Dehydroxylation annealing method for large-sized optical fiber preforms

Abstract

The invention discloses a dehydroxylation annealing method for large-sized optical fiber preforms. The method comprises the following steps: 1) placing the optical fiber preforms in an annealing furnace; 2) performing four-stage heating on the optical fiber preforms to a destressing temperature; 3) performing heat preservation; and 4) performing four-stage cooling on the optical fiber preforms toa cooling temperature. According to the method provided by the invention, the preforms are subjected to four-stage gradual heating to the destressing temperature, so that the thermal stability of thepreforms can be guaranteed; through four-stage gradual cooling, the purpose that heat in the preforms can be gently and uniformly emitted can be effectively guaranteed; and heating and cooling are performed under vacuum environment, and compared with the non-vacuum environment, the vacuum state is more conducive to separation of residual He and hydroxyl in the optical fiber preforms, and has a better effect.

Description

[0001] This application is a divisional application with an application date of January 5, 2017, an application number of 201710008217.0, and an invention title of "Dehydroxylation annealing method and device for large-sized optical fiber preforms". technical field [0002] The invention relates to the field of optical fiber manufacturing, in particular to a dehydroxylation annealing method and device for a large-size optical fiber preform. Background technique [0003] Large-size optical fiber preforms usually refer to optical fiber preforms with a diameter of more than 120mm and a length of more than 1500mm. Large-size optical fiber preforms are manufactured by external vapor deposition (OVD), and there will be a certain amount of hydroxyl groups in addition to internal stress. (OH), which will lead to excessive attenuation, fiber breakage, F change, etc. during the drawing process of the optical fiber preform. In view of the above situation, in the prior art, a single lar...

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Problems solved by technology

[0005] In order to solve the problems existing in the prior art, the present invention provides a dehydroxylation annealing method for a large-sized optical fiber preform, which can effectively solve the problem of new thermal stress generated after the optical fiber preform is reheated to remove thermal stress, and at the same time can make Hydroxyl content remains within a reasonable range

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