Small-outer-diameter bending insensitive single-mode optical fiber

Abstract

The invention relates to a small-outer-diameter bending insensitive single-mode optical fiber. The optical fiber comprises a core layer and a cladding layer, the diameter 2R1 of the core layer is 7.4to 7.8 mu m; the relative refractive index difference is delta 1; the cladding sequentially comprises a sunken inner cladding and an outer cladding from inside to outside; the diameter 2R2 of the sunken inner cladding is 34-40 [mu] m; the refractive index of the sunken inner cladding is distributed in a sunken shape; the minimum relative refractive index difference is delta 2 min; the refractive index difference delta total between the core layer and the inner cladding is equal to delta 1-delta 2 min; the range of delta total is 0.44%-0.52%, and the range of delta total is 0.44%-0.52%; and therelative refractive index difference distribution relationship between the core layer and the sunken inner cladding meets the following condition: the relative refractive index difference distribution relationship is shown in the specification. The absolute value of delta 1 / delta 2 min is 4.5-6.5; wherein the outer cladding is a pure silicon dioxide outer cladding, the relative refractive index difference delta 3 of the outer cladding is 0%, the diameter 2R3 of the outer cladding is 123-125 [mu] m, the outer cladding is coated with the inner coating layer and the outer coating layer, the diameter 2R4 of the inner coating layer is 163-170 [mu] m, and the diameter 2R5 of the outer coating layer is 190-195 [mu] m. Through optimization of a section structure and a coating process, the opticalfiber not only has a large mode field diameter, but also has low bending loss and good micro-bending performance.

Description

technical field [0001] The invention relates to a bending-insensitive single-mode optical fiber with a small outer diameter, which belongs to the field of optical communication transmission. Background technique [0002] With the continuous development of FTTH, in many cases, fiber-to-the-home will face complex construction environments such as corridors, corners or indoors. The normal transmission of signals, on the other hand, with the increasing shortage of pipeline resources and the demand for aesthetic (invisible) use of optical fiber indoors, it is required that the outer diameter of the optical fiber can be reduced while ensuring the same microbending performance as the traditional outer diameter optical fiber. [0003] G.657.A2 optical fiber is used under the condition of at least 7.5mm bending radius and FTTH use environment. In order to make the optical fiber have better bending performance, the usual method is to reduce the fiber mode field diameter or increase th...

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Problems solved by technology

[0008] European patent EP2057493A describes a kind of optical fiber whose bending performance meets G.657.A2. It is designed for the outer cladding to be depressed. In order to meet the requirement of bending insensitivity, the relative refractive index of the sunken outer cladding Δ<-0.63%. This design is easy to cause the cut-off wavelength Excessively high and high dispersion, and multi-path crosstalk problems are prone to occur during fiber transmission, which will affect the compatibility of the fiber. In addition, the deep cladding of the fiber also increases the manufacturing cost of the fiber, which is not conducive to the large-scale use of this type of fiber. application

[0009] US patent US7099545 ​​describes a G.657.A2 optical fiber with a core refractive index: 0.55%<Δ1<0.7%, a depressed cladding refractive index: Δ2<-0.2%, a high core refractive index and a depressed cladding The refractive index of the layer is very low. The mode field diameter of the optical fiber at the wavelength of 1310nm is equal to or greater than 6.6μm. The mode field diameter is too low and does not match the mode field diameter of G.652.D. Fiber Compatible

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