Method for manufacturing doped optical fibre preform by MCVD (modified chemical vapour deposition)

Abstract

The invention discloses a method for manufacturing a doped optical fibre preform by MCVD (modified chemical vapour deposition), comprising the following steps of: orderly depositing an inner cladding and a loose ash core layer in a deposition tube; reducing the intake port end of the deposition tube to cause the inner diameter of the end to be less than or equal to the inner diameter of the loose ash core layer; heading and snapping the tail end of the deposition tube to close the tail end of the deposition tube; injecting solution containing rare-earth elements or transition metal elements in the deposition tube, and transversally installing the deposition tube on a lathe to soak the loose ash core layer; sintering the loose ash core layer into a glass layer; and melting-reducing the deposition tube, the inner cladding and the loose ash core layer into a solid preform. In the method disclosed by the invention, the deposition tube is horizontally placed to rotationally soak, the purpose of high-concentration doping can be realized only by the need of a small amount of rare-earth solution, and 80-90% of rare-earth solution can be saved, thereby decreasing manufacturing cost. Simultaneously, the distribution of rare-earth elements in the longitudinal direction of preform core layer is enabled to be more uniform, thereby further increasing the rare-earth doping concentration of preform core layer.

Description

technical field [0001] The invention relates to a method for manufacturing an optical fiber prefabricated rod, in particular to a method for manufacturing an optical fiber prefabricated rod whose core layer contains a dopant by using an improved chemical vapor deposition method. Background technique [0002] At present, the manufacture of optical fiber preforms generally adopts vapor deposition technology, including axial vapor deposition (vapor axial deposition, VAD), external vapor deposition (outside vapor deposition, OVD), modified chemical vapor deposition (modified chemical vapor deposition) , MCVD) and plasma chemical vapor deposition (plasma chemical vapor deposition, PCVD). Raw material SiCl for making preform 4 and dopant GeCl 4 With a high vapor pressure, it reacts with oxygen to form SiO after being evaporated by heating or bubbling 2 and GeO 2 , SiO 2 is the main component of the preform, GeO 2 The core layer incorporated into the preform raises its refrac...

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Problems solved by technology

[0006] The technical problem to be solved and the technical task proposed by the present invention are to overcome the problems of large consumption of rare earth solution and uneven longitudinal doping of rare earth in the manufacture of rare earth-doped optical fiber preform by using MCVD combined with solution doping method in the prior art, and provide manufacturing Solution soaking method of rare earth-doped optical fiber preform

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