Low-attenuation non-zero dispersion shift single-mode fiber and application

Abstract

The invention relates to a low-attenuation non-zero dispersion shift single-mode fiber and application, the low-attenuation non-zero dispersion shift single-mode fiber comprises a first core layer, a second core layer, a third core layer, a sunken cladding, an auxiliary cladding and a first outer cladding, the radius R1 of the first core layer is 0.8-1.3 [mu] m, the relative refractive index difference 1 is-0.01%-0.05%, the radius R2 of the second core layer is 1.5-1.8 [mu] m, the relative refractive index difference 2 is-0.12%-0.15%, the radius R3 of the third core layer is 2.0-2.5 [mu] m, and the radius R2 of the third core layer is 0.5-1.5 [mu] m. The radius R4 of the sunken cladding layer is 5-6.5 microns, the relative refractive index difference 3 is-0.34% to-0.30%, the radius R4 of the sunken cladding layer is 5-6.5 microns, and the relative refractive index difference delta 4 is-0.51% to-0.57%. The core layer of the optical fiber is of a three-core-layer structure, the interlayer stress is reduced when the optical fiber is drawn, and the relative refractive index difference of the core layer is close to 0, so that the distortion of the core layer can be reduced, and the attenuation of the optical fiber is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical communications, and in particular relates to a low-attenuation non-zero dispersion-shifted single-mode optical fiber and its application. Background Art

[0002] With the rapid global deployment of 5G, optical communication networks are evolving toward longer distances, higher capacity, and higher speeds. As communication networks move toward next-generation systems, fiber optic infrastructure with high transmission capacity is fundamental. Optical communications, characterized by high transmission capacity, long distances, and high speeds, are widely used in optical communication systems such as long-distance trunk lines, metropolitan area networks, and access networks. Optical fiber that meets ITU-TG.655, commonly referred to as non-zero dispersion-shifted fiber, is designed to optimize dense wavelength division multiplexing systems. G.655 fiber is also an excellent choice for high-capacity, longer-distance metropolitan core or regional aggregation links, particularly where DWDM is deployed. It is also widely used in submarine cable systems and the core layer of metropolitan area networks.

[0003] The attenuation coefficient of optical fiber is one of its most important performance indicators, largely determining the distance between relay stations in optical fiber communications. In long-distance optical fiber transmission, the smaller the fiber's attenuation coefficient, the greater the distance it can transmit optical signals, reducing the operating costs of optical communications. Therefore, reducing optical power loss and minimizing the impact of fiber nonlinear effects have become the development direction of optical fiber communications.

[0004] The main component of communication optical fiber is high-purity SiO2. The optical fiber is drawn from an optical fiber preform rod. The internal structure of the optical fiber preform rod is divided into a core layer and a cladding layer. The refractive index of the core layer is larger, and the refractive index of the cladding is smaller. Light is mainly transmitted in the optical fiber core layer. Germanium is usually doped into the core layer to increase the refractive index of the glass, and fluorine is usually doped into the cladding to reduce the refractive index, so as to obtain a suitable refractive index difference and thus obtain the required optical communication performance.

[0005] Currently, non-zero dispersion-shifted single-mode optical fiber is widely used in communication networks. The attenuation of optical fiber is rarely mentioned in patent applications of this type. The 1550 attenuation of the current mainstream non-zero dispersion-shifted single-mode optical fiber is generally 0.190-0.210dB / km, which is relatively high.

[0006] Patent CN1068434C is still the design basis for the mainstream G.655 optical fiber. This product has a high attenuation value, att1550 is 0.195-0.21dB / km.

[0007] Patent CN119758515A uses a gradient core layer to increase the mode field diameter and reduce attenuation to 0.180-0.185dB / km. However, the attenuation of this product is not low enough and does not reach within 0.180 dB / km.

