WO2025123624A1 - 低损耗单模光纤 - Google Patents

低损耗单模光纤 Download PDF

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Publication number
WO2025123624A1
WO2025123624A1 PCT/CN2024/099275 CN2024099275W WO2025123624A1 WO 2025123624 A1 WO2025123624 A1 WO 2025123624A1 CN 2024099275 W CN2024099275 W CN 2024099275W WO 2025123624 A1 WO2025123624 A1 WO 2025123624A1
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Prior art keywords
optical fiber
layer
core layer
low
mode optical
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PCT/CN2024/099275
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English (en)
French (fr)
Inventor
王见青
沈一春
秦钰
蒋新力
陈娅丽
徐希凯
周慧
张俊逸
张泽霖
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Zhongtian Technology Advanced Materials Co Ltd
Zhongtian Technology Fiber Optics Co Ltd
Zhongtian Technology Group Co Ltd
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Zhongtian Technology Advanced Materials Co Ltd
Zhongtian Technology Fiber Optics Co Ltd
Zhongtian Technology Group Co Ltd
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Priority to EP24875713.0A priority Critical patent/EP4597180A4/en
Publication of WO2025123624A1 publication Critical patent/WO2025123624A1/zh
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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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
    • G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
    • G02B6/0281—Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core
    • 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
    • G02B6/03688—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 5 or more layers
    • 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
    • G02B6/03672—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 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
    • G02B6/03694—Multiple layers differing in properties other than the refractive index, e.g. attenuation, diffusion, stress properties
    • 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 - - +

Definitions

  • Optical fiber is the transmission medium of optical fiber communication networks.
  • a longer non-relay transmission distance can be obtained, which can effectively reduce the cost of network and system construction.
  • the main component of optical fiber is SiO 2.
  • GeO 2 is added to increase the refractive index of the core layer, which is the main source of reducing optical fiber attenuation.
  • F element can also be added to the cladding to reduce the refractive index of the cladding, ensure the refractive index difference between the core layer and the cladding, and further reduce the optical fiber attenuation.
  • the viscosity/thermal expansion coefficient between the core layer and the cladding is inverted, the viscosity/thermal expansion coefficient matching of the optical fiber structure is unbalanced, and a large stress is generated at the interface between the core layer and the cladding, which will lead to increased optical fiber attenuation.
  • an embodiment of the present application provides a low-loss single-mode optical fiber to solve the technical problem of high optical fiber attenuation of single-mode optical fibers in related technologies.
  • the embodiment of the present application provides a low-loss single-mode optical fiber, which includes a core layer and a cladding layer surrounding the core layer, wherein the core layer includes an inner core layer and an outer core layer, wherein the inner core layer is doped with P and GeO 2 , and the outer core layer is doped with F, P and GeO 2 .
  • the inner core layer is doped with GeO2 at a molar concentration of 0.10-1.5% and P element at a molar concentration of 0.01-0.3%;
  • the outer core layer is doped with GeO2 at a molar concentration of 0.10-1.5%, P element at a molar concentration of 0.01-0.3% and F element at a molar concentration of 0-1.5%.
  • the refractive index of the core layer is distributed in a parabolic gradient.
  • the cladding includes an inner cladding, a first depressed layer, a doping layer, a second depressed layer and an outer cladding which are stacked in sequence from the center to the periphery;
  • the inner cladding is doped with GeO2 with a molar concentration of 0-0.2%, a P element with a molar concentration of 0.01-0.3% and an F element with a molar concentration of 0.5-1.5%;
  • the first depressed layer is doped with GeO2 with a molar concentration of 0-0.2% and an F element with a molar concentration of 0-2.0%;
  • the doping layer is doped with GeO2 with a molar concentration of 0-0.2% and an F element with a molar concentration of 0-2.0%;
  • the second depressed layer is doped with GeO2 with a molar concentration of 0-0.2% and an F element with a molar concentration of 0-3.0%.
  • the relative refractive index difference ⁇ 1 between the inner core layer and the outer cladding is 0.10-0.25%; the relative refractive index difference ⁇ 2 between the outer core layer and the outer cladding is 0-0.20%; the relative refractive index difference ⁇ 3 between the inner cladding and the outer cladding is -0.10 to -0.30%; the relative refractive index difference ⁇ 4 between the first depressed layer and the outer cladding is -0.25 to -0.50%; the relative refractive index difference ⁇ 5 between the doping layer and the outer cladding is -0.30 to -0%; the relative refractive index difference ⁇ 6 between the second depressed layer and the outer cladding is -0.50-0%.
  • the radius R1 of the inner core layer is 2-6 ⁇ m; the radius of the outer core layer is R2, and the range of R2-R1 is 3.0-5.0 ⁇ m; the radius of the inner cladding is R3, and the range of R3-R2 is 2-5 ⁇ m; the radius of the first depressed layer is R4, and the range of R4-R3 is 2-8 ⁇ m; the radius of the doping layer is R5, and the range of R5-R4 is 5-30 ⁇ m; the radius of the second depressed layer is R6, and the range of R6-R5 is 10-22 ⁇ m; the radius R7 of the outer cladding is 60-65 ⁇ m.
  • the application wavelength range of the low-loss single-mode optical fiber is 1310-1550 nm.
  • the mode field diameter of the low-loss single-mode optical fiber at an application wavelength of 1310 nm is 8.7-9.7 ⁇ m; the mode field diameter of the low-loss single-mode optical fiber at an application wavelength of 1550 nm is 9.5-10.5 ⁇ m.
  • the attenuation coefficient of the low-loss single-mode optical fiber at an application wavelength of 1310 nm is ⁇ 0.350 dB/km; the attenuation coefficient of the low-loss single-mode optical fiber at an application wavelength of 1550 nm is ⁇ 0.175 dB/km.
  • the zero dispersion wavelength range of the low-loss single-mode optical fiber is 1300-1324 nm, and the dispersion slope of the low-loss single-mode optical fiber at the zero dispersion wavelength is ⁇ 0.092 ps/(nm 2 *km); the dispersion coefficient of the low-loss single-mode optical fiber at the application wavelength of 1550 nm is ⁇ 18 ps/(nm*km).
  • the embodiment of the present application provides a low-loss single-mode optical fiber, which includes a core layer and a cladding layer surrounding the core layer, wherein the core layer includes an inner core layer and an outer core layer, wherein the inner core layer is doped with P and GeO 2 , and the outer core layer is doped with F, P, and GeO 2 .
