CN117518338A - Ultralow-loss large-effective-area optical fiber - Google Patents
Ultralow-loss large-effective-area optical fiber Download PDFInfo
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 96
- 239000010410 layer Substances 0.000 claims abstract description 161
- 238000005253 cladding Methods 0.000 claims abstract description 153
- 239000012792 core layer Substances 0.000 claims abstract description 60
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 43
- 230000000994 depressogenic effect Effects 0.000 claims abstract description 37
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 35
- 230000008859 change Effects 0.000 claims abstract description 31
- 230000007704 transition Effects 0.000 claims abstract description 26
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 23
- 239000011737 fluorine Substances 0.000 claims abstract description 23
- 229910052732 germanium Inorganic materials 0.000 claims abstract description 19
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims abstract description 19
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052796 boron Inorganic materials 0.000 claims abstract description 17
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000000460 chlorine Substances 0.000 claims abstract description 12
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 12
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 12
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 claims abstract 5
- 230000003287 optical effect Effects 0.000 claims description 16
- 230000003071 parasitic effect Effects 0.000 claims description 5
- 108700041286 delta Proteins 0.000 claims description 2
- 101000872084 Danio rerio Delta-like protein B Proteins 0.000 claims 1
- 239000000835 fiber Substances 0.000 abstract description 14
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 18
- 238000000034 method Methods 0.000 description 16
- LIQLLTGUOSHGKY-UHFFFAOYSA-N [B].[F] Chemical compound [B].[F] LIQLLTGUOSHGKY-UHFFFAOYSA-N 0.000 description 15
- 238000005452 bending Methods 0.000 description 11
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- HXELGNKCCDGMMN-UHFFFAOYSA-N [F].[Cl] Chemical compound [F].[Cl] HXELGNKCCDGMMN-UHFFFAOYSA-N 0.000 description 4
- 229910052783 alkali metal Inorganic materials 0.000 description 4
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- 238000005229 chemical vapour deposition Methods 0.000 description 4
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- 230000009471 action Effects 0.000 description 3
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- GLFAEFVIKYUOJK-UHFFFAOYSA-N [B].[Cl] Chemical compound [B].[Cl] GLFAEFVIKYUOJK-UHFFFAOYSA-N 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
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- 230000005856 abnormality Effects 0.000 description 1
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
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- 238000004364 calculation method Methods 0.000 description 1
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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
- G02B6/02004—Optical fibres with cladding with or without a coating characterised by the core effective area or mode field radius
- G02B6/02009—Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres
- G02B6/02014—Effective area greater than 60 square microns in the C band, i.e. 1530-1565 nm
- G02B6/02019—Effective area greater than 90 square microns in the C band, i.e. 1530-1565 nm
-
- 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
- G02B6/0283—Graded index region external to the central core segment, e.g. sloping layer or triangular or trapezoidal layer
-
- 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
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- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
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Abstract
The application relates to an ultralow-loss optical fiber with large effective area, which comprises a core layer, a first gradual change layer, an inner cladding layer, a second gradual change layer, a depressed cladding layer, a third gradual change layer, a transitional cladding layer, a fourth gradual change layer and an outer cladding layer which are sequentially arranged from inside to outside along the radial direction of the optical fiber; the core layer is silicon dioxide co-doped with chlorine and boron or co-doped with chlorine and fluorine, and is not doped with germanium; the first gradual change layer, the inner cladding layer, the second gradual change layer, the sinking cladding layer, the third gradual change layer, the transition cladding layer and the fourth gradual change layer are all silicon dioxide co-doped with fluorine and boron; the outer cladding is pure silica. The fiber attenuation problem caused by viscosity matching unbalance of the existing fiber structure can be solved while the fiber attenuation problem has ultralow loss and large effective area.
Description
Technical Field
The application relates to the technical field of optical fiber communication, in particular to an optical fiber with ultralow loss and large effective area.
