阅读说明：本技术 耐高压低弯曲损耗的光纤 (High pressure resistant low bend loss optical fiber ) 是由 蒋新力 许维维 范艳层 成煜 王见青 沈一春 *** 曹珊珊 徐海涛 于 2018-06-14 设计创作，主要内容包括：本发明提供一种耐高压低弯曲损耗的光纤,所述光纤包括芯层、内包层、下陷层及外包层,所述芯层掺有SiO<Sub>2</Sub>和GeO<Sub>2</Sub>,所述芯层的半径由所述芯层中心向外延伸距离R1形成,所述芯层的折射率为n1,所述内包层的宽度为所述芯层边缘R1处向外延伸R2-R1的距离,所述内包层的剖面通过掺少量Ge和F形成,所述内包层的折射率为n2,所述下陷层从所述内包层外边缘向外深掺F形成,所述下陷层的宽度和折射率分别为R3-R2和n3,所述外包层的厚度和折射率分别为Rc-R3和nc,所述光纤的折射率剖面为阶跃型分布。本发明提供的光纤在11000米深水中仍能使光纤传输性能不受影响。(The invention provides an optical fiber with high pressure resistance and low bending loss, which comprises a core layer, an inner cladding layer, a sunken layer and an outer cladding layer, wherein the core layer is doped with SiO 2 And GeO 2 The radius of the core layer is formed by the distance R1 extending outwards from the center of the core layer, the refractive index of the core layer is n1, the width of the inner cladding layer is the distance R2-R1 extending outwards from the edge R1 of the core layer, the section of the inner cladding layer is formed by doping a small amount of Ge and F, the refractive index of the inner cladding layer is n2, the depressed layer is formed by doping F outwards from the outer edge of the inner cladding layer, the width and the refractive index of the depressed layer are respectively R3-R2 and n3, the thickness and the refractive index of the Rc are respectively R3 and nc, and the refractive index section of the optical fiber is in a step-type distribution. The optical fiber provided by the invention can still enable the transmission performance of the optical fiber not to be influenced in 11000 m deep water.)

1. An optical fiber having high pressure resistance and low bending loss, comprising: the optical fiber comprises a core layer, an inner cladding layer, a depressed layer and an outer cladding layer, wherein the core layer is doped with SiO₂And GeO₂The radius of the core layer is formed by the distance R1 extending outwards from the center of the core layer, the refractive index of the core layer is n1, the width of the inner cladding layer is the distance R2-R1 extending outwards from the edge R1 of the core layer, the section of the inner cladding layer is formed by doping a small amount of Ge and F, the refractive index of the inner cladding layer is n2, the depressed layer is formed by doping F outwards from the outer edge of the inner cladding layer, the width and the refractive index of the depressed layer are respectively R3-R2 and n3, the thickness and the refractive index of the Rc are respectively R3 and nc, and the refractive index section of the optical fiber is in a step-type distribution.

2. The high pressure resistant low bend loss optical fiber of claim 1, wherein: the radius R1 of the core layer is set between 2.5 mu m and 4 mu m, the width R2-R1 of the inner cladding layer is set between 2.5 mu m and 8 mu m, the width R3-R2 of the depressed layer is set between 3 mu m and 10 mu m, the radius Rc of the outer cladding layer is set between 40 mu m and 125 mu m, the refractive index difference n1-nc between the core layer and the outer cladding layer is between 0.01 and 0.016, the refractive index difference n2-nc between the inner cladding layer and the outer cladding layer is between-0.003 and 0.001, the refractive index difference n3-nc between the depressed layer and the outer cladding layer is between-0.003 and-0.01, and the refractive index difference between the core layer and the depressed layer satisfies n1-n3 & gt 0.016.

3. The high pressure resistant low bend loss optical fiber of claim 1, wherein: the outer cladding layer is a pure quartz glass layer, and the refractive index of the outer cladding layer is 1.4572.

4. The high pressure resistant low bend loss optical fiber of claim 1, wherein: the core layer is doped with GeO₂Is set between 14% and 19%, and the inner cladding is doped with GeO₂Is set between 0.8% and 2%.

5. The high pressure resistant low bend loss optical fiber of claim 1, wherein: the concentration range of the subsidence layer dopant F is set between 0.5% and 1.5%.