  • the core layer includes an inner core layer and an outer core layer, wherein the inner core layer is doped with P and GeO 2 , and the outer core layer is doped with F, P, and GeO 2 .
  • FIG1 is a schematic cross-sectional view of a low-loss single-mode optical fiber provided in an embodiment of the present application
  • FIG2 is a schematic diagram of the cross-sectional structure of a low-loss single-mode optical fiber provided in an embodiment of the present application
  • FIG3 is a schematic diagram of the refractive index distribution of a low-loss single-mode optical fiber according to Example 1 provided in an embodiment of the present application;
  • FIG4 is a schematic diagram showing a comparison of stress distribution of a low-loss single-mode optical fiber according to Example 1 provided in an embodiment of the present application;
  • FIG6 is a schematic diagram of the refractive index distribution of a low-loss single-mode optical fiber according to Example 5 provided in an embodiment of the present application;
  • the existing low-loss cutoff wavelength shifted single-mode optical fiber is directly matched with the pure silicon sleeve drawing, and the position of the cutoff wavelength migration is inconvenient to adjust, resulting in a narrow applicable wavelength range of the preform drawn optical fiber.
  • the refractive index of the core layer presents a parabolic gradient distribution, which can achieve a gradual change in physical properties and doping concentration, eliminate or reduce the interface stress difference between the core and cladding layers, and reduce the 1550 dispersion value to meet the requirements of the G652 standard while keeping the mode field diameter unchanged.
  • the position of the cutoff wavelength migration is controlled by adjusting the refractive index of the F-doped interlayer tube used for matching drawing, so that the drawn optical fiber can be adjusted to different wavelength ranges.
  • the optical fiber has lower attenuation loss and better anti-bending properties.
  • the cut-off wavelength of the low-loss single-mode optical fiber in the embodiment of the present application can be adjusted according to the application band to obtain the optimal bending performance, provided that other main properties (MFD, dispersion performance) match G652.
  • the inner core layer 100 and the outer core layer 200 of the low-loss single-mode optical fiber replace the effect of F element doping on viscosity regulation by trace doping of P element, while keeping the refractive index of the core layer unchanged, effectively reducing the GE doping amount of the core layer and reducing Rayleigh scattering.
  • the low-loss single-mode optical fiber provided in the embodiment of the present application has a core layer with a parabolic gradient design, which can achieve a gradual change in physical properties and doping concentration, eliminate or reduce the interface stress difference between the core and cladding, and reduce the 1550 dispersion value while keeping the mode field diameter unchanged to meet the G652 standard requirements.
  • the outer cladding 700 is made of pure silicon dioxide without being doped with other elements.
  • the outer core layer 200 is a silica glass layer doped with GeO 2 , P element and F element.
  • the low-loss single-mode optical fiber is suitable for various manufacturing processes or hybrid processes such as MCVD and PCVD.
  • the optical cable cutoff wavelength migration position of the low-loss single-mode optical fiber is adjustable ( ⁇ 1530nm).
  • the macro-bending loss of 15mm radius-10 turns is ⁇ 0.03dB; the macro-bending loss of 10mm radius-1 turn is ⁇ 0.1dB, and the macro-bending loss of 7.5mm radius-1 turn is ⁇ 0.5dB.
  • the low-loss single-mode optical fiber of the present application is described in detail below through Examples 1 to 6.
  • the prefabricated core rod is prepared by using an improved in-tube chemical vapor deposition method MCVD or a plasma chemical vapor deposition method PCVD process, wherein the doping layer 500 can be composed of a quartz substrate tube doped with F elements, the quartz tube doped with F elements is used as the deposition substrate tube, SiCl 4 and O 2 are raw materials for SiO 2 , SiF 4 , SF 6 , C 2 F 6 or CF 4 are raw materials for doping with F elements, GECl 4 is used as a raw material for doping with GE elements, and POCl 3 is a raw material for doping with P elements.
  • MCVD a plasma chemical vapor deposition method PCVD process
  • the inner surface of the F-doped base tube is deposited in sequence to obtain a recessed layer, an inner cladding layer, an outer core layer and an inner core layer; then the deposited tube is melted and shrunk to a suitable inner diameter at a high temperature, and before the inner diameter is shrunk, SF6 or C2F6 and O2 are introduced to etch and remove impurities adhering to the inner diameter surface under the heating of a hydrogen-oxygen torch or a graphite furnace, and finally melted and shrunk at a high temperature to form a solid core rod.
  • An F-doped quartz sleeve is used as the second depressed layer 600 and a pure quartz sleeve is used as the outer cladding 700 for matching and drawing, and the optical fiber is obtained by high-temperature drawing.
  • the optical fiber cross-sectional structure includes an inner core layer 100, an outer core layer 200, an inner cladding layer 300, a first depressed layer 400, a doping layer 500, a second depressed layer 600 and an outer cladding layer 700.
  • the radius of the inner core layer 100 is R1, and the relative refractive index difference is ⁇ 1; the radius of the outer core layer 200 is R2, and the relative refractive index difference is ⁇ 2; the radius of the inner cladding layer 300 is R3, and the relative refractive index difference is ⁇ 3; the radius of the first depressed layer 400 is R4, and the relative refractive index difference is ⁇ 4; the radius of the doping layer 500 is R5, and the relative refractive index difference is ⁇ 5; the radius of the second depressed layer 600 is R6, and the relative refractive index difference is ⁇ 6; the outer cladding layer 700 is pure silica, and its radius R7 is 62.5 ⁇ m, and the relative refractive index difference is 0%.
  • the detection standard of MFD mode field diameter: "GBT-15972.45-2008 Fiber Test Method Specification Part 45: Measurement and Test Methods and Test Procedures for Transmission Characteristics and Optical Characteristics Mode Field Diameter”.
  • Cable cut-off wavelength detection standard "GBT-15972.44-2008 Fiber Test Method Specification Part 44: Transmission Characteristics and Optical Characteristics Measurement Test Methods and Test Procedures Cut-off Wavelength”.
  • Attenuation coefficient test standard "GBT-15972.40-2008 Fiber optic test method specification Part 40: Measurement test methods and test procedures for transmission characteristics and optical characteristics attenuation".
  • Dispersion detection standard "GBT-15972.42-2008 Fiber Test Method Specification Part 42: Measurement Test Methods and Test Procedures for Transmission Characteristics and Optical Characteristics Wavelength Dispersion".