Background
Today, people begin to pay attention to network learning and offices, and demands for optical transmission networks and cloud services are increasing. In a conventional intensity modulation-direct detection optical fiber communication system, main parameters that restrict the performance of the system include optical fiber loss, dispersion and nonlinearity. Currently, long-distance large-capacity optical communication transmission networks of 100G and 400G are becoming dominant in operator backbone networks. For long-distance optical fiber transmission systems, coherent optical communication systems are introduced to solve the problem of signal distortion caused by chromatic dispersion, however, high-order modulation methods are very sensitive to nonlinear effects, so that higher requirements are put on optical signal to noise ratio (OSNR).
OSNR refers to the ratio of the peak power to the noise power of an optical signal in the range of 0.1nm, where the size determines the signal quality, and improving the signal-to-noise ratio of an optical signal is the most straightforward and efficient way to improve the performance of an optical fiber transmission system. The optical signal-to-noise ratio calculation method of the optical communication system is shown as a formula (1), wherein the optical power P of the incoming fiber in the formula (1) ch Inversely proportional to the nonlinear coefficient nlc of the fiber (as shown in equation 2), and inversely proportional to the regeneration section loss S and the fiber attenuation coefficient α. Therefore, the effective area of the optical fiber is increased, the attenuation coefficient of the optical fiber is reduced, the optical signal to noise ratio of the optical transmission system can be increased, and the system quality is improved.
OSNR out ＝P ch /(S·P ph ·NF·N spans ) (1)
Wherein OSNR is out P is the optical signal to noise ratio of the optical transmission system ch For the power of the incoming light, S is the loss of the regeneration section, P ph For amplifier spontaneous emission noise, NF is the noise figure of the amplifier, N spans Is the number of spans of the system.
nlc＝n2/A eff (2)
Wherein n2 is the nonlinear refractive index of the transmission fiber, A eff Is the effective area of the transmission fiber.
Compared with the most widely used G.652.D optical fiber at present, the G.654 optical fiber with low loss and large effective area can effectively improve the transmission performance of the 400G/1T system. According to ITU, IEC and related industry standards, the G.654.A/B/C/D optical fibers are suitable for submarine optical cables, and in order to adapt to the complex environment of a land network, the G.654.E optical fibers are used for a backbone network, and the standard improves the requirement of bending performance. With the upgrading of the bandwidth of the backbone network, the preparation and technical research of the ultra-low-loss large-effective-area G.654.E optical fiber have become industry research hot spots.
The most important technology for preparing the ultralow attenuation optical fiber at present adopts a pure silicon core design, and the core layer is not doped with germanium Ge, so that a very low Rayleigh scattering coefficient can be obtained, and the reduced optical fiber attenuation is obtained. But to ensure total reflection of the fiber, a relatively low index fluorine doped inner cladding must be used for matching to ensure a sufficient index difference between the core and inner cladding. The viscosity of the pure silicon core part is relatively high, and the viscosity of the inner cladding part doped with a large amount of fluorine is relatively low, so that the viscosity matching unbalance of the optical fiber structure is caused, the superiority brought by concentration fluctuation reduction is counteracted, and the reverse abnormality of the optical fiber attenuation is more likely to be caused. It is therefore necessary to study a low loss, large effective area optical fiber that achieves good bending performance.
Some related art add an alkali metal to the core to change the viscosity of the core portion of the fiber, thereby reducing the rayleigh scattering coefficient of the fiber as a whole. Although the method can effectively reduce the attenuation of the optical fiber, the control requirement on the alkali metal doping concentration is extremely high, and the method is unfavorable for the large-scale preparation of the optical fiber. There are also some related art designs in which the core layer is designed with germanium/fluorine/alkali metal in order to match the viscosity between the core and cladding layers, and in addition to the problems associated with alkali metal, the low attenuation performance is difficult to achieve by re-introducing germanium.
Disclosure of Invention
The embodiment of the application provides an ultralow-loss optical fiber with a large effective area, which can solve the problem of optical fiber attenuation caused by viscosity matching unbalance of the existing optical fiber structure while having ultralow loss and large effective area.
