Non-zero dispersion-shifted single-mode optical fiber with short cutoff wavelength and low macrobending loss and application thereof

Abstract

The application relates to a non-zero dispersion-shifted single-mode optical fiber with a low cutoff wavelength and a low macro-bending loss and an application, which comprises a core layer and a cladding layer surrounding the core layer, the cladding layer comprises a depression layer, an inner cladding layer and an outer cladding layer arranged in sequence from inside to outside, the inner cladding layer comprises a first inner cladding layer and a second inner cladding layer arranged in sequence from inside to outside, the relative refractive index difference Delta 1 of the core layer is 0.500% to 0.570%, and the refractive index curve of the core layer is a gradually decreasing parabolic shape, and the refractive index decreases with the increase of the core diameter. The shape of the refractive index profile of the optical fiber is adjusted, the conventional multi-core layer step type design is avoided, the gradually decreasing parabolic design is adopted, compared with the triangular depression core structure, the core center high refractive index range and the effective refractive index area of the application are larger, the waveguide of the light can be effectively bound in the core, and compared with the trapezoidal core, the core layer decreases in a parabolic mode with the radius, the radius of the core layer can be effectively reduced, and the purposes of reducing the cutoff wavelength and the bending loss are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical communication, and particularly relates to a short cutoff wavelength low macro-bending loss non-zero dispersion shift single-mode optical fiber and application. BACKGROUND

[0002] With the promotion of the strategy of "network power", China is accelerating the extension of communication networks to complex terrain areas such as remote mountainous areas, plateaus and deserts. The terrain in these areas is rugged, and the laying environment is complex. In mountainous areas, overhead laying needs to frequently bypass obstacles, and direct-buried laying faces rock extrusion. The optical cable is required to maintain low loss under the bending radius to avoid signal attenuation caused by repeated bending. Although the new generation of optical fiber G.657 surpasses G.655 in terms of bending resistance, it is suitable for short-distance access. At the same time, although the ultra-low-loss optical fiber (G.654E) supports ultra-long-distance non-repeater transmission, its anti-microbending performance is weaker than that of G.655, and its applicability is limited in rock geology direct-buried scenes. The "bending resistance + low dispersion" combination characteristics of G.655 meet the needs of long-distance relay in mountainous areas. Guangdong Mobile purchased 6.89 million core kilometers of G.655 optical cables in 2025, which are explicitly used for fault repair in mountainous areas, and need to withstand repeated bending and mechanical stress.

[0003] Chinese invention patent CN116643345A discloses a structure of a non-zero dispersion shift optical fiber with a short cutoff wavelength and a large effective area. The optical fiber is prepared by an external vapor deposition process (OVD), and the overall waveguide structure of the core layer is designed as a triangular core + ring type, and a center local recess and a base type structure are added. The center local recess structure of this invention reduces the effective refractive index area, which is beneficial to achieving a large effective area and reducing nonlinear effects, but is not conducive to the bending performance of the optical fiber. At the same time, the center local recess structure needs to increase the amount of original positive dopant such as germanium (Ge) to improve the utilization rate of doping. The increase in the amount of dopant will also increase the amount of chemical impurities. These impurities form defects that will become obstacles in optical fiber transmission, causing scattering loss, which is not conducive to attenuation control. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a short cutoff wavelength low macro-bending loss non-zero dispersion shift single-mode optical fiber and application that can reduce the cutoff wavelength and bending loss.

[0005] The technical solution adopted by the present application is as follows:

[0006] A non-zero dispersion-shifted single-mode optical fiber with a short cutoff wavelength and low macro-bending loss comprises a core layer and a cladding layer surrounding the core layer, characterized in that the cladding layer comprises, from inside to outside, a depressed layer, an inner cladding layer and an outer cladding layer, wherein the inner cladding layer comprises, from inside to outside, a first inner cladding layer and a second inner cladding layer, the relative refractive index difference Δ1 between the core layer and a pure silica glass layer is 0.500% to 0.570%, and the refractive index curve of the core layer is a gradually decreasing parabolic shape, and the refractive index decreases with the increase of the core diameter; the relative refractive index differences of the core layer, the depressed layer, the first inner cladding layer, the second inner cladding layer and the outer cladding layer satisfy the following conditions:

[0007] Δ1>Δ3>Δ5>Δ2>Δ4;

[0008] Wherein Δ1 is the relative refractive index difference of the core layer, Δ2 is the relative refractive index difference of the depressed layer, Δ3 is the relative refractive index difference of the first inner cladding layer, Δ4 is the relative refractive index difference of the second inner cladding layer, and Δ5 is the relative refractive index difference of the outer cladding layer.

