Dehydroxylation annealing method and device for large-size optical fiber preform

Abstract

The invention discloses a dehydroxylation annealing method and device for a large-size optical fiber preform. The method comprises the steps of (1) putting the optical fiber preform into an annealing furnace; (2) heating the optical fiber preform to a destressing temperature through heating for four times; (3) carrying out heat preservation; and (4) cooling the optical fiber preform to a cooling temperature through cooling for four times. The optical fiber preform is heated to the destressing temperature through gradual heating for four times, so that the heat stability of the preform can be ensured; the condition that the internal heat of the preform can be slowly and uniformly emitted can be effectively ensured through gradual heating for four times; heating and cooling are carried out in a vacuum environment; and relative to a non-vacuum environment, the vacuum state is more conductive to separation of residual He and hydroxyl in the optical fiber preform and the effect is better.

Description

technical field [0001] 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 [0002] 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 large-size optical fiber preform is suspended in a quartz tube, and the heating element wrapped around the quartz tube is directly heated to a certain temperature, and it is kept warm by preset a holding time, and then directly cooled cooling, so that th...

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Problems solved by technology

[0004] 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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