The embodiment of the application provides an ultralow-loss large-effective-area optical fiber, which comprises a core layer, a first gradual change layer, an inner cladding layer, a second gradual change layer, a dip cladding layer, a third gradual change layer, a transitional cladding layer, a fourth gradual change layer and an outer cladding layer which are sequentially arranged from inside to outside along the radial direction of the optical fiber;
the core layer is silicon dioxide co-doped with chlorine and boron or co-doped with chlorine and fluorine, and is not doped with germanium;
the first gradual change layer, the inner cladding layer, the second gradual change layer, the sinking cladding layer, the third gradual change layer, the transition cladding layer and the fourth gradual change layer are all silicon dioxide co-doped with fluorine and boron;
the outer cladding is pure silica.
In some embodiments, the contribution amount Δcl of chlorine in the core layer to the relative refractive index difference is 0.10% -0.20%, and the contribution amount Δb or Δf of boron or fluorine in the core layer to the relative refractive index difference is-0.1% -0.05%.
In some embodiments, the relative refractive index difference Δ1 of the core layer with respect to pure silica, the relative refractive index difference Δ3 of the inner cladding layer with respect to pure silica, the relative refractive index difference Δ5 of the depressed cladding layer with respect to pure silica, the relative refractive index difference Δ7 of the transition cladding layer with respect to pure silica, and the relative refractive index difference Δ9 of the outer cladding layer with respect to pure silica satisfy: Δ1 > Δ9 > Δ7 > Δ3 > Δ5.
In some embodiments, the core layer has a relative refractive index difference Δ1 of 0.05 to 0.20%;
the relative refractive index difference delta 2 of the first graded layer is between the relative refractive index differences of the core layer and the inner cladding layer;
the relative refractive index difference delta 3 of the inner cladding is-0.25 to-0.22%;
the relative refractive index difference delta 4 of the second graded layer is between the relative refractive index differences of the inner cladding layer and the depressed cladding layer;
the relative refractive index difference delta 5 of the depressed cladding is-0.45 to-0.38 percent;
the relative refractive index difference delta 6 of the third graded layer is between the relative refractive index differences of the depressed cladding and the transitional cladding;
the relative refractive index difference delta 7 of the transition cladding is-0.15 to-0.09 percent;
the relative refractive index difference delta 8 of the fourth graded layer is between the relative refractive index differences of the transition cladding and the outer cladding;
the relative refractive index difference Δ9 of the overclad layer is 0.
In some embodiments, the radius R1 of the core layer is 5.2-6.2 um;
the radius R2 of the first gradual change layer is 7.6-8.6 um;
the radius R3 of the inner cladding is 12.4-14.4 um;
the radius R4 of the second gradual change layer is 15.8-16.8 um;
the radius R5 of the depressed cladding is 20.5-30.5 um;
the radius R6 of the third gradual change layer is 31.3-32.3 um;
the radius R7 of the transition cladding is 46.3-57.3 um;
the radius R8 of the fourth gradual change layer is 58.1-59.2 um;
the radius R9 of the outer cladding is 125um.
In some embodiments, the optical fiber has an attenuation coefficient at 1310nm wavelength of less than or equal to 0.25dB/km.
In some embodiments, the optical fiber has an attenuation coefficient at a wavelength of 1550nm of less than or equal to 0.16dB/km; the mode field diameter at 1550nm is 12.0 um-12.4 um; the effective area of the optical fiber at 1550nm wavelength is 120-145 um 2 。
In some embodiments, the optical fiber has a cable cutoff wavelength less than or equal to 1520nm.
In some embodiments, the optical fiber has a bend parasitic loss of less than or equal to 0.02dB at a wavelength of 1550nm, when wrapped 100 turns around a 30mm bend radius.
In some embodiments, the fiber has a bend loss at 1625nm of less than or equal to 0.03dB when wrapped around a 30mm bend radius for 100 turns.
