯1的根数最多为3根，一根光纤内，第一纤芯1和第二纤芯2一般可能的数量组合为1+2、1+3、2+5、3+4等等。
本发明还提供一种多芯少模光纤的制造方法，采取的技术方案为，首先在石英反应管内采用包括四氯化硅SiCl 4、四氯化锗GeCl 4、三氯氧磷BCl 3、六氟乙烷C 2F 6和氧气O 2的沉积原料从外至内分别沉积四层芯层，并且在沉积过程中，通过分别调整沉积原料SiCl 4、GeCl 4、BCl 3、C 2F 6和O 2的流量比例以及每层沉积的趟数来调节各层芯层之间的相对折射率差和半径比；由于石英反应管在没有沉积之前为空心反应管，在沉积四层芯层后，沉积后的石英反应管的中心依然存在空心区域，因此需要进行熔缩，于是在沉积结束后，将沉积后的石英反应管在2000℃以上的温度下熔缩成实心芯棒；随后根据设计的需求，设定不同的沉积原料的流量比例以及沉积的趟数来制备多根与第一纤芯1和第二纤芯2对应的实心芯棒；多根实心芯棒制作完成后，再将石英管熔缩成制成实心棒，并在实心棒的不同预定位置钻孔，将多根制作好的实心芯棒磨制加工后放入至实心棒的孔洞中并进行熔缩，使沉积后的石英反应管的外层与石英管制成的实心棒的内层融合，形成与第一纤芯1或第二纤芯2对应的多芯少模光纤预制棒；最后对多芯少模光纤预制棒进行拉丝，制成符合要求的多芯结构少模光纤。
具体的，预定位置分别与距纤体中心预定距离的第一纤芯1和第二纤芯2的位置对应，及预定位置与纤体中心的距离在预定距离范围内。
进一步的，采用等离子体化学气相沉积法来沉积各层芯层，具体的，四层芯层包括从内至外设置的第一芯层11、第二芯层12、第三芯层13和第四芯层14，其中，在沉积第四芯层14的过程中，控制SiCl 4的流量比例为50～85％，GeCl 4的流量比例为10～20％，BCl 3的流量比例为10～30％，C 2F 6的流量比例为0～10％，O 2的流量比例为30～70％，沉积趟数为600～4800趟；在沉积第三芯层13的过程中， 控制SiCl 4的流量比例为30～70％，GeCl 4的流量比例为0～20％，C 2F 6的流量比例为10～40％，O 2的流量比例为30～70％，沉积趟数200～1200趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为30～70％，GeCl 4的流量比例为20～75％，C 2F 6的流量比例为0～25％，O 2的流量比例为30～70％，沉积趟数300～1200趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为50～85％，GeCl 4的流量比例为10～20％，BCl 3的流量比例为10～30％，C 2F 6的流量比例为0～10％，O 2的流量比例为30～70％，沉积趟数为200～6000趟。
下面结合具体的实施例对本发明做出进一步详细的说明。
实施例1
本实施例中提供的传感用多芯结构少模光纤的制造方法具体为：
在沉积第四芯层14的过程中，控制SiCl 4的流量比例为52％，GeCl 4的流量比例为20％，BCl 3的流量比例为10％，C 2F 6的流量比例为0％，O 2的流量比例为55％，沉积趟数为650趟；在沉积第三芯层13的过程中，控制SiCl 4的流量比例为35％，GeCl 4的流量比例为20％，C 2F 6的流量比例为10％，O 2的流量比例为60％，沉积趟数200趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为35％，GeCl 4的流量比例为75％，C 2F 6的流量比例为0％，O 2的流量比例为50％，沉积趟数320趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为50％，GeCl 4的流量比例为18％，BCl 3的流量比例为10％，C 2F 6的流量比例为0％，O 2的流量比例为70％，沉积趟数为300趟。
与此对应的多芯少模光纤的结构参数如下，第一纤芯1距纤体中心的距离均为35μm，第二纤芯2距纤体中心的距离均为35μm，第一纤芯1和第二纤芯2及每两根第二纤芯2之间的距离均为49.5μm。其中，第一芯层11与第三芯层13的相对折射率差最大值Δ％max为 1.8％，第一芯层11与第三芯层13的相对折射率差最小值Δ％min为0.35％，且第一芯层11的分布幂指数α为-1.87，第三芯层13与第四芯层14的相对折射率差Δ％为0.11％。另外，第一芯层11的半径D 1为2.2μm，第二芯层12的半径D 2为3.2μm，第三芯层13的半径D 3为3.6μm，第四芯层14的半径D 4为4.8μm。与此对应的多芯少模光纤的包层3的直径为125μm，涂覆层4的直径为245μm。其中，本实施例对应的多芯少模光纤的主要性能和对应的性能参数如表1所示：
