Optical fiber preform and its manufacturing method

Abstract

The invention provides a method for manufacturing an optical fiber preform, comprising the following steps: providing a core layer, depositing a first inner cladding layer and a second inner cladding layer sequentially on the surface of the core layer; soaking and hovering in a heating zone as a whole, dehydroxylation, Doping with fluorine, vitrification and sintering to form a quartz glass rod; drilling and honing the second inner cladding layer of the quartz glass rod; forming a lower concave layer; forming an outer cladding on the surface of the quartz glass rod forming the lower concave layer layer to obtain an optical fiber preform. The optical fiber preform in the present invention has the characteristics of large preform size, precise control of fluorine doping in the lower concave layer, bending performance when the small radius R≤5mm is realized, low optical fiber attenuation, good dispersion performance, and zero dispersion wavelength≤1320nm. The dynamic fatigue parameter Nd value of the point bending method test reaches 28-32, which meets and exceeds the index of ITU‑TG657B3.

Description

technical field [0001] The invention belongs to optical communication technology, and in particular relates to an optical fiber preform rod and a manufacturing method thereof. Background technique [0002] With the continuous development of optical fiber transmission technology, fiber-to-the-home has become an important direction of communication access network construction. In the actual laying of FTTx optical fiber lines, it is often necessary to carry out optical fiber laying operations in small or narrow spaces, especially the invisible optical cables and FTTD (fiber to the table) that have appeared in recent years. At this time, the optical fiber should have a high bending resistance in a small bending radius. Therefore, it is necessary to design, develop and manufacture bend-insensitive optical fibers with better performance to meet the requirements of FTTx network construction and device miniaturization. According to the ITU-T G.657 optical fiber standard that is no...

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Problems solved by technology

[0006] 1. The in-tube deposition method (MCVD, PCVD) is limited by the process conditions and size, the water peak absorption attenuation is large, and the manufacturing cost is high, and the size of the preform is small, so it cannot be scaled up;

[0007] 2. In the currently used VAD manufacturing core rod process, the known patents CN2010106090.0, CN201210243973.9, US5032001, US7043125b2, CN176680, CN104991306 patents improve the macrobending performance of the optical fiber to a certain extent by realizing the design of the lower concave layer , when the bending radius is less than or equal to 10mm, the macrobending performance cannot meet the requirements of G.657.B3; at the same time, it is found that the depth and width of the concave layer will affect the macrobending performance, fiber cut-off wavelength and dispersion performance, so The width and depth of the recessed fluorine-doped layer prepared by traditional VAD cannot be precisely controlled

[0008] 3. In patent CN201310300024.4, the core layer component is SiO 2 -GeO 2 -F-Cl, according to the Rayleigh scattering principle of optical fiber silica glass, the more the core layer is doped, it is not conducive to ensuring the uniformity and consistency of the material, and the attenuation value of the optical fiber is also greater

Although it meets the G.657.B3 attenuation index, it cannot meet the existing market demand. It not only meets the G.657.B3 macrobend, but also meets the G652D attenuation and dispersion index.

At the same time, in the methods disclosed in patents CN201310300024.4, ZL200910062855.6, and CN104991306, only the design method is mentioned, but the manufacturing method of the optical fiber preform is not specifically mentioned. difficult to implement

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