The beneficial effects that technical scheme that this application provided brought include:
the embodiment of the application provides an ultralow-loss large-effective-area optical fiber, in the application, a core layer is not doped with germanium, and a graded layer is added between the core layer and a cladding layer and between two adjacent cladding layers, so that refractive indexes between the two layers are slowly changed according to a certain slope, the interface viscosity matching of the core layer is optimized, and the optical fiber attenuation caused by the unbalance of the structural viscosity matching of the optical fiber is reduced. Meanwhile, in order to solve the bending loss problem, fluorine and boron are doped in each graded layer and each cladding except the outer cladding, so that the depressed cladding obtains a lower refractive index value, and the situation that the refractive index difference between the core layer and the depressed cladding is reduced after the core layer is not doped with germanium element, so that the bending loss of the optical fiber is increased is avoided; it can be seen that compared with fluorine or boron doped alone, the refractive index reduced by fluorine-boron co-doping is higher, a depressed layer with a lower refractive index can be prepared, so that the optical fiber has a sufficiently small cabled cut-off wavelength, and the bending performance degradation of the optical fiber can be effectively suppressed by increasing the core-in relative refractive index difference.
Further, the core layer is subjected to chlorine boron co-doping or chlorine fluorine co-doping under the condition of not doping germanium element, and the viscosity of each part of the optical fiber and the stress of the optical fiber are optimized by matching with the graded layer and the cladding of each fluorine boron co-doping, so that the ultralow attenuation performance of the single-mode optical fiber is realized.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic cross-sectional view of an ultralow-loss large-effective-area optical fiber provided by an embodiment of the present application;
fig. 2 is a refractive index profile of an ultralow-loss large-effective-area optical fiber according to an embodiment of the present application.
In the figure: 1. a core layer; 2. a first graded layer; 3. an inner cladding; 4.a second graded layer; 5. sinking the cladding; 6. a third graded layer; 7. a transition cladding; 8. a fourth graded layer; 9. and an outer cladding.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.
Referring to fig. 1, an embodiment of the present application provides an ultralow-loss optical fiber with a large effective area, which includes a core layer 1, a first graded layer 2, an inner cladding layer 3, a second graded layer 4, a depressed cladding layer 5, a third graded layer 6, a transitional cladding layer 7, a fourth graded layer 8 and an outer cladding layer 9, which are sequentially disposed from inside to outside along the radial direction of the optical fiber; wherein the core layer 1 is silicon dioxide co-doped with chlorine and boron or co-doped with chlorine and fluorine, and is not doped with germanium; the first graded layer 2, the inner cladding layer 3, the second graded layer 4, the depressed cladding layer 5, the third graded layer 6, the transition cladding layer 7 and the fourth graded layer 8 are all silicon dioxide co-doped with fluorine and boron; the outer cladding 9 is pure silica.
The principle of the application is as follows:
typically, to reduce the attenuation of the fiber, the amount of Ge doping in the core layer is reduced or directly undoped. In preparing an optical fiber preform without germanium, a large amount of fluorine is generally doped in the cladding to lower the refractive index of the cladding, resulting in a depressed cladding refractive index profile structure. However, the germanium element can increase the refractive index of the core layer, so that the refractive index difference between the core layer and the depressed cladding is in a certain range, and when the germanium element is not doped, the refractive index of the core layer is reduced, and the refractive index difference between the core layer and the depressed cladding is reduced, so that the bending loss of the optical fiber is increased to a certain extent. It can be seen that the attenuation of the optical fiber can be reduced without doping germanium element, but the bending loss of the optical fiber can be increased to a certain extent.