表1 实施例1的多芯少模光纤的主要性能和对应的性能参数
Figure PCTCN2019096641-appb-000003
实施例2
本实施例中提供的传感用多芯结构少模光纤的制造方法具体为：
在沉积第四芯层14的过程中，控制SiCl 4的流量比例为65％，GeCl 4的流量比例为11％，BCl 3的流量比例为28％，C 2F 6的流量比例 为10％，O 2的流量比例为50％，沉积趟数为620趟；在沉积第三芯层13的过程中，控制SiCl 4的流量比例为35％，GeCl 4的流量比例为0％，C 2F 6的流量比例为40％，O 2的流量比例为60％，沉积趟数300趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为30％，GeCl 4的流量比例为25％，C 2F 6的流量比例为20％，O 2的流量比例为60％，沉积趟数380趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为60％，GeCl 4的流量比例为15％，BCl 3的流量比例为25％，C 2F 6的流量比例为10％，O 2的流量比例为65％，沉积趟数为320趟。
与此方法对应的多芯少模光纤的结构参数如下，第一纤芯1距纤体中心的距离均为45μm，第二纤芯2距纤体中心的距离均为45μm，第一纤芯1和第二纤芯2及每两根第二纤芯2之间的距离均为77.9μm。其中，第一芯层11与第三芯层13的相对折射率差最大值Δ％max为0.70％，第一芯层11与第三芯层13的相对折射率差最小值Δ％min为0.15％，且第一芯层11的分布幂指数α为-1.85，第三芯层13与第四芯层14的相对折射率差Δ％为0.04％。另外，第一芯层11的半径D1为2.3μm，第二芯层12的半径D2为3.3μm，第三芯层13的半径D3为4.0μm，第四芯层14的半径D4为5.1μm。与此对应的多芯少模光纤的包层3的直径为125μm，涂覆层4的直径为245μm。其中，本实施例对应的多芯少模光纤的主要性能和对应的性能参数如表2所示：
表2 实施例2的多芯少模光纤的主要性能和对应的性能参数
Figure PCTCN2019096641-appb-000004
Figure PCTCN2019096641-appb-000005
实施例3
本实施例中提供的传感用多芯结构少模光纤的制造方法具体为：
在沉积第四芯层14的过程中，控制SiCl 4的流量比例为60％，GeCl 4的流量比例为20％，BCl 3的流量比例为10％，C 2F 6的流量比例为1％，O 2的流量比例为60％，沉积趟数为4000趟；在沉积第三芯层13的过程中，控制SiCl 4的流量比例为50％，GeCl 4的流量比例为15％，C 2F 6的流量比例为10％，O 2的流量比例为65％，沉积趟数1100趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为35％，GeCl 4的流量比例为65％，C 2F 6的流量比例为2％，O 2的流量比例为50％，沉积趟数900趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为60％，GeCl 4的流量比例为20％，BCl 3的流量比例为10％，C 2F 6的流量比例为2％，O 2的流量比例为45％，沉积趟数为5700趟。
与此方法对应的多芯少模光纤的结构参数如下，第一纤芯1距纤体中心的距离均为40μm，第二纤芯2距纤体中心的距离均为40μm，第一纤芯1和第二纤芯2及每两根第二纤芯2之间的距离均为69.2μm。其中，第一芯层11与第三芯层13的相对折射率差最大值Δ％max为1.56％，第一芯层11与第三芯层13的相对折射率差最小值Δ％min 为0.30％，且第一芯层11的分布幂指数α为-1.92，第三芯层13与第四芯层14的相对折射率差Δ％为0.10％。另外，第一芯层11的半径D 1为9.5μm，第二芯层12的半径D 2为10.2μm，第三芯层13的半径D 3为11.7μm，第四芯层14的半径D 4为13.7μm。与此对应的多芯少模光纤的包层3的直径为250μm，涂覆层4的直径为400μm。其中，本实施例对应的多芯少模光纤的主要性能和对应的性能参数如表3所示：
