An ultra-low-loss large-effective-area optical fiber

Abstract

The application relates to an ultra-low-loss large-effective-area optical fiber, which comprises, from inside to outside along the radial direction of the optical fiber, a core layer, a first gradient layer, an inner cladding layer, a second gradient layer, a sunken cladding layer, a third gradient layer, a transition cladding layer, a fourth gradient layer and an outer cladding layer; the core layer is chlorine-boron co-doped or chlorine-fluorine co-doped silica and is not doped with germanium; the first gradient layer, the inner cladding layer, the second gradient layer, the sunken cladding layer, the third gradient layer, the transition cladding layer and the fourth gradient layer are all fluorine-boron co-doped silica; and the outer cladding layer is pure silica. The application can solve the optical fiber attenuation problem caused by the viscosity imbalance of the existing optical fiber structure while having ultra-low loss and large effective area.

Description

Technical Field

[0001] This application relates to the field of optical fiber communication technology, and in particular to an ultra-low loss optical fiber with a large effective area. Background Technology

[0002] Today, people are increasingly valuing online learning and work, leading to a growing demand for optical transmission networks and cloud services. In traditional intensity modulation-direct detection optical fiber communication systems, the main parameters limiting system performance include fiber loss, dispersion, and nonlinearity. Currently, 100G and 400G long-distance, high-capacity optical communication transmission networks are becoming the dominant backbone networks for operators. For long-distance optical fiber transmission systems, coherent optical communication systems are introduced to address signal distortion caused by dispersion. However, higher-order modulation methods are highly sensitive to nonlinear effects, thus placing higher demands on the optical signal-to-noise ratio (OSNR).

[0003] OSNR refers to the ratio of peak optical signal power to noise power within an effective bandwidth of 0.1 nm. Its magnitude determines the signal quality, and improving the signal-to-noise ratio of the optical signal is the most direct and effective way to improve the performance of the optical fiber transmission system. The calculation method of optical signal-to-noise ratio of optical communication system is shown in Equation (1), where the input optical power P in Equation (1) is... ch The attenuation coefficient is inversely proportional to the nonlinear coefficient nlc of the optical fiber (as shown in Equation 2), and also inversely proportional to the regeneration section loss S and the optical fiber attenuation coefficient α. Therefore, increasing the effective area of ​​the optical fiber while reducing its attenuation coefficient can increase the optical signal-to-noise ratio of the optical transmission system and improve system quality.

[0004] OSNR out =P ch / (S·P ph ·NF·N spans (1)

[0005] Among them, OSNR out P represents the optical signal-to-noise ratio of the optical transmission system. ch S is the input optical power, S is the loss of the regenerator section, and P is the input optical power. ph N is the amplifier's spontaneous emission noise, NF is the amplifier's noise figure, and N is the amplifier's noise figure. spans This represents the number of segments in the system.

[0006] nlc = n2 / A eff (2)

[0007] Where n2 is the nonlinear refractive index of the transmission optical fiber, and A eff It is the effective area of ​​the transmission optical fiber.

[0008] Compared to the most widely used G.652.D fiber, G.654 fiber, with its low loss and large effective area characteristics, can effectively improve the transmission performance of 400G / 1T systems. According to ITU, IEC, and related industry standards, G.654.A / B / C / D fibers are all suitable for submarine cables. To adapt to the complex environment of terrestrial networks, the standards for G.654.E fiber used in backbone networks have raised the requirements for its bending performance. With the upgrading of backbone network bandwidth, the fabrication and technical research of ultra-low loss, large effective area G.654.E fiber has become a research hotspot in the industry.

[0009] Currently, the most common process for fabricating ultra-low attenuation optical fibers is the use of a pure silicon core design. This design, because the core layer lacks germanium (Ge) doping, achieves a very low Rayleigh scattering coefficient, thus reducing fiber attenuation. However, to ensure total internal reflection, a fluorine-doped inner cladding with a relatively low refractive index must be used for matching, ensuring a sufficient refractive index difference between the core and the inner cladding. This results in a relatively high viscosity in the pure silicon core and a low viscosity in the heavily fluorine-doped inner cladding, causing a viscosity mismatch in the fiber structure. This not only negates the advantages of reduced concentration fluctuations but may also lead to reverse attenuation anomalies. Therefore, it is essential to research a low-loss optical fiber with good bending performance and a large effective area.

