Method for manufacturing large-size low-water-peak prefabricated rod

Abstract

The invention relates to a method for preparing a large-size low-water-peak prefabricated rod, which comprises the following steps of: 1, depositing a core layer and partial cladding material in a quartz glass lining tube by using an in-tube chemical vapor deposition method to meet the requirement of a waveguide structure and optimize fluorine doped components, wherein the F-doped refractive index contribution of an inner cladding layer prepared by an in-tube method is not more than -0.10 percent and the F-doped refractive index contribution of the core layer is not more than -0.03 percent; 2, melting and shrinking the quartz glass lining tube deposited with the core layer and the partial cladding material at the temperature of between 1,900 and 2,300DEG C into a solid core rod, and manufacturing a core rod of which the b / a is more than or equal to 1.5 and less than or equal to 3.0 and the c / a is more than or equal to 2.3 and less than 4.5; 3, cladding a proper amount of uniform quartz loose body on the outer surface of the core rod directly by using an outside vapor deposition method to obtain a loose body prefabricated rod; and 4, slowly heating the loose body prefabricated rod at high temperature for dehydration, and sintering to obtain the transparent large-size low-water-peak prefabricated rod. The advantage of doping of the in-tube method and the advantage of large size of the outside method are combined, the process is simple, and the method is suitable for producing large-size low-water-peak prefabricated rods at low cost on a large scale.

Description

technical field [0001] The invention relates to a method for preparing an optical fiber preform by utilizing the advantage of the in-tube doping process and adopting the core rod direct outsourcing technology, that is, a method for manufacturing a large-scale low water peak optical fiber preform by using the in-tube method and the Soot direct outsourcing process, belonging to the field of optical fiber manufacturing. Background technique [0002] Optical fiber preforms are used to prepare optical fibers for communication transmission by drawing. Optical fiber manufacturing technology includes many links and processes, of which there are two main processes, one of which is the manufacture of preform rods. At present, the production of commercial preforms generally adopts a "two-step" manufacturing process, that is, the first step is the manufacture of mandrels; the second step is outsourced manufacturing and rod formation. Among them, the manufacturing process of the mandrel...

AI Technical Summary

Problems solved by technology

However, this casing method has the following disadvantages: the large-sized casing requires high geometric accuracy, the manufacturing process is complicated, and the material loss during the casing processing leads to an increase in cost.

However, in order to prepare large preforms with low water peaks, the technical route of the extra-tube method + Soot direct outsourcing method also has the following shortcomings: As we all know, the extra-tube method is difficult to achieve complex refractive index profiles and Ge / F co-doping process and other aspects are obviously insufficient compared with the in-tube method. Therefore, the domestic production of large-scale preforms with low water peaks using the out-of-tube method + Soot direct outsourcing method mainly produces simple step single-mode optical fibers (typically ITU -G.652.D), the product type is difficult to switch; in addition, due to the relatively simple design of the mandrel doping material, in order to avoid the hydroxyl group on the surface of the mandrel from diffusing to the core during the dehydration and sintering process during the direct outsourcing process, the low water During the process design of peak optical fiber core rod process, it is generally necessary to reserve a sufficiently large inner cladding and core diameter ratio (ie T / a). At present, the calculated theoretical value can reach T / a not less than 3.8, and the typical value is generally around 4.5. This feature significantly reduces the annual production capacity of a single mandrel equipment converted into optical fibers

[0007] Chinese patent CN00128165.8 discloses a method for making a large-scale optical fiber preform, which is characterized in that the core and cladding materials are deposited in a quartz glass tube by an in-tube method and melted into a core rod, and then the outer cladding material is deposited by an external method and sintered into a Transparent glass rod, the patent does not involve the specific doping content of the fiber core and cladding, does not involve the specific process parameters of the PCVD process and fiber parameters

Chinese patent CN01128430.7 discloses a method for manufacturing an optical fiber preform, which is characterized in that the optical fiber preform is manufactured by mixing plasma chemical vapor deposition and external vapor deposition, but this patent does not involve plasma chemical vapor deposition Specific process parameters, not related to optical fiber structure parameters and optical fiber optical performance parameters

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