表3 实施例3的多芯少模光纤的主要性能和对应的性能参数
Figure PCTCN2019096641-appb-000006
实施例4
本实施例中提供的传感用多芯结构少模光纤的制造方法具体为：
在沉积第四芯层14的过程中，控制SiCl 4的流量比例为85％，GeCl 4的流量比例为12％，BCl 3的流量比例为25％，C 2F 6的流量比例为7％，O 2的流量比例为60％，沉积趟数为4700趟；在沉积第三芯 层13的过程中，控制SiCl 4的流量比例为60％，GeCl 4的流量比例为10％，C 2F 6的流量比例为37％，O 2的流量比例为50％，沉积趟数1150趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为65％，GeCl 4的流量比例为25％，C 2F 6的流量比例为20％，O 2的流量比例为65％，沉积趟数1100趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为80％，GeCl 4的流量比例为12％，BCl 3的流量比例为25％，C 2F 6的流量比例为10％，O 2的流量比例为65％，沉积趟数为5500趟。
与此方法对应的多芯少模光纤的结构参数如下，第一纤芯1距纤体中心的距离均为45μm，第二纤芯2距纤体中心的距离均为45μm，第一纤芯1和第二纤芯2及每两根第二纤芯2之间的距离均为77.94μm。其中，第一芯层11与第三芯层13的相对折射率差最大值Δ％max为0.32％，第一芯层11与第三芯层13的相对折射率差最小值Δ％min为0.13％，且第一芯层11的分布幂指数α为-1.91，第三芯层13与第四芯层14的相对折射率差Δ％为0.03％。另外，第一芯层11的半径D 1为9.4μm，第二芯层12的半径D 2为11.1μm，第三芯层13的半径D 3为14.1μm，第四芯层14的半径D 4为28.2μm。与此对应的多芯少模光纤的包层3的直径为250μm，涂覆层4的直径为400μm。其中，本实施例对应的多芯少模光纤的主要性能和对应的性能参数如表4所示：
表4 实施例4的多芯少模光纤的主要性能和对应的性能参数
Figure PCTCN2019096641-appb-000007
Figure PCTCN2019096641-appb-000008
实施例5
本实施例中提供的传感用多芯结构少模光纤的制造方法具体为：
在沉积第四芯层14的过程中，控制SiCl 4的流量比例为55％，GeCl 4的流量比例为20％，BCl 3的流量比例为10％，C 2F 6的流量比例为2％，O 2的流量比例为50％，沉积趟数为800趟；在沉积第三芯层13的过程中，控制SiCl 4的流量比例为65％，GeCl 4的流量比例为10％，C 2F 6的流量比例为15％，O 2的流量比例为55％，沉积趟数300趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为60％，GeCl 4的流量比例为25％，C 2F 6的流量比例为22％，O 2的流量比例为70％，沉积趟数900趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为80％，GeCl 4的流量比例为15％，BCl 3的流量比例为20％，C 2F 6的流量比例为10％，O 2的流量比例为55％，沉积趟数为1500趟。
与此方法对应的多芯少模光纤的结构参数如下，第一纤芯1距纤体中心的距离均为32μm，第二纤芯2距纤体中心的距离均为32μm，第一纤芯1和第二纤芯2及每两根第二纤芯2之间的距离均为45.3μm。其中，第一芯层11与第三芯层13的相对折射率差最大值Δ％max为0.35％，第一芯层11与第三芯层13的相对折射率差最小值Δ％min为0.32％，且第一芯层11的分布幂指数α为-1.92，第三芯层13与第 四芯层14的相对折射率差Δ％为0.11％。另外，第一芯层11的半径D 1为4.9μm，第二芯层12的半径D 2为6.2μm，第三芯层13的半径D 3为6.6μm，第四芯层14的半径D 4为7.5μm。与此对应的多芯少模光纤的包层3的直径为125μm，涂覆层4的直径为245μm。其中，本实施例对应的多芯少模光纤的主要性能和对应的性能参数如表5所示：
