Method for preparing large-size optical fiber preform

Abstract

The invention relates to a method for preparing a large-size optical fiber preform, comprising the following steps: a mandril is prepared by the intra-tube chemical vapor deposition method, and the mandril comprises a fiber core layer, or a fiber core layer and part of inner cladding layer; the mandril is used as a target rod, a SiO2 loose body is prepared on the target rod by the VAD (Vapor Axial Deposition) method, and an inner cladding layer or part of inner cladding layer is formed; a primary optical fiber preform with uniform structure is obtained; and the primary optical fiber preform is used as the target rod, a SiO2 outer cladding layer is deposited on the primary optical fiber preform through the OVD (Outside Vapor Deposition) method, after the deposition is finished, and the primary optical fiber preform is sintered into a transparent optical fiber preform. The method is combined with the advantages of various deposition techniques, the disadvantages of the techniques are reasonably avoided, and the unification of high deposition rate, high performance and low cost is realized. The method is not only suitable for preparing a common single-mode optical fiber with a simple section, but is also suitable for preparing special optical fibers with precise and complicated sections.

Description

technical field [0001] The invention relates to a method for preparing an optical fiber preform by utilizing the cost advantage of an external deposition method and the precision advantage of an in-tube method, and belongs to the field of optical fiber manufacturing. Background technique [0002] Optical fiber preforms are used to prepare optical fibers for communication transmission media. Optical fiber manufacturing technology includes multiple links and processes, and preform rod manufacturing is one of the main processes. With the development of optical fiber preform technology, in order to improve the production efficiency of optical fibers, commercial preforms are currently moving towards the direction of making larger-sized optical fiber preforms. Larger-sized (diameter) preforms usually adopt the "two-step method" Manufacturing process, the first step is the manufacture of mandrel; the second step is outsourced manufacturing and rod forming. Among them, the manufac...

AI Technical Summary

Problems solved by technology

The casing method has the following disadvantages: large-sized casing requires high geometric accuracy, the manufacturing process is complicated, and material loss during casing processing leads to increased costs

However, the deposition rate is relatively slow compared to the OVD method

And using the VAD method alone, the quartz particles are adhered to the substrate and grow vertically downward, and the structure of the soot body is fragile. The size and weight of the soot body produced under the condition of no target rod are limited, and it is difficult to manufacture a large preform

[0006] In-tube PCVD and MCVD are suitable for preparing high-precision preforms with complex waveguide structures, but the deposition rate is low, and large-scale preforms cannot be prepared alone

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