  • the radius R1 of the inner core layer 100 is 2.5 ⁇ m, and ⁇ 1 is 0.14%; the thickness R2-R1 of the outer core layer 200 is 3.8 ⁇ m, and ⁇ 2 is 0%; the thickness R3-R2 of the inner cladding 300 is 2.5 ⁇ m, and ⁇ 3 is -0.22%; the thickness R4-R3 of the first depressed layer 400 is 4.8 ⁇ m, and ⁇ 4 is -0.34%; the thickness R5-R4 of the doping layer 500 is 7.9 ⁇ m, and the relative refractive index difference ⁇ 5 is -0.22%; the thickness R6-R5 of the second depressed layer 600 is 20 ⁇ m, and the relative refractive index difference ⁇ 6 is -0.28%; the outer cladding is pure silica, and the radius R7 is 62.5 ⁇ m.
  • the mode field diameter of the drawn optical fiber at 1310nm is 9.2 ⁇ m
  • the mode field diameter at 1550nm is 10.5 ⁇ m
  • the cable cut-off wavelength is 1240nm
  • the attenuation at 1310nm and 1550nm are 0.288dB/km and 0.163dB/km respectively
  • the zero dispersion wavelength is 1314nm
  • the zero dispersion wavelength slope is 0.087ps/( nm2 *km
  • the dispersion value at 1550nm is 16.6ps/(nm*km)
  • all the performances of the optical fiber meet the G652 standard.
  • the refractive index distribution of the optical fiber obtained in Example 1 was tested using an optical fiber refractive index profile tester (the scanning laser used a standard wavelength of 632 nm), and the refractive index distribution diagram thereof was obtained as shown in FIG. 3 .
  • Example 4 The stress distribution of the optical fiber obtained in Example 1 was tested using an optical fiber stress tester. Under the same profile design, the inner/outer core layers were prepared by only doping F without doping P. The comparison of the stress distribution diagrams of the two optical fibers is shown in Figure 4.
  • F-doped fiber needs to dope more GE in the core layer to ensure the refractive index difference of the core layer, which not only leads to increased Rayleigh scattering, but also more obvious stress mutation between the core layer and the depression layer.
  • P-doping in the core layer is more effective than F-doping in reducing the stress mismatch between the core layer and the depression layer.
  • the refractive index ⁇ 1 is reduced from 0.14% to 0.12%, and other structural parameters are basically the same as Example 1.
  • the zero dispersion wavelength is migrated to 1318nm, the zero dispersion wavelength slope is 0.087ps/( nm2 *km), the dispersion value of 1550nm is 16.4ps/(nm*km), the attenuation of 1550nm is 0.180dB/km, which increases significantly, and the attenuation of 1310nm is 0.285dB/km, which decreases slightly
  • the cable cutoff wavelength is reduced to 1120nm, and the bending losses of R15*10@1550nm, R10*1@1550nm, and R7.5*1@1550nm increase significantly, indicating that the optical signal has leakage at long wavelengths.
  • Example 3 Compared with Example 1, the refractive index parameters corresponding to each structural layer of the optical fiber in Example 3 remain basically unchanged. Since the inner core layer adopts Ge/F/P co-doping, under the condition that the refractive index of the core layer remains unchanged, the Ge doping amount of the core layer increases, and the Rayleigh scattering loss caused by it also increases. The 1310nm attenuation and 1550nm attenuation of the designed optical fiber increase to 0.297dB/km and 0.169dB/km, and other parameters remain basically unchanged.
  • Embodiment 4 is a diagrammatic representation of Embodiment 4:
  • Example 1 Compared with Example 1, while the core layer diameter and height remain unchanged, the core layer is changed to a step design, and the core layer half-height width is increased compared with Example 1. In addition, due to the sudden increase in stress of the core cladding, the bending loss is reduced, but the 1310nm attenuation and 1550nm attenuation are increased to 0.304dB/km and 0.178dB/km, respectively.
  • the cable wavelength is increased to 1340nm, the zero dispersion wavelength is migrated to 1298nm, the zero dispersion wavelength slope is 0.093ps/( nm2 *km), the 1550nm dispersion value is 18.9ps/(nm*km), and the optical fiber dispersion index exceeds the G652 standard.
  • the core step design has greater advantages in attenuation and dispersion control than the core parabolic gradient design. Clearly insufficient.
  • Example 5 does not have the second depressed layer 600 design.
  • the core layer refractive index is increased by 0.19%, the core layer Ge doping amount is increased, @1550nm attenuation is increased to 0.172dB/km, and the cable wavelength has no significant change.
  • the zero dispersion wavelength is migrated to 1308nm, the zero dispersion wavelength slope is 0.090ps/(nm 2 *km), the 1550nm dispersion value is 17.9ps/(nm*km), and the fiber dispersion index is close to the upper limit of the G652 standard.
  • Example 6 does not have the design of the second depressed layer 600.
  • the width and depth of the first depressed layer 400 are increased to 7.4 ⁇ m and -0.42%, respectively.
  • the cable wavelength is increased to 1335 nm, exceeding the upper limit of the G652 standard.
  • the mode field diameter is reduced to 8.8 ⁇ m, close to the lower limit of the standard, and the dispersion parameters have no obvious changes.
  • the low-loss single-mode optical fiber of the embodiment of the present application includes a core layer and a cladding surrounding the core layer, the core layer includes an inner core layer 100 and an outer core layer 200, the cladding includes an inner cladding 300, a first depressed layer 400, a doping layer 500, a second depressed layer 600 and an outer cladding 700 stacked in sequence from the center to the periphery;
  • the inner core layer 100 is doped with P and GeO 2
  • the outer core layer 200 is doped with F, P, and GeO 2
  • the inner cladding 300 is doped with GeO 2 , P element and F element
  • the first depressed layer 400 is doped with GeO 2 and F element
  • the doping layer 500 is doped with GeO 2 and F element
  • the second depressed layer 600 is doped with GeO 2 and F element.
  • the Rayleigh scattering is reduced by adjusting the doping elements in the inner and outer core layers, thereby achieving the purpose of reducing the optical fiber attenuation coefficient.
  • the position of the cutoff wavelength migration is also controlled by adjusting the refractive index of the F-doped interlayer tube for matching drawing, so that the drawn optical fiber can be adjusted to different wavelength ranges.
  • the optical fiber has lower attenuation loss and better anti-bending properties.