6. The high pressure resistant low bend loss optical fiber of claim 1, wherein: the doping depth of the subsidence layer is set to-0.0035 to-0.0053.

7. The high pressure resistant low bend loss optical fiber of claim 1, wherein: the change value of the transmission loss of the optical fiber at the 1550nm wavelength is not more than 0.001dB/km under the pressure of 125 MPa.

8. The high pressure resistant low bend loss optical fiber of claim 1, wherein: the optical fiber has an optical fiber attenuation of less than 0.5dB/km at a wavelength of 1310nm and an attenuation of less than 0.33dB/km at a wavelength of 1550 nm.

9. The high pressure resistant low bend loss optical fiber of claim 1, wherein: the width of the dip layer is greater than one-half of the mode field diameter of the optical fiber.

10. The high pressure resistant low bend loss optical fiber of claim 1, wherein: the deep doping of the sunken layer is realized by MCVD.

Technical Field

The invention relates to the field of optical fibers, in particular to an optical fiber with high pressure resistance and low bending loss.

Background

The ocean contains abundant water, petroleum, natural gas and mineral resources, and has important significance for human survival and development. The optical cable can transmit data stably at a high speed and in a long distance underwater, the transmission rate is high, the diameter is small, the weight is light, the transmission requirements of the data can be basically met by the common optical fiber in a shallow sea area, but with the increase of the submergence depth, the data transmission cannot be finally carried out by the common optical fiber due to the continuous increase of the additional loss. At present, submarine signal transmission is mainly realized by selecting proper reinforcing and gluing materials on the outer layer of a conventional G652 or G657 single-mode optical fiber, and utilizing a reinforcing fiber and gluing one-step forming process to improve the surface radius uniformity so as to reduce microbending loss. The limit submergence depth is 7000 m underwater, the maximum loss change at the 1310nm wavelength is 0.015dB/km, the maximum optical loss change at 1550nm is 0.059dB/km, the data cannot be transmitted due to overlarge loss at 11000 m deep water, and the application requirement at 11000 m deep water cannot be met.

Disclosure of Invention

Accordingly, there is a need for a high pressure resistant low bend loss optical fiber that has low loss and no impact on transmission performance under high pressure conditions.

The invention provides an optical fiber with high pressure resistance and low bending loss, which comprises a core layer, an inner cladding layer, a sunken layer and an outer cladding layer, wherein the core layer is doped with SiO₂And GeO₂The radius of the core layer is formed by the distance R1 extending outwards from the center of the core layer, the refractive index of the core layer is n1, the width of the inner cladding layer is the distance R2-R1 extending outwards from the edge R1 of the core layer, the section of the inner cladding layer is formed by doping a small amount of Ge and F, the refractive index of the inner cladding layer is n2, the depressed layer is formed by doping F outwards from the outer edge of the inner cladding layer, the width and the refractive index of the depressed layer are respectively R3-R2 and n3, the thickness and the refractive index of the Rc are respectively R3 and nc, and the refractive index section of the optical fiber is in a step-type distribution.

Further, the radius R1 of the core layer is set between 2.5 μm and 4 μm, the width R2-R1 of the inner cladding layer is set between 2.5 μm and 8 μm, the width R3-R2 of the depressed layer is set between 3 μm and 10 μm, the radius Rc of the outer cladding layer is set between 40 μm and 125 μm, the refractive index difference n1-nc between the core layer and the outer cladding layer is between 0.01 and 0.016, the refractive index difference n2-nc between the inner cladding layer and the outer cladding layer is between-0.003 and 0.001, the refractive index difference n3-nc between the depressed layer and the outer cladding layer is between-0.003 and-0.01, and the refractive index difference between the core layer and the depressed layer satisfies n1-n3 > 0.016.

Further, the outer cladding layer is a pure quartz glass layer, and the refractive index of the outer cladding layer is 1.4572.

Further, the core layer is doped with GeO₂Is set between 14% and 19%, and the inner cladding is doped with GeO₂Is set between 0.8% and 2%.

Further, the concentration range of the depressed layer dopant F is set between 0.5% and 1.5%.

Furthermore, the doping depth of the sunken layer is set to be-0.0035 to-0.0053.