[0008] Therefore, it is necessary to design a low-attenuation non-zero dispersion-shifted single-mode optical fiber. Summary of the Invention

[0009] The following are definitions and explanations of some terms involved in this invention: Starting from the axis of the optical fiber core, according to the change of refractive index, the layer closest to the axis is defined as the core layer, and the second outer cladding of the optical fiber, that is, the pure silica layer, is defined as the optical fiber.

[0010] The relative refractive index difference △i of each layer of optical fiber is defined by the following equation, △i =(n i -n c )*100% / n c in is the refractive index of the specified layer, and is the refractive index of pure silicon dioxide.

[0011] Relative refractive index contribution of Ge doping in the fiber core It is defined by the following equation, ; in is the change in the refractive index of silica glass caused by the Ge dopant in the core when it is doped into pure silica without other dopants, and is the refractive index of the first outer cladding, i.e., the refractive index of pure silica. The relative refractive index contribution of fluorine doping has the same meaning. The ratio of the mass of doped phosphorus to the mass of the glass is the phosphorus ratio, denoted as np (in wt%).

[0012] The technical problem to be solved by the present invention is to propose a low-loss non-zero dispersion-shifted single-mode optical fiber and its application in response to the deficiencies in the above-mentioned prior art.

[0013] The technical solutions adopted in the present invention are as follows: A low-attenuation non-zero dispersion-shifted single-mode optical fiber comprises a core layer and a cladding surrounding the core layer, characterized in that: the core layer comprises, from the inside out, a first core layer, a second core layer, and a third core layer; the cladding comprises, from the inside out, a depressed cladding, an auxiliary cladding, and a first outer cladding, the second outer cladding being a pure silica glass layer; the first core layer radius R1 is 0.8 to 1.3 μm, and the relative refractive index difference Δ1 is -0.01% to 0.05%; the second core layer radius R2 is 1.5 to 1.8 μm, and the relative refractive index difference Δ2 is -0.12% to 0.15%; the third core layer radius R3 is 2.0 to 2.5 μm, and the relative refractive index difference Δ3 is -0.34% ~-0.30%, the depressed cladding radius R4 is 5~6.5μm, the relative refractive index difference Δ4 is ​​-0.51%~-0.57%, the auxiliary cladding radius R5 is 9~11μm, the relative refractive index difference △5 is -0.30%~-0.36%, the first outer cladding radius R6 is 15~18μm, △6 is -0.42%~-0.50%, and the second outer cladding is a pure silica glass layer.

[0014] According to the above technical solution, the ratio of the radii of the third core layer, the second core layer and the first core layer R3:R2:R1 is 2.7-3.2:1.9-2.3:1.

[0015] According to the above technical solution, the relative refractive index difference Δ1 of the first core layer is -0.01~0.05%, and the relative refractive index contribution of fluorine doping in the first core layer is -0.03~-0.05wt%.

[0016] According to the above technical solution, the relative refractive index difference Δ2 of the second core layer is -0.12%~0.15%, and the relative refractive index contribution of germanium doped in the second core layer is 0.02-0.06wt%.

[0017] According to the above technical solution, the relative refractive index difference Δ3 of the third core layer is -0.34% to -0.30%, and the relative refractive index contribution of germanium doped in the third core layer is 0.03-0.08wt%.

[0018] According to the above technical solution, the depressed cladding, auxiliary cladding and first outer cladding are all pure fluorine-doped layers and do not contain germanium.

[0019] According to the above technical solution, the second outer cladding layer is a pure silica glass layer, △7≈0, r7=62.5μm.

[0020] According to the above technical solution, the first core layer is doped with phosphorus, and the corresponding optical fiber preform is prepared by the PCVD process. The phosphorus is introduced by the carrier gas when the core layer is deposited by the PCVD process; the three core layers are doped with different concentrations of phosphorus, the phosphorus doping concentration of the first core layer is 0.05-0.1%, the phosphorus doping concentration of the second core layer is 0.01-0.05%, and the phosphorus doping concentration of the third core layer is 0.005%-0.01%.