  • the low-loss single-mode optical fiber provided in the embodiment of the present application adopts a parabolic gradient design, which can, on the one hand, achieve a gradual change in physical properties and doping concentration, eliminate or reduce the interface stress difference between the core and cladding, and on the other hand, effectively reduce the zero dispersion wavelength slope and 1550 dispersion value of the optical fiber while keeping the mode field diameter unchanged, thereby reducing dispersion compensation when used as a long-distance trunk transmission optical fiber.
  • the low-loss single-mode optical fiber provided in the embodiment of the present application is provided with a
  • the second depressed layer 600 can effectively reduce the refractive index of the core layer and the Rayleigh scattering loss caused by GeO 2 doping while preventing optical power leakage, thereby ensuring low attenuation loss of the optical fiber.
  • spatially relative terms such as “below,” “below,” “beneath,” “above,” “above,” etc., may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. The device may have other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein may likewise be interpreted accordingly.

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Abstract

一种低损耗单模光纤，涉及通信光纤技术领域，该低损耗单模光纤包括芯层和围绕于芯层外围的包层，芯层包括内芯层（100）和外芯层（200），内芯层（100）中掺杂有P、GeO 2，外芯层（200）中掺杂有F、P、GeO 2。通过调整内芯层（100）和外芯层（200）中掺杂的元素减少瑞利散射，从而达到降低光纤衰减系数的目的，使光纤具有更低的衰减损耗和更优的抗弯曲特性。

Description

低损耗单模光纤 技术领域
本申请涉及通信光纤技术领域，尤其涉及一种低损耗单模光纤。
背景技术
光纤是光纤通信网络的传输媒质，光纤衰减越低，整个链路的光功率损耗将越少，在传输过程中能得到更长的无中继传输距离，可以有效降低网络和系统建设的成本。
光纤的主要成分是SiO2，在制造光纤预制棒时，通过掺入GeO2来提高芯层的折射率，是降低光纤衰减的最主要来源；同时，还可以在包层中掺入F元素，以降低包层的折射率，保证芯层与包层之间的折射率差值，进一步降低光纤衰减。
然而，上述技术方案中，在制造光纤预制棒时，芯层与包层之间的粘度/热膨胀系数出现倒置，光纤结构粘度/热膨胀系数匹配失衡，芯层和包层界面产生较大应力，将导致光纤衰减增加。
发明内容
鉴于上述问题，本申请实施方式提供一种低损耗单模光纤，以解决相关技术中的单模光纤的光纤衰减大的技术问题。
为了实现上述目的，本申请实施方式提供如下技术方案：
本申请实施方式提供的一种低损耗单模光纤，其包括芯层和围绕于所述芯层外围的包层，所述芯层包括内芯层和外芯层，所述内芯层中掺杂有P、GeO2,所述外芯层中掺杂有F、P、GeO2。
在一种可能的实现方式中，所述内芯层中掺杂有摩尔浓度为0.10-1.5％的GeO2和摩尔浓度为0.01-0.3％的P元素；所述外芯层中掺杂有摩尔浓度为0.10-1.5％的GeO2、摩尔浓度为0.01-0.3％的P元素和摩尔浓度为0-1.5％的F元素。
在一种可能的实现方式中，所述芯层的折射率呈抛物线渐变型分布。
在一种可能的实现方式中，所述包层包括由中心至外周依次层叠设置的内包层、第一凹陷层、掺杂层、第二凹陷层以及外包层；所述内包层中掺杂有摩尔浓度为0-0.2％的GeO2、摩尔浓度为0.01-0.3％的P元素和摩尔浓度为0.5-1.5％的F元素；所述第一凹陷层中掺杂有摩尔浓度为0-0.2％的GeO2和摩尔浓度为0-2.0％的F元素；所述掺杂层中掺杂有摩尔浓度为0-0.2％的GeO2和摩尔浓度为0-2.0％的F元素；所述第二凹陷层中掺杂有摩尔浓度为0-0.2％的GeO2和摩尔浓度为0-3.0％的F元素。
在一种可能的实现方式中，所述内芯层与所述外包层之间的相对折射率差Δ1为0.10-0.25％；所述外芯层与所述外包层之间的相对折射率差Δ2为0-0.20％；所述内包层与所述外包层之间的相对折射率差Δ3为-0.10至-0.30％；所述第一凹陷层与所述外包层之间的相对折射率差Δ4为-0.25至-0.50％；所述掺杂层与所述外包层之间的相对折射率差Δ5为-0.30至-0％；所述第二凹陷层与所述外包层之间的相对折射率差Δ6为-0.50-0％。
在一种可能的实现方式中，所述内芯层的半径R1为2-6μm；所述外芯层的半径为R2，R2-R1的范围为3.0-5.0μm；所述内包层的半径为R3，R3-R2的范围为2-5μm；所述第一凹陷层的半径为R4，R4-R3的范围为2-8μm；所述掺杂层的半径为R5，R5-R4的范围为5-30μm；所述第二凹陷层的半径为R6，R6-R5的范围为10-22μm；所述外包层的半径R7为60-65μm。