Therefore, in order to reduce the attenuation of the optical fiber and avoid increasing the bending loss of the optical fiber, in the application, the core layer is not doped with germanium element, and meanwhile, a gradual change layer is added between the core layer and the cladding layer and between two adjacent cladding layers, so that the refractive indexes between the two layers are slowly changed according to a certain slope, the interface viscosity matching of the core layer is optimized, and the attenuation of the optical fiber caused by the unbalance of the structural viscosity matching of the optical fiber is reduced. Meanwhile, in order to solve the bending loss problem, fluorine and boron are doped in each graded layer and each cladding except the outer cladding, so that the depressed cladding obtains a lower refractive index value, and the situation that the refractive index difference between the core layer and the depressed cladding is reduced after the core layer is not doped with germanium element, so that the bending loss of the optical fiber is increased is avoided; it can be seen that compared with fluorine or boron doped alone, the refractive index reduced by fluorine-boron co-doping is higher, a depressed layer with a lower refractive index can be prepared, so that the optical fiber has a sufficiently small cabled cut-off wavelength, and the bending performance degradation of the optical fiber can be effectively suppressed by increasing the core-in relative refractive index difference.
Further, the core layer is subjected to chlorine boron co-doping or chlorine fluorine co-doping under the condition of not doping germanium element, and the viscosity of each part of the optical fiber and the stress of the optical fiber are optimized by matching with the graded layer and the cladding of each fluorine boron co-doping, so that the ultralow attenuation performance of the single-mode optical fiber is realized.
In summary, in the present application, the core layer 1 is not doped with germanium, but is co-doped with chlorofluoro or chloroboro, so that attenuation caused by rayleigh scattering can be reduced, and simultaneously, the refractive index of the inner cladding and the matched depressed cladding outside the inner cladding are adjusted to realize the restraint effect on the transmission light in the core layer.
And each graded layer is subjected to fluorine-boron co-doping, so that stress caused by unbalance of physical properties of two adjacent layers can be remarkably reduced or eliminated.
The inner cladding 3 is co-doped with fluorine and boron, so that the distance between the core 1 and the depressed cladding 5 can be controlled.
The depressed cladding 5 carries out fluorine-boron co-doping, and as the refractive index of the core layer is reduced, the MFD value of the mode field of the optical fiber is reduced, the deeper depressed cladding can improve the light restriction capacity in the core layer and increase the cut-off wavelength lambada c, and the effect of relieving the light power leakage is achieved to a certain extent.
The transitional cladding 7 is subjected to fluorine-boron co-doping, so that the optical fiber lambdac is effectively controlled, and the macrobending performance is obviously improved along with the increase of the width/depth of the transitional cladding 7.
The outer cladding 9 adopts the design of pure silicon dioxide, so that the specific gravity in the fluorine-boron doped glass is reduced, and the manufacturing cost of the optical fiber is reduced.
Further, in the present application, the contribution amount Δcl of chlorine in the core layer 1 to the relative refractive index difference is 0.10% to 0.20%, and the contribution amount Δb or Δf of boron or fluorine in the core layer 1 to the relative refractive index difference is-0.1% to-0.05%.
Wherein, the relative refractive index difference Δi is calculated by the following formula:
Δi＝(n-n 9 )/n 9 *100％
wherein n is 9 The refractive index of the outer cladding 9 being pure silica, for the purposes of this application, when calculating the relative refractive index difference Δ1 of the core 1 and pure silica, where n is the refractive index of the core 1; when calculating the relative refractive index difference delta 2 between the first graded layer 2 and pure silicon dioxide, n is the refractive index of the first graded layer 2; the other layers and so on.