表5 实施例5的多芯少模光纤的主要性能和对应的性能参数
Figure PCTCN2019096641-appb-000009
实施例6
本实施例中提供的传感用多芯结构少模光纤的制造方法具体为：
在沉积第四芯层14的过程中，控制SiCl 4的流量比例为80％，GeCl 4的流量比例为12％，BCl 3的流量比例为25％，C 2F 6的流量比例为10％，O 2的流量比例为70％，沉积趟数为4200趟；在沉积第三芯 层13的过程中，控制SiCl 4的流量比例为35％，GeCl 4的流量比例为20％，C 2F 6的流量比例为35％，O 2的流量比例为65％，沉积趟数600趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为35％，GeCl 4的流量比例为55％，C 2F 6的流量比例为2％，O 2的流量比例为50％，沉积趟数850趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为75％，GeCl 4的流量比例为15％，BCl 3的流量比例为20％，C 2F 6的流量比例为5％，O 2的流量比例为55％，沉积趟数为4500趟。
与此方法对应的多芯少模光纤的结构参数如下，第一纤芯1距纤体中心的距离均为60μm，第二纤芯2距纤体中心的距离均为60μm，第一纤芯1和第二纤芯2及每两根第二纤芯2之间的距离均为103.92μm。其中，第一芯层11与第三芯层13的相对折射率差最大值Δ％max为1.32％，第一芯层11与第三芯层13的相对折射率差最小值Δ％min为0.14％，且第一芯层11的分布幂指数α为-1.92，第三芯层13与第四芯层14的相对折射率差Δ％为0.04％。另外，第一芯层11的半径D 1为8.5μm，第二芯层12的半径D 2为9.2μm，第三芯层13的半径D 3为9.7μm，第四芯层14的半径D 4为12.7μm。与此对应的多芯少模光纤的包层3的直径为250μm，涂覆层4的直径为350μm。其中，本实施例对应的多芯少模光纤的主要性能和对应的性能参数如表6所示：
表6 实施例6的多芯少模光纤的主要性能和对应的性能参数
Figure PCTCN2019096641-appb-000010
Figure PCTCN2019096641-appb-000011
实施例7
本实施例中提供的传感用多芯结构少模光纤的制造方法具体为：
在沉积第四芯层14的过程中，控制SiCl 4的流量比例为50％，GeCl 4的流量比例为10％，BCl 3的流量比例为30％，C 2F 6的流量比例为7％，O 2的流量比例为70％，沉积趟数为620趟；在沉积第三芯层13的过程中，控制SiCl 4的流量比例为55％，GeCl 4的流量比例为5％，C 2F 6的流量比例为25％，O 2的流量比例为60％，沉积趟数300趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为35％，GeCl 4的流量比例为75％，C 2F 6的流量比例为2％，O 2的流量比例为50％，沉积趟数350趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为55％，GeCl 4的流量比例为15％，BCl 3的流量比例为10％，C 2F 6的流量比例为4％，O 2的流量比例为50％，沉积趟数为270趟。
与此对应的多芯少模光纤的结构参数如下，第一纤芯1距纤体中心的距离均为20μm，第二纤芯2距纤体中心的距离均为20μm，第一纤芯1和第二纤芯2及每两根第二纤芯2之间的距离均为34.64μm。其中，第一芯层11与第三芯层13的相对折射率差最大值Δ％max为2.5％，第一芯层11与第三芯层13的相对折射率差最小值Δ％min为0.18％，且第一芯层11的分布幂指数α为-1.91，第三芯层13与第四 芯层14的相对折射率差Δ％为0.05％。另外，第一芯层11的半径D 1为2.1μm，第二芯层12的半径D 2为3.1μm，第三芯层13的半径D 3为3.8μm，第四芯层14的半径D 4为5.0μm。与此对应的多芯少模光纤的包层3的直径为80μm，涂覆层4的直径为165μm。其中，本实施例对应的多芯少模光纤的主要性能和对应的性能参数如表7所示：
表7 实施例7的多芯少模光纤的主要性能和对应的性能参数
Figure PCTCN2019096641-appb-000012