在一种可能的实现方式中，所述低损耗单模光纤的应用波长范围为1310-1550nm。
在一种可能的实现方式中，所述低损耗单模光纤在应用波长1310nm处的模场直径为8.7-9.7μm；所述低损耗单模光纤在应用波长1550nm处的模场直径为9.5-10.5μm。
在一种可能的实现方式中，所述低损耗单模光纤在应用波长1310nm处的衰减系数≤0.350dB/km；所述低损耗单模光纤在应用波长1550nm处的衰减系数≤0.175dB/km。
在一种可能的实现方式中，所述低损耗单模光纤的零色散波长范围为1300-1324nm，所述低损耗单模光纤在零色散波长处的色散斜率≤0.092ps/(nm2*km)；所述低损耗单模光纤在应用波长1550nm处的色散系数≤18ps/(nm*km)。
本申请实施方式提供的一种低损耗单模光纤，其包括芯层和围绕于芯层外围的包层，芯层包括内芯层和外芯层，内芯层中掺杂有P、GeO2,外芯层中掺杂有F、P、GeO2。通过合理的光纤结构设计和芯层掺杂元素的控制，在芯棒剖面结构不变的前提下，减少瑞利散射，从而达到降低光纤衰减系数的目的；在光纤各项性能兼容G.652标准的前提下，使光纤具有更低的衰减损耗和更优的抗弯曲特性。
附图说明
为了更清楚地说明本申请实施方式或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作一简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施方式提供的低损耗单模光纤的横截面示意图；
图2为本申请实施方式提供的低损耗单模光纤的剖面结构示意图；
图3为本申请实施方式提供的实施例一的低损耗单模光纤的折射率分布示意图；
图4为本申请实施方式提供的实施例一的低损耗单模光纤的应力分布对比示意图；
图5为本申请实施方式提供的实施例四的低损耗单模光纤的折射率分布示意图；
图6为本申请实施方式提供的实施例五的低损耗单模光纤的折射率分布示意图；
图7为本申请实施方式提供的实施例六的低损耗单模光纤的折射率分布示意图。
附图标记：
100：内芯层；
200：外芯层；
300：内包层；
400：第一凹陷层；
500：掺杂层；
600：第二凹陷层；
700：外包层。
具体实施方式
正如背景技术中所阐述的，相关技术中的单模光纤有光纤衰减大的问题，经技术人员研究发现，出现这种问题的原因在于，现有低损耗弯曲不敏感单模光纤剖面设计为了平衡掺杂量、以及石英粘度实现较低的衰减，光纤芯层一般采用Ge元素和F元素共掺，由于F元素的掺杂降低了芯层折射率，需要掺杂更多的Ge才能保持芯层折射率不变，掺杂更多的GE将导致散射增加；同时低损耗截止波长位移单模光纤的衰减、色散参数、模场直径、缆波长等参数也受芯层结构的影响，现有的芯层剖面采用阶跃型设计，芯包层之间存在明显的应力突变，衰减偏高。且在调整芯层剖面结构时，各参数也都在同步变化，各项指标难以达到G.652标准(G.652标准指定了单模光纤(SMF)的特性和性能，包括模式分布、模分布常数、最大衰减、最大折射率变化、抗拉伸强度和热变形温度等)；为保证各参数兼容G.652标准，环芯凹陷层的深度和宽度设计值有限，光纤抗弯曲性能改善效果有限，难以达到G.657弯损标准。
另外，现有低损耗截止波长位移单模光纤在芯棒剖面定型后，直接匹配纯硅套管拉丝，截止波长迁移的位置不便再调整，导致预制棒拉制光纤适用波长范围较窄。针对上述技术问题，本申请实施方式提供了一种低损耗单模光纤，通过合理的光纤结构设计、芯层掺杂控制和外芯层掺杂控制，在光纤各项性能兼容G.652标准的前提下，使光纤具有更低的衰减损耗和更优的抗弯曲特性；同时，还能在芯棒剖面结构不变的前提下，通过调整匹配拉丝的掺F夹层管折射率高低控制截止波长迁移的位置，使得拉制光纤能够调整至不同的波长范围，并进一步提高弯曲性能。
为了使本申请实施方式的上述目的、特征和优点能够更加明显易懂，下面将结合本申请实施方式中的附图，对本申请实施方式中的技术方案进行清楚、完整地描述。显然，所描述的实施例仅仅是本申请的一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动的前提下所获得的所有其它实施例，均属于本申请保护的范围。
本申请实施方式提供了一种低损耗单模光纤，参考图1和图2，图1为本申请实施方式提供的低损耗单模光纤的横截面示意图，图2为本申请实施方式提供的低损耗单模光纤的剖面结构示意图；该低损耗单模光纤包括芯层和围绕于芯层外围的包层，芯层包括内芯层100和外芯层200，包层包括由中心至外周依次层叠设置的内包层300、第一凹陷层400、掺杂层500、第二凹陷层600以及外包层700；本申请实施例中，内芯层100的半径R1可以为2-6μm，外芯层200的半径为R2，R2-R1的范围为3.0-5.0μm；内包层300的半径为R3，R3-R2的范围为2-5μm；第一凹陷层400的半径为R4，R4-R3的范围为2-8μm；掺杂层500的半径为R5，R5-R4的范围为5-30μm；第二凹陷层600的半径为R6，R6-R5的范围为10-22μm；外包层700的半径R7为60-65μm，外包层700的半径R7可以为62.5μm。
通过在内芯层100中掺杂GeO2和P元素改变折射率，其中，内芯层100中掺杂有摩尔浓度为0.10-1.5％的GeO2和摩尔浓度为0.01-0.3％的P元素。
通过在外芯层200中掺杂GeO2、P元素和F元素改变折射率，其中，外芯层200中掺杂有摩尔浓度为0.10-1.5％的GeO2、摩尔浓度为0.01-0.3％的P元素和摩尔浓度为大于0且1.5％以下的F元素。
通过在内包层300中掺杂GeO2、P元素和F元素改变折射率，其中，内包层300中掺杂有摩尔浓度为0-0.2％的GeO2、摩尔浓度为0.01-0.3％的P元素和摩尔浓度为0.5-1.5％的F元素。
通过在第一凹陷层400中掺杂GeO2和F元素改变折射率，其中，第一凹陷层400中掺杂有摩尔浓度为0-0.2％的GeO2和摩尔浓度为0-2.0％的F元素。
通过在掺杂层500中掺杂GeO2和F元素改变折射率，其中，掺杂层500中掺杂有摩尔浓度为0-0.2％的GeO2和摩尔浓度为0-2.0％的F元素。
通过在第二凹陷层600中掺杂GeO2和F元素改变折射率，其中，第二掺杂层中掺杂有摩尔浓度为0-0.2％的GeO2和摩尔浓度为0-3.0％的F元素。