Further, in the present application, the relative refractive index difference Δ1 of the core layer 1 with respect to pure silica, the relative refractive index difference Δ3 of the inner cladding layer 3 with respect to pure silica, the relative refractive index difference Δ5 of the depressed cladding layer 5 with respect to pure silica, the relative refractive index difference Δ7 of the transition cladding layer 7 with respect to pure silica, and the relative refractive index difference Δ9 of the outer cladding layer 9 with respect to pure silica satisfy: Δ1 > Δ9 > Δ7 > Δ3 > Δ5;
specifically, referring to fig. 2, the relative refractive index difference Δ1 of the core layer 1 is 0.05-0.20%, and the radius R1 of the core layer 1 is 5.2-6.2 um;
the relative refractive index difference delta 2 of the first graded layer 2 is between the relative refractive index differences of the core layer 1 and the inner cladding layer 3, and the radius R2 of the first graded layer 2 is 7.6-8.6 um;
the relative refractive index difference delta 3 of the inner cladding layer 3 is-0.25 to-0.22 percent, and the radius R3 of the inner cladding layer 3 is 12.4 to 14.4um;
the relative refractive index difference delta 4 of the second graded layer 4 is between the relative refractive index differences of the inner cladding layer 3 and the depressed cladding layer 5, and the radius R4 of the second graded layer 4 is 15.8-16.8 um;
the relative refractive index difference delta 5 of the depressed cladding 5 is-0.45 to-0.38 percent, and the radius R5 of the depressed cladding 5 is 20.5-30.5 um;
the relative refractive index difference delta 6 of the third graded layer 6 is between the relative refractive index differences of the depressed cladding 5 and the transition cladding 7, and the radius R6 of the third graded layer 6 is 31.3-32.3 um;
the relative refractive index difference delta 7 of the transition cladding 7 is-0.15 to-0.09 percent, and the radius R7 of the transition cladding 7 is 46.3 to 57.3um;
the relative refractive index difference delta 8 of the fourth graded layer 8 is between the relative refractive index differences of the transition cladding 7 and the outer cladding 9, and the radius R8 of the fourth graded layer 8 is 58.1-59.2 um;
the relative refractive index difference delta 9 of the outer cladding 9 is 0, and the radius R9 of the outer cladding 9 is 125um.
In this application, the attenuation coefficient of the fiber at 1310nm wavelength is less than or equal to 0.25dB/km.
The attenuation coefficient of the optical fiber at 1550nm wavelength is less than or equal to 0.16dB/km; the mode field diameter at 1550nm is 12.0 um-12.4 um; the effective area of the optical fiber at 1550nm wavelength is 120-145 um 2 。
The optical cable cut-off wavelength of the optical fiber is less than or equal to 1520nm.
The optical fiber has a bend parasitic loss of less than or equal to 0.02dB when wrapped 100 turns around a 30mm bend radius at a wavelength of 1550 nm.
The optical fiber has a bend parasitic loss of less than or equal to 0.03dB when wrapped 100 turns around a 30mm bend radius at a wavelength of 1625 nm.
Therefore, the comprehensive performance parameters such as the cut-off wavelength, the mode field diameter, the loss coefficient, the chromatic dispersion and the like of the optical fiber are good in application wave bands, and the G.654.E optical fiber standard is met.
Example 1:
an ultra-low loss large effective area G.654.E optical fiber comprises a core layer 1, a first graded layer 2, an inner cladding layer 3, a second graded layer 4, a dip cladding layer 5, a third graded layer 6, a transition cladding layer 7, a fourth graded layer 8 and an outer cladding layer 9 which are sequentially arranged from inside to outside along the radial direction of the optical fiber; wherein the core layer 1 is chlorofluoro co-doped silicon dioxide and is not doped with germanium; the first graded layer 2, the inner cladding layer 3, the second graded layer 4, the depressed cladding layer 5, the third graded layer 6, the transition cladding layer 7 and the fourth graded layer 8 are all silicon dioxide co-doped with fluorine and boron; the outer cladding 9 is pure silica.
The relative refractive index difference delta 1 of the core layer 1 is 0.10%, and the radius R1 of the core layer 1 is 5.4um;
the relative refractive index difference delta 2 of the first graded layer 2 is between the relative refractive index differences of the core layer 1 and the inner cladding layer 3, and the radius R2 of the first graded layer 2 is 8.1um;
the relative refractive index difference delta 3 of the inner cladding layer 3 is-0.23%, and the radius R3 of the inner cladding layer 3 is 13.4um;
the relative refractive index difference delta 4 of the second graded layer 4 is between the relative refractive index differences of the inner cladding layer 3 and the depressed cladding layer 5, and the radius R4 of the second graded layer 4 is 16.5um;
the relative refractive index difference delta 5 of the depressed cladding 5 is-0.42%, and the radius R5 of the depressed cladding 5 is 25.5um;
the relative refractive index difference delta 6 of the third graded layer 6 is between the relative refractive index differences of the depressed cladding 5 and the transition cladding 7, and the radius R6 of the third graded layer 6 is 31.7um;
the relative refractive index difference delta 7 of the transition cladding 7 is-0.13%, and the radius R7 of the transition cladding 7 is 52.3um;
the relative refractive index difference delta 8 of the fourth graded layer 8 is between the relative refractive index differences of the transition cladding 7 and the outer cladding 9, and the radius R8 of the fourth graded layer 8 is 58.5um;
the relative refractive index difference delta 9 of the outer cladding 9 is 0, and the radius R9 of the outer cladding 9 is 125um.