实施例8
本实施例中提供的传感用多芯结构少模光纤的制造方法具体为：
在沉积第四芯层14的过程中，控制SiCl 4的流量比例为75％，GeCl 4的流量比例为18％，BCl 3的流量比例为10％，C 2F 6的流量比例为1％，O 2的流量比例为55％，沉积趟数为4800趟；在沉积第三芯层13的过程中，控制SiCl 4的流量比例为65％，GeCl 4的流量比例为8％，C 2F 6的流量比例为10％，O 2的流量比例为50％，沉积趟数1200 趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为65％，GeCl 4的流量比例为50％，C 2F 6的流量比例为25％，O 2的流量比例为65％，沉积趟数1100趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为85％，GeCl 4的流量比例为12％，BCl 3的流量比例为30％，C 2F 6的流量比例为10％，O 2的流量比例为70％，沉积趟数为5900趟。
与此方法对应的多芯少模光纤的结构参数如下，第一纤芯1距纤体中心的距离均为175μm，第二纤芯2(第3、第4)距纤体中心的距离均为175μm，第一纤芯1和第二纤芯2及每两根第二纤芯2之间的距离均为247.49μm。其中，第一芯层11与第三芯层13的相对折射率差最大值Δ％max为0.65％，第一芯层11与第三芯层13的相对折射率差最小值Δ％min为0.22％，且第一芯层11的分布幂指数α为-1.89，第三芯层13与第四芯层14的相对折射率差Δ％为0.06％。另外，第一芯层11的半径D 1为9.69μm，第二芯层12的半径D 2为10.56μm，第三芯层13的半径D 3为11.42μm，第四芯层14的半径D 4为14.38μm。与此对应的多芯少模光纤的包层3的直径为850μm，涂覆层4的直径为1000μm。其中，本实施例对应的多芯少模光纤的主要性能和对应的性能参数如表8所示：
表8 实施例8的多芯少模光纤的主要性能和对应的性能参数
Figure PCTCN2019096641-appb-000013
Figure PCTCN2019096641-appb-000014
实施例9
本实施例中提供的传感用多芯结构少模光纤的制造方法具体为：
在沉积第四芯层14的过程中，控制SiCl 4的流量比例为72％，GeCl 4的流量比例为15％，BCl 3的流量比例为18％，C 2F 6的流量比例为5％，O 2的流量比例为70％，沉积趟数为2000趟；在沉积第三芯层13的过程中，控制SiCl 4的流量比例为65％，GeCl 4的流量比例为16％，C 2F 6的流量比例为22％，O 2的流量比例为40％，沉积趟数800趟；在沉积第二芯层12的过程中，控制SiCl 4的流量比例为60％，GeCl 4的流量比例为70％，C 2F 6的流量比例为20％，O 2的流量比例为60％，沉积趟数900趟；在沉积第一芯层11的过程中，控制SiCl 4的流量比例为80％，GeCl 4的流量比例为15％，BCl 3的流量比例为20％，C 2F 6的流量比例为10％，O 2的流量比例为50％，沉积趟数为3500趟。
与此方法对应的多芯少模光纤的结构参数如下，第一纤芯1距纤体中心的距离为62μm，第二纤芯距纤体中心的距离均为62μm，第一纤芯1和第三纤芯2及每两根第二纤芯2之间的距离均为100.32μm。其中，第一芯层11与第三芯层13的相对折射率差最大值Δ％max为0.98％，第一芯层11与第三芯层13的相对折射率差最小值Δ％min为0.19％，且第一芯层11的分布幂指数α为-1.90，第三芯层13与第四芯层14的相对折射率差Δ％为0.05％。另外，第一芯层11的半径 D 1为7.4μm，第二芯层12的半径D 2为8.3μm，第三芯层13的半径D 3为9.1μm，第四芯层14的半径D 4为10.7μm。与此对应的多芯少模光纤的包层3的直径为250μm，涂覆层4的直径为350μm。其中，本实施例对应的多芯少模光纤的主要性能和对应的性能参数如表9所示：
表9 实施例9的多芯少模光纤的主要性能和对应的性能参数
Figure PCTCN2019096641-appb-000015
本发明不仅局限于上述最佳实施方式，任何人在本发明启示下都可得出其他各种形式的产品，但不论在其形状或结构上作任何变化，凡是具有与本发明相同或相近似的技术方案，均在其保护范围之内。