[0010] Some related technologies involve adding alkali metals to the core layer to alter the viscosity of the fiber core, thereby reducing the overall Rayleigh scattering coefficient. While this method effectively reduces fiber attenuation, the alkali metal doping concentration requires extremely precise control, hindering large-scale fiber fabrication. Other related technologies employ a germanium / fluorine / alkali metal design in the core layer to match the viscosity between the core and cladding. However, besides the problems introduced by alkali metals, the reintroduction of germanium in this approach makes it difficult to achieve the required low-attenuation performance. Summary of the Invention

[0011] This application provides an ultra-low loss optical fiber with a large effective area. While having both ultra-low loss and a large effective area, it can solve the optical fiber attenuation problem caused by viscosity mismatch in existing optical fiber structures.

[0012] This application provides an ultra-low loss optical fiber with a large effective area, which includes a core layer, a first graded layer, an inner cladding layer, a second graded layer, a recessed cladding layer, a third graded layer, a transition cladding layer, a fourth graded layer, and an outer cladding layer arranged sequentially from the inside to the outside along the radial direction of the optical fiber.

[0013] The core layer is silicon dioxide co-doped with boron chlorine or co-doped with fluorine chlorine, and is not doped with germanium;

[0014] The first gradient layer, inner cladding layer, second gradient layer, sunken cladding layer, third gradient layer, transition cladding layer and fourth gradient layer are all fluorine-boron co-doped silicon dioxide;

[0015] The outer cladding layer is pure silicon dioxide.

[0016] In some embodiments, the contribution of chlorine to the relative refractive index difference, ΔCl, in the core layer is 0.10% to 0.20%, and the contribution of boron or fluorine to the relative refractive index difference, ΔB or ΔF, in the core layer is -0.1% to -0.05%.

[0017] In some embodiments, the relative refractive index difference Δ1 of the core layer relative to pure silicon dioxide, the relative refractive index difference Δ3 of the inner cladding layer relative to pure silicon dioxide, the relative refractive index difference Δ5 of the recessed cladding layer relative to pure silicon dioxide, the relative refractive index difference Δ7 of the transition cladding layer relative to pure silicon dioxide, and the relative refractive index difference Δ9 of the outer cladding layer relative to pure silicon dioxide satisfy the following: Δ1 > Δ9 > Δ7 > Δ3 > Δ5.

[0018] In some embodiments, the relative refractive index difference Δ1 of the core layer is 0.05 to 0.20%;

[0019] The relative refractive index difference Δ2 of the first graded layer is between the relative refractive index difference between the core layer and the inner cladding layer;

[0020] The relative refractive index difference Δ3 of the inner cladding is -0.25 to -0.22%.

[0021] The relative refractive index difference Δ4 of the second graded layer is between the relative refractive index difference between the inner cladding and the sunken cladding;

[0022] The relative refractive index difference Δ5 of the sunken cladding is -0.45 to -0.38%.

[0023] The relative refractive index difference Δ6 of the third graded layer is between the relative refractive index difference of the sunken cladding and the transition cladding;

[0024] The relative refractive index difference Δ7 of the transition cladding is -0.15 to -0.09%.

[0025] The relative refractive index difference Δ8 of the fourth graded layer is between the relative refractive index difference of the transition cladding and the outer cladding;

[0026] The relative refractive index difference Δ9 of the outer cladding is 0.

[0027] In some embodiments, the radius R1 of the core layer is 5.2–6.2 μm;

[0028] The radius R2 of the first gradient layer is 7.6–8.6 μm;

[0029] The radius R3 of the inner cladding is 12.4–14.4 μm;

[0030] The radius R4 of the second gradient layer is 15.8–16.8 μm;

[0031] The radius R5 of the sunken cladding is 20.5–30.5 μm;

[0032] The radius R6 of the third gradient layer is 31.3–32.3 μm;

[0033] The radius R7 of the transition cladding is 46.3–57.3 μm;

[0034] The radius R8 of the fourth gradient layer is 58.1–59.2 μm;

[0035] The radius R9 of the outer cladding layer is 125 μm.