[0021] According to the above technical solution, the first core layer, the second core layer and the third core layer are gradiently doped with phosphorus, with the first core layer having the highest phosphorus doping concentration and the second and third core layers having decreasing phosphorus doping concentrations.

[0022] According to the above technical solution, the cabling cutoff wavelength of the optical fiber is equal to or less than 1450 nm.

[0023] According to the above technical solution, the dispersion of the optical fiber at a wavelength of 1550nm is equal to or less than 6.0 ps / nm*km and equal to or greater than 2.0 ps / nm*km, and the dispersion slope of the optical fiber at a wavelength of 1550nm is less than 0.084ps / nm2*km.

[0024] According to the above technical solution, the attenuation of the optical fiber at a wavelength of 1550 nm is equal to or less than 0.180 dB / km; under preferred conditions, it is equal to or less than 0.178 dB / km.

[0025] According to the above technical solution, the attenuation of the optical fiber at a wavelength of 1625 nm is equal to or less than 0.2 dB / km; under preferred conditions, it is equal to or less than 0.195 dB / km.

[0026] The invention discloses an application of a low-attenuation non-zero dispersion-shifted single-mode optical fiber, wherein the optical fiber is applied in the fields of laser, communication or sensing.

[0027] The beneficial effects of the present invention are: 1. The optical fiber core layer is a three-core layer structure, which reduces the interlayer stress during optical fiber drawing and makes the relative refractive index difference of the core layer close to 0, which can reduce the core layer distortion and the Rayleigh scattering coefficient of the optical fiber, thereby reducing the attenuation of the optical fiber.

[0028] 2. The optical fiber adopts the design of depressed cladding and auxiliary cladding to ensure that the optical fiber has a suitable cable cutoff wavelength.

[0029] 3. The relative refractive index difference from the core layer to the inner cladding decreases step by step from the inside to the outside, reducing mutations, which is conducive to a reasonable transition of viscosity at the interface, reducing optical fiber stress, improving optical fiber performance, and reducing attenuation.

[0030] 4. The addition of phosphorus doping to the core layer can soften the silica glass network to optimize the core layer viscosity. With the help of reasonable design of the core cladding structure, the Rayleigh scattering coefficient of the optical fiber can be reduced, and the attenuation can be further reduced.

[0031] 5. The gradient phosphorus doping of the first, second, and third core layers is intended to reduce interlayer stress among the three core layers. This is lower than the interlayer stress of layers doped with phosphorus at the same concentration. At the same time, it ensures that the phosphorus doping in the innermost core layer is the highest. In the first core layer where the optical power is most concentrated, Rayleigh scattering and attenuation are reduced. Therefore, the gradient phosphorus doping design is conducive to reducing optical fiber attenuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 This is a refractive index cross-sectional structure diagram of the first embodiment of the present invention. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0035] like Figure 1As shown, this embodiment provides a low-attenuation non-zero dispersion-shifted single-mode optical fiber, comprising a core layer and a cladding surrounding the core layer, wherein the core layer is sequentially composed of a first core layer, a second core layer, and a third core layer from the inside out; the cladding is sequentially composed of a depressed cladding, an auxiliary cladding, and a first outer cladding from the inside out, the second outer cladding is a pure silica glass layer, the first core layer radius R1 is 0.8-1.3 μm, and the relative refractive index difference Δ1 is -0.01%-0.05%, the second core layer radius R2 is 1.5-1.8 μm, and the relative refractive index difference Δ2 is -0.12%-0.15%, the third core layer radius R3 is 2.0-2.5 μm, and the relative refractive index difference Δ3 is -0.34%. The depressed cladding radius R4 is 5 to 6.5 μm, with a relative refractive index difference Δ4 of -0.51% to -0.57%. The auxiliary cladding radius R5 is 9 to 11 μm, with a relative refractive index difference Δ5 of -0.30% to -0.36%. The first outer cladding radius R6 is 15 to 18 μm, with a Δ6 of -0.42% to -0.50%. The second outer cladding is a pure silica glass layer with a Δ7 of 0. The optical fiber core of the present invention has a three-core structure, which reduces interlayer stress during optical fiber drawing. Combined with the core relative refractive index difference being close to 0, core distortion can be reduced, thereby lowering optical fiber attenuation.