Claims (14)

  1. 一种多芯少模光纤，其特征在于，其包括：
    纤体，其包括有距所述纤体中心预定距离且相互间隔设置的至少一根第一纤芯(1)和至少两根第二纤芯(2)，所述第一纤芯(1)和第二纤芯(2)均包括至少一循环层，所述循环层包括三层芯层，且所述循环层的外侧还设有一层芯层，所述第一纤芯(1)和第二纤芯(2)任意相邻两层芯层的折射率或直径不同，其中，所述第一纤芯(1)的有效折射率和直径中的至少一种与所述第二纤芯(2)不同；
    包层(3)，其包围所述第一纤芯(1)和第二纤芯(2)，所述包层(3)的折射率低于所述第一纤芯(1)和第二纤芯(2)的有效折射率，高于所述第一纤芯(1)和第二纤芯(2)最外侧芯层的折射率。
  2. 如权利要求1所述的一种多芯少模光纤，其特征在于：所述循环层包括从内至外依次设置的第一芯层(11)、第二芯层(12)和第三芯层(13)，位于所述循环层外侧的芯层为第四芯层(14)，其中，所述第一芯层(11)与第三芯层(13)的最大相对折射率差为0.3％～2.5％，最小相对折射率差为0.05％～0.6％，所述第三芯层(13)与第四芯层(14)的相对折射率差为0％～1.1％。
  3. 如权利要求2所述的一种多芯少模光纤，其特征在于：所述第三芯层(13)的折射率大于或等于所述包层(3)的折射率，所述第四芯层(14)、包层(3)和第三芯层(13)的折射率为近似阶跃分布。
  4. 如权利要求2所述的一种多芯少模光纤，其特征在于：所述第一芯层(11)的折射率的分布幂指数α为-1.2～-2.5。
  5. 如权利要求2所述的一种多芯少模光纤，其特征在于：所述第一纤芯(1)和第二纤芯(2)均包括多个依次设置的循环层，所述 第四芯层(14)设于最外侧的所述循环层外。
  6. 如权利要求1所述的一种多芯少模光纤，其特征在于：所述预定距离为32～248μm。
  7. 如权利要求1所述的一种多芯少模光纤，其特征在于：所述第一纤芯(1)的根数最多为3根。
  8. 如权利要求1所述的一种多芯少模光纤，其特征在于：所述纤体还包括涂覆层(4)，所述涂覆层(4)设于所述包层(3)的外侧。
  9. 如权利要求8所述的一种多芯少模光纤，其特征在于：所述涂覆层(4)的厚度为20～100μm，所述包层(3)的半径为30～500μm。
  10. 如权利要求9所述的一种多芯少模光纤，其特征在于：所述涂覆层(4)为双层丙烯酸树脂、聚酰亚胺、单层丙烯酸树或硅橡胶中的一种。
  11. 如权利要求1所述的一种多芯少模光纤的制造方法，其特征在于，该方法包括以下步骤：
    在石英反应管内采用包括四氯化硅SiCl 4、四氯化锗GeCl 4、三氯氧磷BCl 3、六氟乙烷C 2F 6和氧气O 2的沉积原料从外至内分别沉积四层芯层，在沉积过程中，通过分别调整所述沉积原料的流量比例以及沉积的趟数来调节各层所述芯层之间的相对折射率差和半径比；
    将沉积后的所述石英反应管在2000℃以上的温度下熔缩成实心芯棒；
    设定不同的沉积原料的流量比例以及沉积的趟数来制备多根与第一纤芯(1)和第二纤芯(2)对应的实心芯棒；
    将石英管制成实心棒，在所述实心棒的不同预定位置钻孔，并将多根所述实心芯棒磨制加工后放入至所述实心棒的孔洞中并进行熔缩，形成与所述第一纤芯(1)或第二纤芯(2)对应的多芯结构少模 光纤预制棒；
    对所述多芯结构少模光纤预制棒进行拉丝，制成多芯结构少模光纤。
  12. 如权利要求11所述的制造方法，其特征在于：所述四层芯层包括从内至外设置的第一芯层(11)、第二芯层(12)、第三芯层(13)和第四芯层(14)，其中，
    在沉积所述第四芯层(14)的过程中，控制SiCl 4的流量比例为50～85％，GeCl 4的流量比例为10～20％，BCl 3的流量比例为10～30％，C 2F 6的流量比例为0～10％，O 2的流量比例为30～70％，沉积趟数为600～4800趟；
    在沉积所述第三芯层(13)的过程中，控制SiCl 4的流量比例为30～70％，GeCl 4的流量比例为0～20％，C 2F 6的流量比例为10～40％，O 2的流量比例为30～70％，沉积趟数200～1200趟；
    在沉积所述第二芯层(12)的过程中，控制SiCl 4的流量比例为30～70％，GeCl 4的流量比例为20～75％，C 2F 6的流量比例为0～25％，O 2的流量比例为30～70％，沉积趟数300～1200趟；
    在沉积所述第一芯层(11)的过程中，控制SiCl 4的流量比例为50～85％，GeCl 4的流量比例为10～20％，BCl 3的流量比例为10～30％，C 2F 6的流量比例为0～10％，O 2的流量比例为30～70％，沉积趟数为200～6000趟。
  13. 如权利要求11所述的制造方法，其特征在于：所述预定位置分别与距所述纤体中心预定距离的所述第一纤芯(1)和第二纤芯(2)的位置对应。
  14. 如权利要求11所述的制造方法，其特征在于：采用等离子体化学气相沉积法来沉积所述芯层。
PCT/CN2019/096641 2019-06-04 2019-07-19 一种多芯少模光纤及其制造方法 Ceased WO2020244034A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19931680.3A EP3982175B1 (en) 2019-06-04 2019-07-19 Multi-core few-mode optical fiber and manufacturing method therefor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN201910482739.3 2019-06-04
CN201910482739.3A CN110346864B (zh) 2019-06-04 2019-06-04 一种多芯少模光纤及其制造方法