[0036] In some embodiments, the optical fiber has an attenuation coefficient of less than or equal to 0.25 dB / km at a wavelength of 1310 nm.

[0037] In some embodiments, the optical fiber has an attenuation coefficient of less than or equal to 0.16 dB / km at a wavelength of 1550 nm; a mode field diameter of 12.0 μm to 12.4 μm at a wavelength of 1550 nm; and an effective area of ​​120 to 145 μm at a wavelength of 1550 nm. 2 .

[0038] In some embodiments, the optical fiber's cutoff wavelength is less than or equal to 1520 nm.

[0039] In some embodiments, the optical fiber has a bending-added loss of less than or equal to 0.02 dB when wound 100 times around a bending radius of 30 mm at a wavelength of 1550 nm.

[0040] In some embodiments, the optical fiber has a bending-induced loss of less than or equal to 0.03 dB when wound 100 times around a bending radius of 30 mm at a wavelength of 1625 nm.

[0041] The beneficial effects of the technical solution provided in this application include:

[0042] This application provides an ultra-low loss optical fiber with a large effective area. In this application, the core layer is not doped with germanium. Gradient layers are added between the core layer and the cladding, and between adjacent cladding layers, so that the refractive index of both layers changes slowly at a certain slope, optimizing the viscosity matching at the core-cladding interface and reducing fiber attenuation caused by viscosity mismatch in the fiber structure. Simultaneously, to address the bending loss problem, this application dops each gradient layer and all cladding layers except the cladding with fluorine and boron. This results in a lower refractive index value in the recessed cladding, avoiding the situation where the refractive index difference between the core layer and the recessed cladding decreases after the core layer is not doped with germanium, thus preventing increased fiber bending loss. It is evident that compared to doping with fluorine or boron alone, co-doping with fluorine and boron results in a higher reduction in refractive index, allowing for the fabrication of a recessed layer with a lower refractive index. This results in a sufficiently small cable cutoff wavelength for the optical fiber, and the increased relative refractive index difference between the core and cladding effectively suppresses the degradation of the fiber's bending performance.

[0043] Furthermore, without adding germanium, the core layer is co-doped with boron chlorine or fluorine chlorine, and combined with graded layers and claddings co-doped with fluorine and boron chlorine to optimize the viscosity and stress of various parts of the optical fiber, thereby achieving ultra-low attenuation performance of single-mode optical fiber. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A schematic diagram of the cross-section of an ultra-low loss optical fiber with a large effective area provided in an embodiment of this application;

[0046] Figure 2 A refractive index profile of an ultra-low loss optical fiber with a large effective area provided in an embodiment of this application.

[0047] In the figure: 1. Core layer; 2. First gradient layer; 3. Inner cladding; 4. Second gradient layer; 5. Depressed cladding; 6. Third gradient layer; 7. Transition cladding; 8. Fourth gradient layer; 9. Outer cladding. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0049] See Figure 1 As shown in the figure, this application provides an ultra-low loss optical fiber with a large effective area, which includes a core layer 1, a first graded layer 2, an inner cladding 3, a second graded layer 4, a recessed cladding 5, a third graded layer 6, a transition cladding 7, a fourth graded layer 8, and an outer cladding 9 arranged sequentially from the inside to the outside along the radial direction of the optical fiber; wherein, the core layer 1 is silicon dioxide co-doped with boron chlorine or co-doped with fluorine chlorine, and is not doped with germanium; the first graded layer 2, the inner cladding 3, the second graded layer 4, the recessed cladding 5, the third graded layer 6, the transition cladding 7, and the fourth graded layer 8 are all silicon dioxide co-doped with boron fluorine; and the outer cladding 9 is pure silicon dioxide.

[0050] The principle behind this application is as follows:

[0051] Typically, to reduce optical fiber attenuation, the doping level of Ge in the core layer is reduced, or Ge is left undoped altogether. When fabricating germanium-free optical fiber preforms, a large amount of fluorine is usually added to the cladding to lower its refractive index, creating a recessed cladding refractive index profile. However, since germanium can increase the core layer's refractive index, keeping the refractive index difference between the core and the recessed cladding within a certain range, removing germanium lowers the core layer's refractive index and the refractive index difference between the core and the recessed cladding, thus increasing the fiber's bending loss to some extent. Therefore, while removing germanium reduces optical fiber attenuation, it also increases bending loss to some degree.