Further, the optical fiber has a transmission loss variation value of not more than 0.001dB/km at a 1550nm wavelength under a pressure of 125 MPa.

Further, the optical fiber has an optical fiber attenuation of less than 0.5dB/km at a wavelength of 1310nm and an attenuation of less than 0.33dB/km at a wavelength of 1550 nm.

Further, the width of the dip layer is greater than one-half of the mode field diameter of the optical fiber.

Further, the deep doping of the depressed layer with F is realized by MCVD.

According to the high-pressure-resistant low-bending-loss optical fiber, the F is doped in the sunken layer, so that the refractive index difference meets the design requirement, and the GeO in the core layer is reduced₂Doping amount, thereby reducing GeO₂The scattering loss caused by the optical fiber is effectively improved by selecting proper F doping amount and sinking width, the integral additional bending loss is reduced, the optical fiber transmission performance can still be unaffected in 11000 m deep water, and the optical fiber is suitable for remote control of underwater navigation equipment, operation monitoring and remote transmission of large-capacity data such as video signals and the like, and has wide application prospect.

Drawings

Fig. 1 is a schematic cross-sectional view and a schematic refractive index profile of the optical fiber according to an embodiment of the present invention.

Fig. 2 is a data parameter diagram of the cross-sectional structure of the optical fiber according to an embodiment of the present invention.

Fig. 3 is a graph of pressure resistance test data of the optical fiber according to an embodiment of the present invention.

The following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, fig. 1 is a cross-sectional view and a refractive index profile of the optical fiber according to an embodiment of the present invention, the optical fiber is used for signal transmission in 11000 m deep water, and the optical fiber includes a core layer, an inner cladding layer, a depressed layer and an outer cladding layer, which are sequentially clad from inside to outside. In this embodiment, the optical fiber is a single mode optical fiber.

The radius of the core layer is formed by extending a distance R1 outwards from the center of the core layer, the refractive index of the core layer is n1, the radius R1 of the core layer is set to be between 2.5 and 4 microns, and the refractive index difference delta 1 between the core layer and the outer cladding layer is set to be between 0.01 and 0.016. In this embodiment, the core layer is doped with SiO₂And GeO₂The core layer is doped with GeO₂Is set between 14% and 19%, reducing GeO in the core layer₂The doping amount can effectively reduce GeO₂The resulting scattering loss, in other embodiments, the core layer may also be doped with a small amount of F.

The inner cladding layer is coated on the core layer, the distance R2 extending outwards from the center of the core layer is the width of the core layer and the inner cladding layer, namely the width of the inner cladding layer is R2-R1, the refractive index of the inner cladding layer is n2, the width of the inner cladding layer is R2-R1 which is set between 2.5 mu m-8 mu m, and the folding of the inner cladding layer and the outer cladding layerThe difference Δ 2 between-0.003 and 0.001. In this embodiment, the profile of the inner cladding is formed by doping with a small amount of Ge and F, and the inner cladding is doped with GeO₂Is set between 0.8% and 2%.

The depressed layer is coated on the inner cladding, the depressed layer is formed by doping F from the outer edge of the inner cladding to the outside, the doping F is used for reducing the refractive index, the bending loss of the optical fiber is gradually reduced along with the increase of the width and the depth of the depressed layer, the doping depth of the depressed layer is set to be about-0.005, the bending loss performance of the optical fiber can be well improved, in the embodiment, the doping depth of the depressed layer is set to be-0.0035 to-0.0053, the concentration range of the dopant F of the depressed layer is set to be 0.5 to 1.5 percent, and the doping F in the depressed layer is realized through an MCVD process. In other embodiments, doping the recess layer with F may also be achieved by PCVD.

The center of the core layer extends outwards for a distance R3 which is the total width of the core layer, the inner cladding layer and the depressed layer, namely the width of the depressed layer is R3-R2, the width of the depressed layer is R3-R2 and is set between 3 μm and 10 μm, because of the influence of the width of the depressed layer on the cut-off wavelength and the bending loss performance, the width of the depressed layer is set to be larger than one half of the mode field diameter of the optical fiber, the refractive index of the depressed layer is n3, and the refractive index difference delta 3 between the depressed layer and the outer cladding layer is set between-0.003 and-0.01. In the present embodiment, the difference in refractive index between the core layer and the depressed layer satisfies n1-n3 > 0.016.