Publications (1)

Publication Number Publication Date
WO2020244034A1 true WO2020244034A1 (zh) 2020-12-10

Family

ID=68181522

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2019/096641 Ceased WO2020244034A1 (zh) 2019-06-04 2019-07-19 一种多芯少模光纤及其制造方法

Country Status (3)

Country Link
EP (1) EP3982175B1 (zh)
CN (1) CN110346864B (zh)
WO (1) WO2020244034A1 (zh)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113156574A (zh) * 2021-04-16 2021-07-23 华中科技大学 一种多参数优化的轨道角动量掺铒光纤
US20230204851A1 (en) * 2021-12-28 2023-06-29 Sterlite Technologies Limited Multi-core optical fiber

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111635125A (zh) * 2020-04-21 2020-09-08 艾菲博(宁波)光电科技有限责任公司 一种高占空比的多芯微结构成像光纤束的制备方法
CN114063208A (zh) * 2020-07-30 2022-02-18 华为技术有限公司 一种光纤及光缆
CN111897046A (zh) * 2020-09-18 2020-11-06 长飞光纤光缆股份有限公司 一种便于识别和对接的多芯光纤
CN112198586B (zh) * 2020-09-25 2021-11-19 北京邮电大学 一种多芯光纤
CN112198587B (zh) * 2020-09-28 2021-12-31 北京邮电大学 一种多芯少模光纤及其参数的确定方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130039627A1 (en) * 2011-08-12 2013-02-14 University Of Central Florida Research Foundation, Inc. Systems And Methods For Optical Transmission Using Supermodes
CN103630965A (zh) * 2013-12-03 2014-03-12 烽火通信科技股份有限公司 一种抗弯曲拉锥光纤及其制造方法
US9081129B2 (en) * 2012-01-19 2015-07-14 Fujikura Ltd. Multi-core fiber
CN105425335A (zh) * 2015-12-17 2016-03-23 长飞光纤光缆股份有限公司 一种通信用抗弯多芯光纤
CN106461859A (zh) * 2015-03-30 2017-02-22 株式会社藤仓 多芯光纤以及多芯光纤的制造方法
CN108292009A (zh) * 2015-11-19 2018-07-17 康宁股份有限公司 采用多纤芯光纤的分布式光纤传感器和系统
CN208367258U (zh) * 2018-03-19 2019-01-11 江苏斯德雷特通光光纤有限公司 一种低串扰大模场面积多芯光纤

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1584641A (zh) * 2004-06-01 2005-02-23 中国科学院上海光学精密机械研究所 光子晶体光纤
CN101738681B (zh) * 2010-01-20 2011-08-31 长飞光纤光缆有限公司 一种高带宽多模光纤
JP5267481B2 (ja) * 2010-02-18 2013-08-21 住友電気工業株式会社 マルチコア光ファイバ
CN103403591A (zh) * 2011-03-04 2013-11-20 株式会社藤仓 多芯光纤、以及使用了多芯光纤的多芯光纤的连接方法
IL231049B (en) * 2013-02-19 2021-04-29 Teldor Cables & Systems Ltd Two-color coating of optical fibers with ultraviolet reactive ink
JP5835823B1 (ja) * 2014-07-09 2015-12-24 日本電信電話株式会社 マルチコア光ファイバ母材の製造方法
JP6550061B2 (ja) * 2014-09-05 2019-07-24 古河電気工業株式会社 マルチコアファイバおよびその製造方法
JP6334582B2 (ja) * 2016-01-29 2018-05-30 株式会社フジクラ マルチコアファイバ
JP6722271B2 (ja) * 2016-03-17 2020-07-15 株式会社フジクラ マルチコアファイバ