使得芯层的折射率呈现抛物线渐变型分布，能够实现物理性能和掺杂浓度的渐变，消除或减小芯包层间的界面应力差，还能在保持模场直径不变的情况下，降低1550色散值以满足G652标准要求。
需要说明的是，还能够使得内芯层100与外包层700之间的相对折射率差Δ1保持在0.10-0.25％之间，外芯层200与外包层700之间的相对折 射率差Δ2保持在0-0.20％之间，内包层300与外包层700之间的相对折射率差Δ3保持在-0.10至-0.30％之间，第一凹陷层400与外包层700之间的相对折射率差Δ4保持在-0.25至-0.50％之间，掺杂层500与外包层700之间的相对折射率差Δ5保持在-0.30至-0％之间，第二凹陷层600与外包层700之间的相对折射率差Δ6保持在-0.50-0％之间。
上述折射率能够使得单模光纤的应用波长范围保持在1310-1550nm之间。
其中，单模光纤在应用波长1310nm处时，其模场直径为8.7-9.7μm，优选模场直径为9.2μm，其衰减系数≤0.350dB/km，单模光纤在应用波长1310nm处时，其衰减系数也可以0.290dB/km。单模光纤在应用波长1550nm处时，其模场直径为9.5-10.5μm，优选模场直径为10.5μm，其衰减系数≤0.175dB/km；单模光纤在应用波长1550nm处时，其衰减系数也可以≤0.165dB/km。各项性能指标可兼容G.652和G.657A2标准。
上述折射率还能够使得单模光纤的零色散波长范围保持在1300-1324nm之间；其中，单模光纤在零色散波长处，其色散斜率≤0.092ps/(nm2*km)；单模光纤在应用波长1550nm处，其色散系数≤18ps/(nm*km)。
需要说明的是，掺杂P元素的摩尔浓度低于0.3％摩尔浓度，同时通过和F元素共掺能够基本消除P元素在1570nm吸收峰对光纤1530～1625波导衰减的影响。当掺杂P元素的摩尔浓度低于0.3％摩尔浓度，且掺杂P元素的单模光纤通过氘气处理后，单模光纤的抗氢老损性能和不掺杂P元素的普通单模光纤测试结果基本相同，符合标准要求。
同时，通过调节SiO2、GeO2、F元素和P元素在沉积过程中的流量比实现剖面结构设计；其中，GeO2掺杂的原则为尽量降低其掺杂量，以降低GeO2掺杂引起的瑞利散射损耗。由于芯层中微量P的掺杂替代了F掺杂对于芯层粘度调节的作用，在芯层和包层折射率差值不变的前提下，内芯层不掺F可进一步减少芯层掺GeO2的量，进而减少瑞利散射。
本申请实施方式的低损耗单模光纤包括芯层和围绕于芯层外围的包层，芯层包括内芯层100和外芯层200，包层包括由中心至外周依次层叠设置的内包层300、第一凹陷层400、掺杂层500、第二凹陷层600以及外包层700；内芯层100中掺杂有P、GeO2，外芯层200中掺杂有F、P、GeO2，内包层300 中掺杂有GeO2、P元素和F元素，第一凹陷层400中掺杂有GeO2和F元素，掺杂层500中掺杂有GeO2和F元素，第二凹陷层600中掺杂有GeO2和F元素。通过合理的光纤结构设计和芯层掺杂控制，在芯棒剖面结构不变的前提下，通过调整内芯层和外芯层中掺杂的元素减少瑞利散射，从而达到降低光纤衰减系数的目的。
同时，还通过调整匹配拉丝的掺F夹层管折射率高低控制截止波长迁移的位置，使得拉制光纤能够调整至不同的波长范围，在光纤各项性能兼容G.652标准的前提下，使光纤具有更低的衰减损耗和更优的抗弯曲特性。
需要说明的是，本申请实施方式提供的低损耗单模光纤在靠近外包层700的位置设有掺杂层500和第二凹陷层600，一方面可以在防止光功率泄漏的前提下，有效降低芯层折射率，降低GeO2掺杂引起的瑞利散射损耗；另一方面在保证芯棒折射率不变的情况下，通过第二凹陷层600折射率的高低调整，实现截止波长迁移位置可调，光纤在1260～1625nm(O+S+L波段)宽波长范围内可调整使用，降低了光纤预制棒差异化设计的制造工艺难度。
同时，除控制截止波长迁移的位置外，本申请实施例的低损耗单模光纤在其他主要性能(MFD，色散性能)和G652相匹配的前提下，截止波长可根据应用波段调整，得到最优的弯曲性能。
例如：O波段应用时，缆截止波长≤1260nm，C+L波段应用时，缆截止波长≤1530nm，S+C+L波段应用时，截止波长≤1420nm。
还需要说明的是，本申请实施方式提供的低损耗单模光纤的内芯层100和外芯层200通过微量掺P元素替代了F元素掺杂对于粘度调节的效果，在保持芯层折射率不变的情况下，有效降低芯层掺GE量，降低了瑞利散射。
进一步的，本申请实施方式提供的低损耗单模光纤，其芯层采用抛物线渐变型设计，能够实现物理性能和掺杂浓度的渐变，消除或减小芯包层间的界面应力差，还能在保持模场直径不变的情况下，降低1550色散值以满足G652标准要求。
本申请实施例中，外包层700为纯二氧化硅制成，其中不掺杂其他元素。
本申请实施例中，外芯层200为掺杂有GeO2、P元素和F元素的二氧化硅玻璃层。
本申请实施例中，该低损耗单模光纤适用于MCVD、PCVD等各种制造工艺或混合工艺。
本申请实施例中，该低损耗单模光纤的光缆截止波长迁移位置可调(≤1530nm)。
需要说明的是，单模光纤在应用波长1550nm处时，15mm半径-10圈的宏弯损耗≤0.03dB；10mm半径-1圈的宏弯损耗≤0.1dB，7.5mm半径-1圈的宏弯损耗≤0.5dB。
以下通过实施例一至实施例六对本申请的低损耗单模光纤进行详细说明。
采用改进管内化学气相沉积法MCVD或等离子化学气相沉积法PCVD工艺制备预制芯棒，其中，掺杂层500可以由掺F元素的石英基管构成，以掺F元素的石英管作为沉积基管，SiCl4和O2为SiO2的原料，SiF4、SF6、C2F6或CF4作为掺F元素的原料，GECl4作为掺GE元素的原料，POCl3为掺P元素的原料。
使用往返移动的氢氧喷灯或等离子体作为热源，通过控制管内各掺杂元素浓度，依次在掺F基管内表面沉积得到凹陷层、内包层、外芯层和内芯层；然后在高温下将沉积管熔缩到合适的内径，内径收死前通入SF6或C2F6和O2在氢氧喷灯或石墨炉加热下对内径表面粘附的杂质进行刻蚀去除，最终高温融缩为实心芯棒。
采用掺F石英套管作为第二凹陷层600和纯石英材质套管作为外包层700匹配拉丝，高温拉丝得到光纤。