The radius Rc of the outer cladding is set between 40 μm and 125 μm, the refractive index of the outer cladding is nc, and in this embodiment, the outer cladding is a pure silica glass layer, so the refractive index nc of the outer cladding is 1.4572.

The refractive index profile of the optical fiber is in step-type distribution, the attenuation of the optical fiber at the wavelength of 1310nm is less than 0.5dB/km, the attenuation of the optical fiber at the wavelength of 1550nm is less than 0.33dB/km, and in order to improve the bending resistance of the optical fiber, the cut-off wavelength of the optical fiber is required to be 1450 nm-1530 nm.

The present invention will be further described with reference to specific examples.

Example 1

The radius R1 of the core layer is 2.95 μm, the refractive index difference Delta 1 between the core layer and the outer cladding layer is 0.0152, the thickness R2-R1 of the inner cladding layer is 5.05 μm, the refractive index difference Delta 2 between the inner cladding layer and the outer cladding layer is 0.001, the doping depth of the depressed layer is-0.0035, the width R3-R2 of the depressed layer is 6.1 μm, the radius Rc of the outer cladding layer is 62.5 μm, the refractive index difference n1-n3 between the core layer and the depressed layer is 0.0187, the corresponding mode field diameter of the designed optical fiber is 6.2 μm, and the cut-off wavelength of the optical fiber is 1462 nm.

Example 2

The radius R1 of the core layer is 3.25 μm, the refractive index difference Delta 1 between the core layer and the outer cladding layer is 0.013, the thickness R2-R1 of the inner cladding layer is 4.95 μm, the refractive index difference Delta 2 between the inner cladding layer and the outer cladding layer is-0.0007, the doping depth of the depressed layer is-0.0053, the width R3-R2 of the depressed layer is 5.6 μm, the radius Rc of the outer cladding layer is 62.5 μm, the refractive index difference n1-n3 between the core layer and the depressed layer is 0.0183, the corresponding mode field diameter of the designed optical fiber is 6.6 μm, and the cut-off wavelength of the optical fiber is 1479 nm.

Example 3

The radius R1 of the core layer is 3.65 μm, the refractive index difference Delta 1 between the core layer and the outer cladding layer is 0.0116, the thickness R2-R1 of the inner cladding layer is 4.9 μm, the refractive index difference Delta 2 between the inner cladding layer and the outer cladding layer is-0.0007, the doping depth of the depressed layer is-0.0053, the width R3-R2 of the depressed layer is 5.9 μm, the radius Rc of the outer cladding layer is 62.5 μm, the refractive index difference n1-n3 between the core layer and the depressed layer is 0.83, the corresponding mode field diameter of the designed optical fiber is 7.014 μm, and the cut-off wavelength of the optical fiber is 1484 nm.

Referring to fig. 2 and 3, fig. 2 is a data parameter diagram of the cross-sectional structure of the optical fiber according to embodiment 2, wherein the horizontal axis represents the radius and the vertical axis represents the refractive index. FIG. 3 shows the results of the pressure resistance test of the optical fiber in example 2 under the condition of gradually increasing pressure from 0 to 125MPa, and it can be seen that the optical fiber designed in example 2 has a loss variation value of 0.001dB/km at 1550nm wavelength under the pressure of 125MPa, and can meet the data transmission use requirement under the deep sea of 110 MPa.

According to the high-pressure-resistant low-bending-loss optical fiber, the F is doped in the sunken layer, so that the refractive index difference meets the design requirement, and the GeO in the core layer is reduced₂Doping amount, thereby reducing GeO₂The scattering loss caused by the optical fiber is effectively improved by selecting proper F doping amount and sinking width, the integral additional bending loss is reduced, the optical fiber transmission performance can still be unaffected in 11000 m deep water, and the optical fiber is suitable for remote control of underwater navigation equipment, operation monitoring and remote transmission of large-capacity data such as video signals and the like, and has wide application prospect.

It should be understood by those skilled in the art that the above embodiments are only for illustrating the present invention and are not to be used as a limitation of the present invention, and that suitable changes and modifications of the above embodiments are within the scope of the claimed invention as long as they are within the spirit and scope of the present invention.