The optical fiber is prepared according to the following steps:
the deposition sequence of each layer of the optical fiber preform rod is sequentially deposited from inside to outside.
And preparing the chlorofluoro co-doped core quartz rod by adopting a VAD process. Firstly, depositing on a target rod to obtain a silicon dioxide powder rod with uniform outer diameter; and then carrying out high-temperature sintering treatment on the silicon dioxide powder rod, introducing a fluorine source in the high-temperature sintering process, then introducing helium and chlorine at the temperature ranging from 1200 ℃ to 1300 ℃ for purification, continuing to introduce the fluorine source after purification, then sintering the fluorine-chlorine co-doped core layer glass body at the temperature of 1500 ℃, and then stretching the chlorine-fluorine co-doped core layer glass body to the target size at high temperature to obtain the core layer quartz rod.
And preparing the fluorine-boron doped quartz sleeve by adopting an MCVD process. The oxygen-enriched carrier gas brings the fluorine boron into the quartz tube for fluorine boron doping, the refractive index depth of the fluorine boron doping reaches at least below absolute refractive index-0.0075 (relative refractive index is-0.510%), and the refractive index range/average value of the whole rod is controlled within 1.2%.
And assembling the core layer quartz rod into the fluorine-boron doped quartz sleeve by adopting a RIT process, purifying the interface between the core layer quartz rod and the fluorine-boron doped quartz sleeve at high temperature, and fusing the interface by vacuumizing.
Finally, preparing an outer cladding powder part by adopting an OVD process to obtain the preform.
The inner cladding part, the gradual change layer part, the depressed cladding part and the transitional cladding part in the fluorine-boron doped quartz sleeve are prepared by adopting one or a plurality of mixed processes of VAD (axial vapor deposition), MCVD (chemical vapor deposition), PCVD (plasma chemical vapor deposition) and OVD (outside vapor deposition).
And finally, carrying out wire drawing treatment on the prepared preform, enabling the preform to enter a wire drawing furnace from the top of the wire drawing furnace to form an optical fiber, gradually reducing the temperature in an annealing heat preservation furnace with the temperature gradient of 900-1000 ℃, basically releasing internal stress, coating and solidifying the optical fiber, and then finishing the processing through a screening procedure to obtain a finished optical fiber.
The prepared optical fiber is subjected to performance tests of attenuation performance, dispersion slope, mode field diameter, cut-off wavelength, effective area and the like of different wavebands, and the test results are shown in the following table 1:
TABLE 1
In the description of the present application, it should be noted that the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of description of the present application and simplification of the description, and are not indicative or implying that the apparatus or element in question must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present application. Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.
It should be noted that in this application, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing is merely a specific embodiment of the application to enable one skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The ultra-low loss large effective area optical fiber is characterized by comprising a core layer (1), a first gradual change layer (2), an inner cladding layer (3), a second gradual change layer (4), a dip cladding layer (5), a third gradual change layer (6), a transition cladding layer (7), a fourth gradual change layer (8) and an outer cladding layer (9) which are sequentially arranged from inside to outside along the radial direction of the optical fiber;
the core layer (1) is silicon dioxide co-doped with chlorine and boron or co-doped with chlorine and fluorine, and is not doped with germanium;
the first graded layer (2), the inner cladding layer (3), the second graded layer (4), the dip cladding layer (5), the third graded layer (6), the transition cladding layer (7) and the fourth graded layer (8) are silicon dioxide co-doped with fluorine and boron;
the outer cladding (9) is pure silica.