光纤剖面结构包括内芯层100、外芯层200、内包层300、第一凹陷层400、掺杂层500、第二凹陷层600和外包层700，内芯层100的半径为R1，相对折射率差为Δ1；外芯层200的半径为R2，相对折射率差为Δ2；内包层300的半径为R3，相对折射率差为Δ3；第一凹陷层400的半径为R4，相对折射率差为Δ4；掺杂层500的半径为R5，相对折射率差为Δ5；第二凹陷层600的半径为R6，相对折射率差为Δ6；外包层700为纯二氧化硅，其半径R7为62.5μm，相对折射率差为0％。
表1不同结构设计光纤参数
表2不同结构设计光纤掺杂元素浓度分布
表3不同结构参数光纤的测试性能
MFD(模场直径)的检测标准：《GBT-15972.45-2008光纤试验方法规范第45部分：传输特性和光学特性的测量测试方法和试验程序模场直径》。
缆截止波长检测标准：《GBT-15972.44-2008光纤试验方法规范第44部分：传输特性和光学特性的测量测试方法和试验程序截止波长》。
衰减系数检测标准：《GBT-15972.40-2008光纤试验方法规范第40部分：传输特性和光学特性的测量测试方法和试验程序衰减》。
宏弯损耗检测标准：《GBT-15972.47-2008光纤试验方法规范第47部分：传输特性和光学特性的测量测试方法和试验程序宏弯损耗》。
色散检测标准：《GBT-15972.42-2008光纤试验方法规范第42部分：传输特性和光学特性的测量测试方法和试验程序波长色散》。
对实施例一至实施例六得到的光纤的抗氢老损性能进行测试，测试的方法见表4，测试的结果见表5。
表4抗氢老损检测方法
表5抗氢老损性能测试
对于实施例一：
内芯层100的半径R1为2.5μm，Δ1为0.14％；外芯层200的厚度R2-R1为3.8μm，Δ2为0％；内包层300的厚度R3-R2为2.5μm，Δ3为-0.22％；第一凹陷层400的厚度R4-R3为4.8μm，Δ4为-0.34％；掺杂层500的厚度R5-R4为7.9μm，相对折射率差为Δ5为-0.22％，第二凹陷层600的厚度R6-R5为20μm，相对折射率差为Δ6为-0.28％；外包层为纯二氧化硅，半径R7为62.5μm。
该拉丝光纤在1310nm处的模场直径为9.2μm，在1550nm处的模场直径为10.5μm，缆截止波长为1240nm，1310nm和1550nm衰减分别为0.288dB/km和0.163dB/km，零色散波长1314nm，零色散波长斜率0.087ps/(nm2*km)，1550nm色散值16.6ps/(nm*km)，光纤各项性能符合G652标准。
利用光纤折射率剖面测试仪表(扫描激光使用标准波长632nm)对实施例一中得到的光纤的折射率分布进行测试，得到其折射率分布图如图3所示。
利用光纤应力测试仪对实施例一中得到的光纤的应力分布进行测试，另在相同剖面设计下，对内/外芯层采用只掺F未掺P方式进行制备，两者光纤应力分布图比对如图4所示。
可以看出，在相同剖面设计下，相比芯层掺P光纤，掺F光纤为保证芯层折射率差值，芯层需要掺杂更多的GE，除了导致瑞利散射增加外，另芯层和下陷层之间的应力突变更明显。芯层掺P相比芯层掺F对于减少芯层和下陷层之间的应力不匹配效果更佳。
对于实施例二：
在实施例一的基础上折射率Δ1从0.14％降低至0.12％，其它结构参数和实施例一基本相同。该设计光纤降低芯层折射率后，零色散波长迁移至1318nm，零色散波长斜率0.087ps/(nm2*km)，1550nm色散值16.4ps/(nm*km)，1550nm衰减0.180dB/km增加明显，1310nm衰减0.285dB/km小幅度降低，缆截止波长降低至1120nm，R15*10@1550nm、R10*1@1550nm、R7.5*1@1550nm弯损增加明显，说明光信号在长波长存在泄漏。
对于模场直径较小的光纤设计，降低芯包层折射率差将导致基模的截止波长偏小而发生长波长输光泄露，需加宽或加深凹陷层或维持足够大的芯包层折射率差。
实施例三：
相比实施例一，实施例三中光纤各结构层对应的折射率参数基本保持不变，因内芯层采用Ge/F/P共掺方式，在芯层折射率保持不变的条件下，芯层掺Ge量相比增加，引起的瑞利散射损耗也增加，该设计光纤1310nm衰减和1550nm衰减增加至0.297dB/km和0.169dB/km，其他参数基本无变化。
实施例四：
相比实施例一，在芯层直径和高度保持不变的情况下，芯层改为阶跃式设计，芯层半高宽相比实施例一增加，另因芯包层应力突变加剧，弯损虽有降低，但1310nm衰减和1550nm衰减增加至0.304dB/km和0.178dB/km，缆波长增加至1340nm，零色散波长迁移至1298nm，零色散波长斜率0.093ps/(nm2*km)，1550nm色散值18.9ps/(nm*km)，光纤色散指标超出G652标准。
如图5所示，在相同芯层折射率差和保证模场直径不变的情况下，相比芯层抛物线渐变型设计，芯层阶跃型设计在衰减，色散控制方面存在较 明显不足。
实施例五：
参考图6及表格内容，相比实施例一，实施例五无第二凹陷层600设计，为防止光功率泄漏，芯层折射率增加0.19％，芯层掺Ge量相比增加，@1550nm衰减增加至0.172dB/km，缆波长无明显变化。零色散波长迁移至1308nm，零色散波长斜率0.090ps/(nm2*km)，1550nm色散值17.9ps/(nm*km)，光纤色散指标接近G652标准上限。
实施例六：
参考图7及表格内容，相比实施例一，实施例六无第二凹陷层600设计，为防止光功率泄漏和确保低弯曲损耗，第一凹陷层400宽度和深度分别增加到7.4μm和-0.42％，缆波长增加到1335nm超出G652标准上限，另模场直径减小到8.8μm接近标准下限，色散参数无明显变化。
综上所述，本申请实施方式的低损耗单模光纤包括芯层和围绕于芯层外围的包层，芯层包括内芯层100和外芯层200，包层包括由中心至外周依次层叠设置的内包层300、第一凹陷层400、掺杂层500、第二凹陷层600以及外包层700；内芯层100中掺杂有P、GeO2，外芯层200中掺杂有F、P、GeO2，内包层300中掺杂有GeO2、P元素和F元素，第一凹陷层400中掺杂有GeO2和F元素，掺杂层500中掺杂有GeO2和F元素，第二凹陷层600中掺杂有GeO2和F元素。通过合理的光纤结构设计和芯层掺杂控制，在芯棒剖面结构不变的前提下，通过调整内芯层和外芯层中掺杂的元素减少瑞利散射，从而达到降低光纤衰减系数的目的。
还通过调整匹配拉丝的掺F夹层管折射率高低控制截止波长迁移的位置，使得拉制光纤能够调整至不同的波长范围，在光纤各项性能兼容G.652标准的前提下，使光纤具有更低的衰减损耗和更优的抗弯曲特性。