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130039627A1 (en) * 2011-08-12 2013-02-14 University Of Central Florida Research Foundation, Inc. Systems And Methods For Optical Transmission Using Supermodes
US9081129B2 (en) * 2012-01-19 2015-07-14 Fujikura Ltd. Multi-core fiber
CN103630965A (zh) * 2013-12-03 2014-03-12 烽火通信科技股份有限公司 一种抗弯曲拉锥光纤及其制造方法
CN106461859A (zh) * 2015-03-30 2017-02-22 株式会社藤仓 多芯光纤以及多芯光纤的制造方法
CN108292009A (zh) * 2015-11-19 2018-07-17 康宁股份有限公司 采用多纤芯光纤的分布式光纤传感器和系统
CN105425335A (zh) * 2015-12-17 2016-03-23 长飞光纤光缆股份有限公司 一种通信用抗弯多芯光纤
CN208367258U (zh) * 2018-03-19 2019-01-11 江苏斯德雷特通光光纤有限公司 一种低串扰大模场面积多芯光纤

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP3982175A4 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113156574A (zh) * 2021-04-16 2021-07-23 华中科技大学 一种多参数优化的轨道角动量掺铒光纤
CN113156574B (zh) * 2021-04-16 2023-06-16 华中科技大学 一种多参数优化的轨道角动量掺铒光纤
US20230204851A1 (en) * 2021-12-28 2023-06-29 Sterlite Technologies Limited Multi-core optical fiber

Also Published As

Publication number Publication date
EP3982175A1 (en) 2022-04-13
EP3982175C0 (en) 2025-09-24
CN110346864B (zh) 2020-10-27
EP3982175B1 (en) 2025-09-24
CN110346864A (zh) 2019-10-18
EP3982175A4 (en) 2023-06-28

Similar Documents

Publication Publication Date Title
CN110346864B (zh) 一种多芯少模光纤及其制造方法
RU2489741C2 (ru) Многосердцевинный волоконный световод (варианты)
CN101825738B (zh) 一种熊猫型保偏光纤
US9897751B2 (en) Multicore polarization-maintaining fiber
CN103698843B (zh) 一种低简并度少模光纤
EP3761087A1 (en) Multicore fiber and manufacturing method therefor, and optical transmission system and optical transmission method
CN103472530B (zh) 一种大芯径弯曲不敏感传能光纤
CN105403952A (zh) 一种低损耗抗辐照的双折射光子晶体光纤
CN112099130B (zh) 一种低芯间串扰的斜坡型折射率分布多芯光纤
CN106772786B (zh) 一种支持多个线偏振模式与轨道角动量模式的少模光纤
US11550097B2 (en) Array-type polarization-maintaining multi-core fiber
CN113433610A (zh) 一种空芯保偏光纤
CN107346046A (zh) 具有侧面识别标记的非圆对称光纤
CN111427117B (zh) 弱耦合十模式少模光纤及其实现方法
CN102375176B (zh) 一种低弯曲损耗光纤
CN105891947A (zh) 一种多空气包层的抗弯曲光纤及其制造方法
CN103630965A (zh) 一种抗弯曲拉锥光纤及其制造方法
WO2018138736A2 (en) Optical fiber draw assembly and fabricated optical fiber thereof
CN103901533A (zh) 一种纯硅纤芯低损耗弯曲不敏感单模光纤
CN106199821A (zh) 一种基于13芯结构的保偏光子带隙光纤
CN103207430B (zh) 一种低弯曲损耗微结构光纤
CN102023334A (zh) 一种大模场光纤
CN107490820A (zh) 一种全固态大模面积近零色散平坦微结构光纤
CN103257396B (zh) 一种色散平坦光子晶体光纤及其色散调控方法
JP2014228705A (ja) マルチコア光ファイバ及びその製造方法

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19931680

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2019931680

Country of ref document: EP

Effective date: 20220104

WWG Wipo information: grant in national office

Ref document number: 2019931680

Country of ref document: EP