[0052] Therefore, in order to reduce fiber attenuation while avoiding increased bending loss, this application does not dope the core layer with germanium. Instead, graded layers are added between the core and cladding layers, and between adjacent cladding layers, so that the refractive index of both layers changes slowly at a certain slope. This optimizes the viscosity matching at the core-cladding interface and reduces fiber attenuation caused by viscosity mismatch in the fiber structure. Simultaneously, to address the bending loss problem, this application dopes each graded layer and all cladding layers except the cladding layer with fluorine and boron. This results in a lower refractive index value in the recessed cladding, avoiding the situation where the refractive index difference between the core layer and the recessed cladding decreases after the core layer is not doped with germanium, thus preventing increased bending loss. It is evident that compared to fluorine or boron doping alone, fluorine-boron co-doping results in a higher reduction in refractive index, allowing for the fabrication of recessed layers with lower refractive indices. This results in a sufficiently small cable cutoff wavelength for the fiber, and the increased relative refractive index difference between the core and cladding effectively suppresses the degradation of fiber bending performance.

[0053] Furthermore, without adding germanium, the core layer is co-doped with boron chlorine or fluorine chlorine, and combined with graded layers and claddings co-doped with fluorine and boron chlorine to optimize the viscosity and stress of various parts of the optical fiber, thereby achieving ultra-low attenuation performance of single-mode optical fiber.

[0054] In summary, in this application, the core layer 1 is not germanium-doped, but is simultaneously co-doped with chlorofluorine or chloroboron to reduce the attenuation caused by Rayleigh scattering. At the same time, adjusting the refractive index of the inner cladding and the matching depressed cladding outside the inner cladding can achieve the confinement of the light transmitted in the core layer.

[0055] Fluorine and boron co-doping of each gradient layer can significantly reduce or eliminate stress caused by the imbalance of physical properties between adjacent layers.

[0056] The inner cladding 3 is co-doped with fluorine and boron, which can control the distance between the core layer 1 and the sunken cladding 5.

[0057] The 5-layer cladding is co-doped with fluorine and boron. As the refractive index of the core layer decreases, the fiber mode field diameter (MFD) decreases accordingly. The deeper cladding layer can improve the light confinement ability within the core layer and increase the cutoff wavelength λc, which to some extent helps to alleviate optical power leakage.

[0058] The transition cladding 7 is co-doped with fluorine and boron, which allows for effective control of the fiber λc, and increases with the width / depth of the transition cladding 7, resulting in a significant improvement in macrobending performance.

[0059] The outer cladding layer 9 is designed with pure silicon dioxide, which reduces the proportion of fluorine-boron doped glass and thus reduces the manufacturing cost of optical fiber.

[0060] Furthermore, in this application, the contribution of chlorine to the relative refractive index difference ΔCl in the core layer 1 is 0.10% to 0.20%, and the contribution of boron or fluorine to the relative refractive index difference ΔB or ΔF in the core layer 1 is -0.1% to -0.05%.

[0061] In this application, the relative refractive index difference Δi is calculated using the following formula:

[0062] Δi = (n-n9) / n9 * 100%

[0063] Where n9 is the refractive index of the outer layer 9 of pure silicon dioxide. For this application, when calculating the relative refractive index difference Δ1 between the core layer 1 and pure silicon dioxide, n is the refractive index of the core layer 1 in the formula; when calculating the relative refractive index difference Δ2 between the first gradient layer 2 and pure silicon dioxide, n is the refractive index of the first gradient layer 2 in the formula; and so on for other layers.