[0009] According to the above technical solution, the core layer is doped with germanium, and the relative refractive index difference Δ1 between the core layer and a pure silica glass layer is 0.520% to 0.550%.

[0010] According to the above technical solution, the radius of the core layer is R1, the radius of the depressed layer is R2, R2:R1=2.5 to 3.0, the radius of the first inner cladding layer is R3, R3:R1=4.0 to 4.7, the radius of the second inner cladding layer is R4, R4:R1=4.7 to 5.3, and the radius of the outer cladding layer is R5=62.5μm.

[0011] According to the above technical solution, the radius R1 of the core layer is 2.0 to 3.0μm.

[0012] According to the above technical solution, the relative refractive index difference Δ2 between the depressed layer and a pure silica glass layer is -0.055% to -0.005%.

[0013] According to the above technical solution, the relative refractive index difference Δ3 between the first inner cladding layer and a pure silica glass layer is 0.100% to 0.200%.

[0014] According to the above technical solution, the relative refractive index difference Δ4 between the second inner cladding layer and a pure silica glass layer is -0.150% to -0.055%.

[0015] According to the above technical solution, the outer cladding layer is a pure silica glass layer, and the relative refractive index difference Δ5=0.

[0016] According to the technical scheme, the optical fiber has an attenuation of less than or equal to 0.400 dB / km at a wavelength of 1383 nm, an attenuation of less than or equal to 0.190 db / km at a wavelength of 1550 nm, and an attenuation of less than or equal to 0.204 db / km at a wavelength of 1625 nm; a mode field diameter of 9.2-9.5 mu m at 1550 nm; a cabling cutoff wavelength of less than or equal to 1250 nm; a zero dispersion wavelength of 1322-1520 nm; a dispersion of 2.0-5.5 ps / nm*km at 1530-1565 nm; a dispersion of 4.5-10.2 ps / nm*km at 1575-1625 nm; and a zero dispersion slope of less than or equal to 0.075 ps / nm*km. 2 The bending additional loss of the optical fiber is less than 0.015 dB at wavelengths of 1550 nm, 1580 nm and 1625 nm after the optical fiber is wound 100 times at a diameter of 60 mm.

[0017] The application of the short cutoff wavelength low macro-bending loss non-zero dispersion shift single-mode optical fiber, characterized in that the optical fiber is applied to the fields of communication, laser or sensing.

[0018] The application has the following beneficial effects:

[0019] 1. The application adjusts the shape of the refractive index profile of the optical fiber, avoids the conventional multi-core layer step type design, and adopts the design of a gradually changing parabola.

[0020] 2. The application designs the relative refractive index difference of each layer, the relative refractive index difference of the core layer is the largest in the profile design and serves as the main waveguide transmission layer, the relative refractive index difference of the sunken layer is designed as a sunken structure with a negative relative refractive index difference, which can limit the leakage of the optical signal of the core layer in the bending state, and the relative refractive index difference of the first inner cladding layer is designed as a high refractive index step structure, which mainly matches the sharp change of the refractive index of the core layer and the sunken layer structure, enhances the total reflection of light in the core layer, and effectively reduces the mode field diameter. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some embodiments of the present application, and should not be regarded as a limitation on the scope, and other related drawings can also be obtained by those skilled in the art without creative labor.

[0022] Figure 1The refractive index profile provided in the embodiments of the present application. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. 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.

[0024] As shown in the drawings, Figure 1 The present embodiment provides a short cutoff wavelength low macro-bending loss non-zero dispersion shift optical fiber, which has five glass layers with different refractive indexes in the waveguide structure design, and from inside to outside, they are a core layer, a depression layer, an inner cladding layer and an outer cladding layer in sequence, wherein the inner cladding layer comprises a first inner cladding layer and a second inner cladding layer arranged from inside to outside in sequence.