2. The ultra-low loss large effective area optical fiber of claim 1, wherein: the contribution quantity DeltaCl of chlorine in the core layer (1) to the relative refractive index difference is 0.10% -0.20%, and the contribution quantity DeltaB or DeltaF of boron or fluorine in the core layer (1) to the relative refractive index difference is-0.1% -0.05%.
3. The ultra-low loss large effective area optical fiber of claim 1, wherein: the relative refractive index difference Δ1 of the core layer (1) with respect to pure silica, the relative refractive index difference Δ3 of the inner cladding layer (3) with respect to pure silica, the relative refractive index difference Δ5 of the depressed cladding layer (5) with respect to pure silica, the relative refractive index difference Δ7 of the transition cladding layer (7) with respect to pure silica, and the relative refractive index difference Δ9 of the outer cladding layer (9) with respect to pure silica satisfy: Δ1 > Δ9 > Δ7 > Δ3 > Δ5.
4. The ultra-low loss large effective area optical fiber of claim 3, wherein:
the relative refractive index difference delta 1 of the core layer (1) is 0.05-0.20%;
the relative refractive index difference delta 2 of the first graded layer (2) is between the relative refractive index differences of the core layer (1) and the inner cladding layer (3);
the relative refractive index difference delta 3 of the inner cladding (3) is-0.25 to-0.22%;
the relative refractive index difference delta 4 of the second graded layer (4) is between the relative refractive index differences of the inner cladding (3) and the depressed cladding (5);
the relative refractive index difference delta 5 of the depressed cladding (5) is-0.45 to-0.38%;
the relative refractive index difference delta 6 of the third graded layer (6) is between the relative refractive index differences of the depressed cladding (5) and the transition cladding (7);
the relative refractive index difference delta 7 of the transition cladding (7) is-0.15 to-0.09%;
the relative refractive index difference delta 8 of the fourth graded layer (8) is between the relative refractive index differences of the transition cladding (7) and the outer cladding (9);
the relative refractive index difference delta 9 of the outer cladding (9) is 0.
5. The ultra-low loss large effective area optical fiber of claim 1, wherein:
the radius R1 of the core layer (1) is 5.2-6.2 um;
the radius R2 of the first gradual change layer (2) is 7.6-8.6 um;
the radius R3 of the inner cladding (3) is 12.4-14.4 um;
the radius R4 of the second gradual change layer (4) is 15.8-16.8 um;
the radius R5 of the depressed cladding (5) is 20.5-30.5 um;
the radius R6 of the third gradual change layer (6) is 31.3-32.3 um;
the radius R7 of the transition cladding (7) is 46.3-57.3 um;
the radius R8 of the fourth gradual change layer (8) is 58.1-59.2 um;
the radius R9 of the outer cladding layer (9) is 125um.
6. The ultra-low loss large effective area optical fiber of claim 1, wherein: the attenuation coefficient of the optical fiber at 1310nm wavelength is less than or equal to 0.25dB/km.
7. The ultra-low loss large effective area optical fiber of claim 1, wherein: the attenuation coefficient of the optical fiber at 1550nm wavelength is less than or equal to 0.16dB/km; the mode field diameter at 1550nm is 12.0 um-12.4 um; the effective area of the optical fiber at 1550nm wavelength is 120-145 um 2 。
8. The ultra-low loss large effective area optical fiber of claim 1, wherein: the optical cable cut-off wavelength of the optical fiber is less than or equal to 1520nm.
9. The ultra-low loss large effective area optical fiber of claim 1, wherein: the optical fiber has a bend parasitic loss of less than or equal to 0.02dB when wrapped 100 turns around a 30mm bend radius at a wavelength of 1550 nm.
10. The ultra-low loss large effective area optical fiber of claim 1, wherein: the optical fiber has a bend parasitic loss of less than or equal to 0.03dB when wrapped 100 turns around a 30mm bend radius at a wavelength of 1625 nm.
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