[0064] Furthermore, in this application, the relative refractive index difference Δ1 of the core layer 1 relative to pure silicon dioxide, the relative refractive index difference Δ3 of the inner cladding layer 3 relative to pure silicon dioxide, the relative refractive index difference Δ5 of the recessed cladding layer 5 relative to pure silicon dioxide, the relative refractive index difference Δ7 of the transition cladding layer 7 relative to pure silicon dioxide, and the relative refractive index difference Δ9 of the outer cladding layer 9 relative to pure silicon dioxide satisfy: Δ1>Δ9>Δ7>Δ3>Δ5;

[0065] Specifically, see Figure 2 As shown, the relative refractive index difference Δ1 of the core layer 1 is 0.05 to 0.20%, and the radius R1 of the core layer 1 is 5.2 to 6.2 μm;

[0066] The relative refractive index difference Δ2 of the first gradient layer 2 is between the relative refractive index difference of the core layer 1 and the inner cladding layer 3, and the radius R2 of the first gradient layer 2 is 7.6~8.6um;

[0067] The relative refractive index difference Δ3 of the inner cladding 3 is -0.25 to -0.22%, and the radius R3 of the inner cladding 3 is 12.4 to 14.4 μm;

[0068] The relative refractive index difference Δ4 of the second graded layer 4 is between the relative refractive index difference of the inner cladding layer 3 and the recessed cladding layer 5, and the radius R4 of the second graded layer 4 is 15.8~16.8um;

[0069] The relative refractive index difference Δ5 of the recessed cladding 5 is -0.45 to -0.38%, and the radius R5 of the recessed cladding 5 is 20.5 to 30.5 μm;

[0070] The relative refractive index difference Δ6 of the third graded layer 6 is between the relative refractive index difference of the sunken cladding 5 and the transition cladding 7, and the radius R6 of the third graded layer 6 is 31.3~32.3um;

[0071] The relative refractive index difference Δ7 of the transition cladding 7 is -0.15 to -0.09%, and the radius R7 of the transition cladding 7 is 46.3 to 57.3 μm;

[0072] The relative refractive index difference Δ8 of the fourth graded layer 8 is between the relative refractive index difference of the transition cladding 7 and the outer cladding 9, and the radius R8 of the fourth graded layer 8 is 58.1~59.2um;

[0073] The relative refractive index difference Δ9 of the outer cladding layer 9 is 0, and the radius R9 of the outer cladding layer 9 is 125 μm.

[0074] In this application, the attenuation coefficient of the optical fiber at a wavelength of 1310 nm is less than or equal to 0.25 dB / km.

[0075] The optical fiber has an attenuation coefficient of less than or equal to 0.16 dB / km at a wavelength of 1550 nm; a mode field diameter of 12.0 μm to 12.4 μm at a wavelength of 1550 nm; and an effective area of ​​120 to 145 μm at a wavelength of 1550 nm. 2 .

[0076] The optical fiber's cutoff wavelength is less than or equal to 1520 nm.

[0077] When the optical fiber is wound 100 times around a bending radius of 30 mm at a wavelength of 1550 nm, the bending-induced loss is less than or equal to 0.02 dB.

[0078] When the optical fiber is wound 100 times around a bending radius of 30 mm at a wavelength of 1625 nm, the bending-induced loss is less than or equal to 0.03 dB.

[0079] It is evident that the optical fiber of this application exhibits good comprehensive performance parameters such as cutoff wavelength, mode field diameter, loss coefficient, and dispersion in the application band, meeting the G.654.E optical fiber standard.

[0080] Example 1:

[0081] An ultra-low loss, large effective area G.654.E optical fiber comprises, from the inside to the outside of the fiber radially, a core layer 1, a first graded layer 2, an inner cladding 3, a second graded layer 4, a recessed cladding 5, a third graded layer 6, a transition cladding 7, a fourth graded layer 8, and an outer cladding 9; wherein, the core layer 1 is chlorofluorine co-doped silicon dioxide and is not doped with germanium; the first graded layer 2, the inner cladding 3, the second graded layer 4, the recessed cladding 5, the third graded layer 6, the transition cladding 7, and the fourth graded layer 8 are all fluorine and boron co-doped silicon dioxide; and the outer cladding 9 is pure silicon dioxide.

[0082] The relative refractive index difference Δ1 of the core layer 1 is 0.10%, and the radius R1 of the core layer 1 is 5.4 μm;

[0083] The relative refractive index difference Δ2 of the first gradient layer 2 is between the relative refractive index difference between the core layer 1 and the inner cladding layer 3, and the radius R2 of the first gradient layer 2 is 8.1 μm;

[0084] The relative refractive index difference Δ3 of the inner cladding 3 is -0.23%, and the radius R3 of the inner cladding 3 is 13.4 μm;

[0085] The relative refractive index difference Δ4 of the second gradient layer 4 is between the relative refractive index difference of the inner cladding layer 3 and the recessed cladding layer 5, and the radius R4 of the second gradient layer 4 is 16.5 μm.