[0025] The core layer is doped with germanium (Ge), and the refractive index curve of the core layer is controlled to present a gradually decreasing parabolic shape by a PCVD process, and the refractive index gradually decreases with the increase of the core diameter. In the profile design, the relative refractive index difference of this layer is the largest and serves as the main waveguide transmission layer. The radius R1 of the core layer is 2.0-3.0 μm, and the relative refractive index difference Δ1 of the highest part of the core layer is 0.500%-0.570%, preferably 0.520%-0.550%, and the minimum relative refractive index difference of the edge of the core layer is -0.055%, i.e. the minimum value within the range of Δ2.

[0026] The depression layer is doped with fluorine (F), and this layer is designed as a depression structure with a negative relative refractive index difference, which can limit the leakage of the core layer optical signal in the bending state. The radius of the depression layer is R2, R2:R1=2.5-3.0, and the relative refractive index difference Δ2 between the depression layer and the pure silica glass layer is -0.055%-0.005%.

[0027] The first inner cladding layer is doped with germanium (Ge), and this layer is designed as a high refractive index step structure, mainly to match the sharp change of the refractive index of the core layer and the depression layer structure, to enhance the total reflection of light in the core layer, and to effectively reduce the mode field diameter. The radius of the first inner cladding layer is R3, R3:R1=4.0-4.7, and the relative refractive index difference Δ3 between the first inner cladding layer and the pure silica glass layer is 0.100%-0.200%.

[0028] The second inner cladding layer is doped with fluorine (F), and the radius of the second inner cladding layer is R4, R4:R1=4.7-5.3, and the relative refractive index difference Δ4 between the second inner cladding layer and the pure silica glass layer is -0.150%-0.055%. The outer cladding layer is a pure silica glass layer, and the radius R5 is 62.5 μm.

[0029] The relative refractive index difference of each layer satisfies:

[0030] Δ1>Δ3>Δ5>Δ2>Δ4.

[0031] Wherein, Δ1 is the relative refractive index difference of the core layer, which is the largest in the profile design and serves as the main waveguide transmission layer; Δ2 is the relative refractive index difference of the down-dip layer, which is designed as a down-dip structure with a negative relative refractive index difference, so as to limit the leakage of the core layer optical signal in the bending state. Δ3 is the relative refractive index difference of the first inner cladding layer, which is designed as a high refractive index step structure, mainly to match the refractive index of the core layer and the down-dip layer structure, enhance the total reflection of light in the core layer, and effectively reduce the mode field diameter. Δ4 is the relative refractive index difference of the second inner cladding layer, and Δ5 is the relative refractive index difference of the outer cladding layer.

[0032] The optical fiber with the profile structure disclosed above can be prepared by a plasma chemical vapor deposition (PCVD) process to obtain a fiber preform, and then by controlling the drawing speed at 1200-1500 m / min to obtain the optical fiber. The refractive index curve of the core layer in the profile structure can be obtained by the following formula:

[0033]

[0034] Wherein,

[0035]

[0036]

[0037] In the formula, Δ1 is the relative refractive index difference of the core layer, Δ2 is the relative refractive index difference of the down-dip layer, and R1 is the radius of the core layer.

[0038] As can be seen from the above formula, the actual relative refractive index difference value Δ 2 of the core layer parabolic profile decreases with the gradual increase of the radius R, and the maximum and minimum values are and , respectively, R is the independent variable, Δ is the relative refractive index corresponding to R, and f(R) is the parabolic curvature change coefficient varying with the radius R.

[0039] The following is a specific parameter comparison chart of specific embodiments 1 to 5 based on the technical scheme of the short cutoff wavelength low macro-bending loss non-zero dispersion shift optical fiber

[0040] The waveguide structure parameters of embodiments 1-5 are shown in Table 1.

[0041] Table 1

[0042]

[0043] The optical fiber preform was prepared according to the parameters designed in the above-mentioned examples 1-5, and the parameters of the drawn optical fiber are shown in Table 2.