[0036] The ratio of the radius of the third core layer, the second core layer and the first core layer R3:R2:R1 is 2.7-3.2:1.9-2.3:1. Preferably, R3:R2:R1≈3:2:1.

[0037] The relative refractive index difference Δ1 of the first core layer is -0.01 to 0.05%, and the relative refractive index contribution of fluorine doping in the first core layer is -0.03 to -0.05%, preferably -0.035% to 0.045%.

[0038] The relative refractive index difference Δ2 of the second core layer is -0.12% to 0.15%, and the relative refractive index contribution of germanium doped in the second core layer is 0.02-0.06wt%, preferably 0.03-0.05wt%.

[0039] The relative refractive index difference Δ3 of the third core layer is -0.34% to -0.30%, and the relative refractive index contribution of germanium doped in the third core layer is 0.03-0.08wt%, preferably 0.04-0.07wt%.

[0040] The sunken cladding, auxiliary cladding and first outer cladding are all pure fluorine-doped layers and do not contain germanium.

[0041] The second outer cladding layer is a pure silica glass layer, Δ7≈0, r7=62.5 μm.

[0042] The first core layer is doped with phosphorus. The corresponding optical fiber preform is prepared using a PCVD process. The phosphorus is introduced by the carrier gas during core layer deposition using the PCVD process. The three core layers are doped with different concentrations of phosphorus: 0.05-0.1% for the first core layer, 0.01-0.05% for the second core layer, and 0.005%-0.01% for the third core layer. Phosphorus doping can appropriately increase the delta value of the core layer and effectively reduce the attenuation of the optical fiber.

[0043] Since light transmission is mainly in the core layer, phosphorus doping can soften the silica glass network, reduce Rayleigh scattering, and thus reduce optical fiber attenuation. The first core layer, the second core layer, and the third core layer are gradient-doped with phosphorus. The phosphorus doping concentration of the first core layer is the highest, and the phosphorus doping concentrations of the second and third core layers decrease in sequence. For example, the first core layer has np=0.05wt%, the second core layer has np=0.03wt%, and the third core layer has np=0.008wt%. The purpose of gradient phosphorus doping is to reduce the interlayer stress of the three core layers, which is smaller than the interlayer stress of phosphorus doping with the same concentration. At the same time, it ensures that the phosphorus doping amount of the innermost first core layer is the largest, reducing Rayleigh scattering and attenuation in the first core layer where the optical power is most concentrated. Therefore, the design of gradient phosphorus doping is conducive to reducing optical fiber attenuation.

[0044] This embodiment also provides an application of a low-attenuation non-zero dispersion-shifted single-mode optical fiber, which is used in the fields of laser, communication, or sensing.

[0045] Tables 1 and 2 provide parameter descriptions for specific embodiments 1 to 11. As can be seen from Tables 1 and 2, the cabled cutoff wavelength of the optical fiber is equal to or less than 1450 nm. The dispersion of the optical fiber at a wavelength of 1550 nm is equal to or less than 6.0 ps / nm*km and equal to or greater than 2.0 ps / nm*km. The dispersion slope of the optical fiber at a wavelength of 1550 nm is less than 0.084 ps / nm2*km. Preferably, the dispersion slope is 0.075 ps / nm2*km. The attenuation of the optical fiber at a wavelength of 1550 nm is equal to or less than 0.180 dB / km; preferably, it is equal to or less than 0.178 dB / km. The attenuation of the optical fiber at a wavelength of 1625 nm is equal to or less than 0.2 dB / km; preferably, it is equal to or less than 0.195 dB / km.