[0086] The relative refractive index difference Δ5 of the recessed cladding 5 is -0.42%, and the radius R5 of the recessed cladding 5 is 25.5 μm;

[0087] The relative refractive index difference Δ6 of the third graded layer 6 is between the relative refractive index difference of the sunken cladding 5 and the transition cladding 7, and the radius R6 of the third graded layer 6 is 31.7 μm.

[0088] The relative refractive index difference Δ7 of the transition cladding 7 is -0.13%, and the radius R7 of the transition cladding 7 is 52.3 μm;

[0089] The relative refractive index difference Δ8 of the fourth graded layer 8 is between the relative refractive index difference of the transition cladding 7 and the outer cladding 9, and the radius R8 of the fourth graded layer 8 is 58.5 μm.

[0090] The relative refractive index difference Δ9 of the outer cladding layer 9 is 0, and the radius R9 of the outer cladding layer 9 is 125 μm.

[0091] The optical fiber described above is prepared according to the following steps:

[0092] The deposition sequence of each layer of the optical fiber preform is from the inside out.

[0093] A chlorofluorine co-doped core layer quartz rod was prepared using the VAD process. First, a silica powder rod with a uniform outer diameter was deposited on a target rod. Then, the silica powder rod was subjected to high-temperature sintering. During the high-temperature sintering process, a fluorine source was introduced, followed by purification using helium and chlorine gas at a temperature range of 1200–1300℃. After purification, the fluorine source was continued to be introduced, and then the chlorofluorine co-doped core layer glass was sintered at 1500℃. Finally, the chlorofluorine co-doped core layer glass was stretched at high temperature to the target size to obtain the core layer quartz rod.

[0094] Fluorine-borosilicate-doped quartz tubes were prepared using the MCVD process. Fluorine-borosilicate was introduced into the quartz tube by an oxygen-rich carrier gas for fluorine-borosilicate doping. The refractive index depth of the fluorine-borosilicate doping reached at least below -0.0075 absolute refractive index (-0.510% relative refractive index), and the refractive index range / average value of the entire rod was controlled within 1.2%.

[0095] The core quartz rod is assembled into a boron-doped quartz sleeve using the RIT process. The interface between the core quartz rod and the boron-doped quartz sleeve is purified by high temperature, and then fused together by vacuum.

[0096] Finally, the outer coating powder portion was prepared using the OVD process to obtain the preform.

[0097] The inner cladding, gradient layer, recessed cladding, and transition cladding in the boron-doped quartz sleeve are prepared using one or a combination of VAD (axial vapor deposition), MCVD (chemical vapor deposition), PCVD (plasma chemical vapor deposition), and OVD (external vapor deposition).

[0098] Finally, the prepared preform is drawn into an optical fiber from the top of the drawing furnace. The preform is then gradually cooled in an annealing furnace with a temperature gradient of 900-1000℃ to release the internal stress. After coating and curing, the optical fiber is then screened to complete the processing and obtain the finished optical fiber.

[0099] The optical fibers prepared above were subjected to performance tests in different wavelength bands, including attenuation performance, dispersion slope, mode field diameter, cutoff wavelength, and effective area. The test results are shown in Table 1 below.

[0100] Table 1

[0101]