[0044] Table 2

[0045]

[0046] As can be seen from the test results of the drawn optical fiber of each example in the above table, compared with the triangular core design, the mode field diameter of the parabolic core layer structure design of the present application is relatively reduced, and the cutoff wavelength is less than 1250 nm, and the additional value of the bending loss measured at 60 mm and 100 turns is less than 0.015 dB / km, and the attenuation coefficient at 1550 nm is also better than the test results of the optical fiber with the "triangular + ring structure with central local recess", which can be more suitable for the scenes of overhead laying in mountainous areas, network repair in complex environments and direct burial in rock geology, etc.

[0047] The above-described examples are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

Claims

1. A non-zero dispersion-shifted single-mode optical fiber having a short cutoff wavelength and low macrobending loss, comprising a core layer and a cladding layer surrounding the core layer, characterized in that: The cladding comprises a depression layer, an inner cladding layer and an outer cladding layer arranged in sequence from inside to outside, wherein the inner cladding layer comprises a first inner cladding layer and a second inner cladding layer arranged in sequence from inside to outside, the core layer has a relative refractive index difference Δ1 of 0.500% to 0.570%, and the refractive index curve of the core layer is a gradually decreasing parabolic shape, and the refractive index decreases with the increase of the core diameter; the relative refractive index differences of the core layer, the depression layer, the first inner cladding layer, the second inner cladding layer and the outer cladding layer satisfy the following conditions: Δ1>Δ3>Δ5>Δ2>Δ4; Wherein, Δ1 is the relative refractive index difference of the core layer, Δ2 is the relative refractive index difference of the depression layer, Δ3 is the relative refractive index difference of the first inner cladding layer, Δ4 is the relative refractive index difference of the second inner cladding layer, Δ5 is the relative refractive index difference of the outer cladding layer, the radius of the core layer is R1, the radius R1 of the core layer is 2.0-3.0μm; the radius of the depression layer is R2, R2:R1=2.5-3.0, the radius of the first inner cladding layer is R3, R3:R1=4.0-4.7, the radius of the second inner cladding layer is R4, R4:R1=4.7-5.3, and the radius R5 of the outer cladding layer is 62.5μm.

2. The short-wavelength cutoff, low-macro-bend-loss, non-zero-dispersion-shifted single-mode optical fiber according to claim 1, characterized in that: The core layer is doped with germanium, and the relative refractive index difference Δ1 of the core layer is 0.520%-0.550%.

3. The short-wavelength cutoff, low-macro-bend-loss, non-zero-dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The depression layer is doped with fluorine, and the relative refractive index difference Δ2 of the depression layer is-0.055% to-0.005%.

4. The short-wavelength cutoff, low-macro-bend-loss, non-zero-dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The first inner cladding layer is doped with germanium, and the relative refractive index difference Δ3 of the first inner cladding layer is 0.100%-0.200%.

5. The short-wavelength cutoff, low-macro-bend-loss, non-zero-dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The second inner cladding layer is doped with fluorine, and the relative refractive index difference Δ4 of the second inner cladding layer is-0.150% to-0.055%.

6. The short-wavelength cutoff, low-macro-bend-loss, non-zero-dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The outer cladding layer is a pure silica glass layer, and the relative refractive index difference Δ5 is 0.

7. The short-wavelength cutoff, low-macro-bend-loss, non-zero-dispersion-shifted single-mode optical fiber according to claim 1 or 2, characterized in that: The optical fiber has attenuation ≤0.400 dB / km at 1383 nm waveband, attenuation ≤0.190 db / km at 1550 nm waveband, attenuation ≤0.204 db / km at 1625 nm waveband; mode field diameter at 1550 nm is 9.2 ~ 9.5 μm, cabling cutoff wavelength ≤1250 nm, fiber zero dispersion wavelength is 1322 ~ 1520 nm, 1530-1565 nm dispersion is 2.0 ~ 5.5 ps / nm·km, 1575-1625 nm dispersion is 4.5 ~ 10.2 ps / nm·km, zero dispersion slope ≤0.075 ps / nm 2 ·km; the bending additional loss of the optical fiber after winding 100 turns at a diameter of 60 mm is less than 0.015 dB at 1550 nm, 1580 nm and 1625 nm waveband.

8. Use of a short-wavelength cutoff, low-macro-bend-loss, non-zero-dispersion-shifted single-mode optical fiber according to any one of claims 1 to 7, characterized in that: The optical fiber is applied to the fields of communication, laser or sensing.

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