进一步的，本申请实施方式提供的低损耗单模光纤采用抛物线渐变型设计，一方面可实现物理性能和掺杂浓度的渐变，消除或减小芯包层间的界面应力差，另一方面在保持模场直径不变的情况下，有效降低光纤零色散波长斜率和1550色散值，作为长距离干线传输光纤使用时，减少了色散补偿。
同时，本申请实施方式提供的低损耗单模光纤在靠近外包层700设有 第二凹陷层600，可以在防止光功率泄漏的前提下，有效降低了芯层折射率，降低GeO2掺杂引起的瑞利散射损耗，确保了光纤的低衰减损耗。
本说明书中各实施例或实施方式采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分相互参见即可。
应当指出，在说明书中提到的“一个实施例”、“实施例”、“示例性实施例”、“一些实施例”等表示所述的实施例可以包括特定特征、结构或特性，但未必每个实施例都包括该特定特征、结构或特性。此外，这样的短语未必是指同一实施例。此外，在结合实施例描述特定特征、结构或特性时，结合明确或未明确描述的其他实施例实现这样的特征、结构或特性处于本领域技术人员的知识范围之内。
一般而言，应当至少部分地由语境下的使用来理解术语。例如，至少部分地根据语境，文中使用的术语“一个或多个”可以用于描述单数的意义的任何特征、结构或特性，或者可以用于描述复数的意义的特征、结构或特性的组合。类似地，至少部分地根据语境，还可以将诸如“一”或“所述”的术语理解为传达单数用法或者传达复数用法。
应当容易地理解，应当按照最宽的方式解释本公开中的“在……上”、“在……以上”和“在……之上”，以使得“在……上”不仅意味着“直接处于某物上”，还包括“在某物上”且其间具有中间特征或层的含义，并且“在……以上”或者“在……之上”不仅包括“在某物以上”或“之上”的含义，还可以包括“在某物以上”或“之上”且其间没有中间特征或层(即，直接处于某物上)的含义。
此外，文中为了便于说明可以使用空间相对术语，例如，“下面”、“以下”、“下方”、“以上”、“上方”等，以描述一个元件或特征相对于其他元件或特征的如图所示的关系。空间相对术语意在包含除了附图所示的取向之外的处于使用或操作中的器件的不同取向。装置可以具有其他取向(旋转90度或者处于其他取向上)，并且文中使用的空间相对描述词可以同样被相应地解释。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通 技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (10)

  1. 一种低损耗单模光纤，其特征在于，包括芯层和围绕于所述芯层外围的包层，所述芯层包括内芯层和外芯层，所述内芯层中掺杂有P、GeO2,所述外芯层中掺杂有F、P、GeO2。
  2. 根据权利要求1所述的低损耗单模光纤，其特征在于，
    所述内芯层中掺杂有摩尔浓度为0.10-1.5％的GeO2和摩尔浓度为0.01-0.3％的P元素；
    所述外芯层中掺杂有摩尔浓度为0.10-1.5％的GeO2、摩尔浓度为0.01-0.3％的P元素和摩尔浓度为大于0且1.5％以下的F元素。
  3. 根据权利要求1所述的低损耗单模光纤，其特征在于，所述芯层的折射率呈抛物线渐变型分布。
  4. 根据权利要求1所述的低损耗单模光纤，其特征在于，所述包层包括由中心至外周依次层叠设置的内包层、第一凹陷层、掺杂层、第二凹陷层以及外包层；所述内包层中掺杂有摩尔浓度为0-0.2％的GeO2、摩尔浓度为0.01-0.3％的P元素和摩尔浓度为0.5-1.5％的F元素；
    所述第一凹陷层中掺杂有摩尔浓度为0-0.2％的GeO2和摩尔浓度为0-2.0％的F元素；
    所述掺杂层中掺杂有摩尔浓度为0-0.2％的GeO2和摩尔浓度为0-2.0％的F元素；
    所述第二凹陷层中掺杂有摩尔浓度为0-0.2％的GeO2和摩尔浓度为0-3.0％的F元素。
  5. 根据权利要求4所述的低损耗单模光纤，其特征在于，
    所述内芯层与所述外包层之间的相对折射率差Δ1为0.10至0.25％；
    所述外芯层与所述外包层之间的相对折射率差Δ2为0至0.20％；
    所述内包层与所述外包层之间的相对折射率差Δ3为-0.10至-0.30％；
    所述第一凹陷层与所述外包层之间的相对折射率差Δ4为-0.25至-0.50％；
    所述掺杂层与所述外包层之间的相对折射率差Δ5为-0.30至0％；
    所述第二凹陷层与所述外包层之间的相对折射率差Δ6为-0.50至0％。
  6. 根据权利要求4所述的低损耗单模光纤，其特征在于，
    所述内芯层的半径R1为2至6μm；
    所述外芯层的半径为R2，R2减去R1的范围为3至5μm；
    所述内包层的半径为R3，R3减去R2的范围为2至5μm；
    所述第一凹陷层的半径为R4，R4减去R3的范围为2至8μm；
    所述掺杂层的半径为R5，R5减去R4的范围为5至30μm；
    所述第二凹陷层的半径为R6，R6减去R5的范围为10至22μm；
    所述外包层的半径R7为60至65μm。
  7. 根据权利要求1所述的低损耗单模光纤，其特征在于，所述低损耗单模光纤的应用波长范围为1310-1550nm。
  8. 根据权利要求7所述的低损耗单模光纤，其特征在于，
    所述低损耗单模光纤在应用波长1310nm处的模场直径为8.7至9.7μm；
    所述低损耗单模光纤在应用波长1550nm处的模场直径为9.5至10.5μm。
  9. 根据权利要求7所述的低损耗单模光纤，其特征在于，所述低损耗单模光纤在应用波长1310nm处的衰减系数≤0.350dB/km；
    所述低损耗单模光纤在应用波长1550nm处的衰减系数≤0.175dB/km。
  10. 根据权利要求7所述的低损耗单模光纤，其特征在于，
    所述低损耗单模光纤的零色散波长范围为1300-1324nm，所述低损耗单模光纤在零色散波长处的色散斜率≤0.092ps/(nm2*km)；
    所述低损耗单模光纤在应用波长1550nm处的色散系数≤18ps/(nm*km)。
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CN117555068A (zh) * 2023-12-11 2024-02-13 中天科技精密材料有限公司 低损耗单模光纤

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