[0102] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0103] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0104] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An ultra-low loss optical fiber with a large effective area, characterized in that, It includes a core layer (1), a first graded layer (2), an inner cladding layer (3), a second graded layer (4), a sunken cladding layer (5), a third graded layer (6), a transition cladding layer (7), a fourth graded layer (8), and an outer cladding layer (9) arranged sequentially from the inside to the outside along the radial direction of the optical fiber. The core layer (1) is silicon dioxide co-doped with boron chlorine or co-doped with fluorine chlorine, and is not doped with germanium; The first gradient layer (2), inner cladding layer (3), second gradient layer (4), sunken cladding layer (5), third gradient layer (6), transition cladding layer (7) and fourth gradient layer (8) are all fluorine-boron co-doped silicon dioxide; The outer cladding layer (9) is pure silicon dioxide; The relative refractive index difference Δ1 of the core layer (1) relative to pure silicon dioxide, the relative refractive index difference Δ3 of the inner cladding layer (3) relative to pure silicon dioxide, the relative refractive index difference Δ5 of the sunken cladding layer (5) relative to pure silicon dioxide, the relative refractive index difference Δ7 of the transition cladding layer (7) relative to pure silicon dioxide, and the relative refractive index difference Δ9 of the outer cladding layer (9) relative to pure silicon dioxide satisfy the following: Δ1 > Δ9 > Δ7 > Δ3 > Δ5.

2. The ultra-low loss, large effective area optical fiber as described in claim 1, characterized in that: The contribution of chlorine to the relative refractive index difference ΔCl in the core layer (1) is 0.10% to 0.20%, and the contribution of boron or fluorine to the relative refractive index difference ΔB or ΔF in the core layer (1) is -0.1% to -0.05%.

3. The ultra-low loss, large effective area optical fiber as described in claim 1, characterized in that: The relative refractive index difference Δ1 of the core layer (1) is 0.05 to 0.20%; The relative refractive index difference Δ2 of the first gradient layer (2) is between the relative refractive index difference between the core layer (1) and the inner cladding layer (3); The relative refractive index difference Δ3 of the inner cladding (3) is -0.25 to -0.22%; The relative refractive index difference Δ4 of the second gradient layer (4) is between the relative refractive index difference of the inner cladding (3) and the sunken cladding (5); The relative refractive index difference Δ5 of the sunken cladding (5) is -0.45 to -0.38%; The relative refractive index difference Δ6 of the third gradient layer (6) is between the relative refractive index difference of the sunken cladding (5) and the transition cladding (7); The relative refractive index difference Δ7 of the transition cladding (7) is -0.15 to -0.09%; The relative refractive index difference Δ8 of the fourth gradient layer (8) is between the relative refractive index difference of the transition cladding (7) and the outer cladding (9); The relative refractive index difference Δ9 of the outer cladding layer (9) is 0.

4. The ultra-low loss, large effective area optical fiber as described in claim 1, characterized in that: The radius R1 of the core layer (1) is 5.2 to 6.2 μm; The radius R2 of the first gradient layer (2) is 7.6~8.6 μm; The radius R3 of the inner cladding (3) is 12.4~14.4 μm; The radius R4 of the second gradient layer (4) is 15.8~16.8 μm; The radius R5 of the sunken cladding (5) is 20.5~30.5um; The radius R6 of the third gradient layer (6) is 31.3~32.3um; The radius R7 of the transition cladding (7) is 46.3~57.3 μm; The radius R8 of the fourth gradient layer (8) is 58.1~59.2um; The radius R9 of the outer cladding layer (9) is 125 μm.

5. The ultra-low loss, large effective area optical fiber as described in claim 1, characterized in that: The optical fiber has an attenuation coefficient of less than or equal to 0.25 dB / km at a wavelength of 1310 nm.

6. The ultra-low loss, large effective area optical fiber as described in claim 1, characterized in that: The optical fiber has an attenuation coefficient of less than or equal to 0.16 dB / km at a wavelength of 1550 nm; a mode field diameter of 12.0 μm to 12.4 μm at a wavelength of 1550 nm; and an effective area of ​​120 to 145 μm at a wavelength of 1550 nm. 2 .

7. The ultra-low loss, large effective area optical fiber as described in claim 1, characterized in that: The optical fiber's cutoff wavelength is less than or equal to 1520 nm.

8. The ultra-low loss, large effective area optical fiber as described in claim 1, characterized in that: When the optical fiber is wound 100 times around a bending radius of 30 mm at a wavelength of 1550 nm, the bending-induced loss is less than or equal to 0.02 dB.

9. The ultra-low loss, large effective area optical fiber as described in claim 1, characterized in that: When the optical fiber is wound 100 times around a bending radius of 30 mm at a wavelength of 1625 nm, the bending-induced loss is less than or equal to 0.03 dB.

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