[0046] Table 1

[0047] Table 2

[0048] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A low-attenuation non-zero dispersion-shifted single-mode optical fiber comprising a core layer and a cladding surrounding the core layer, characterized in that: The core layers are sequentially the first core layer, the second core layer and the third core layer from the inside to the outside; the cladding layers are sequentially the sunken cladding, the auxiliary cladding, the first outer cladding and the second outer cladding from the inside to the outside. The radius R1 of the first core layer is 0.8~1.3μm, and the relative refractive index difference △1 is -0.01%~0.05%. The radius R2 of the second core layer is 1.5~1.8μm, and the relative refractive index difference △2 is -0.12%~0.15%. The radius R3 of the third core layer is 2.0~2.5μm, and the relative refractive index difference △3 is -0.34%~-0.30%. The radius R4 of the sunken cladding is 5~6.5μm, and the relative refractive index difference Δ4 is ​​-0.51%~-0.57%. The radius R5 of the auxiliary cladding is 9~11μm, and the relative refractive index difference △5 is -0.30%. ~-0.36%, the radius R6 of the first outer cladding is 15~18μm, △6 is -0.42% ~-0.50%, and the second outer cladding is a pure silica glass layer.

2. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1, characterized in that: The ratio of the radii of the third core layer, the second core layer and the first core layer, R3:R2:R1, is 2.7-3.2:1.9-2.3:

1.

3. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The relative refractive index difference Δ1 of the first core layer is -0.01 to 0.05%, and the relative refractive index contribution of fluorine doping in the first core layer is -0.03 to -0.05%.

4. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The relative refractive index difference Δ2 of the second core layer is -0.12% to 0.15%, and the relative refractive index contribution of germanium doped in the second core layer is 0.02-0.06%.

5. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The relative refractive index difference Δ3 of the third core layer is -0.34% to -0.30%, and the relative refractive index contribution of germanium doped in the third core layer is 0.03-0.08%.

6. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The sunken cladding, auxiliary cladding and first outer cladding are all pure fluorine-doped layers.

7. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The second outer cladding layer is a pure silica glass layer, with Δ7≈0 and R7=62.5 μm.

8. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The first core layer is doped with phosphorus, and the corresponding optical fiber preform is prepared by the PCVD process. The phosphorus is introduced by the carrier gas when the core layer is deposited by the PCVD process; the three core layers are doped with different concentrations of phosphorus, the phosphorus doping concentration of the first core layer is 0.05-0.1wt%, the phosphorus doping concentration of the second core layer is 0.01-0.05wt%, and the phosphorus doping concentration of the third core layer is 0.005%-0.01wt%.

9. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 8, characterized in that: The first core layer, the second core layer and the third core layer are gradiently doped with phosphorus, wherein the phosphorus doping concentration of the first core layer is the highest, and the phosphorus doping concentrations of the second core layer and the third core layer decrease in sequence.

10. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The cabled cutoff wavelength of the optical fiber is equal to or less than 1450 nm.

11. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The dispersion of the optical fiber at a wavelength of 1550 nm is equal to or less than 6.0 ps / nm*km and equal to or greater than 2.0 ps / nm*km, and the dispersion slope of the optical fiber at a wavelength of 1550 nm is less than 0.084 ps / nm 2 *km,.

12. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The attenuation of the optical fiber at a wavelength of 1550 nm is equal to or less than 0.180 dB / km; preferably, it is equal to or less than 0.178 dB / km.

13. The low-attenuation non-zero dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The attenuation of the optical fiber at a wavelength of 1625 nm is equal to or less than 0.2 dB / km; preferably, it is equal to or less than 0.195 dB / km.

14. Use of a low-attenuation non-zero dispersion-shifted single-mode optical fiber according to any one of claims 1 to 13, characterized in that: The optical fiber is used in the fields of laser, communication or sensing.

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