An ovd deposition cavity device for preparing optical fiber preforms

Abstract

The invention relates to an OVD deposition chamber device for preparing an optical fiber preform, which comprises an air suction pipe, a primary buffer chamber, a secondary buffer chamber and a deposition chamber which are arranged in sequence from top to bottom. The bottom of the deposition chamber is provided with a The air inlet, deposition mandrel and deposition torch are arranged inside the deposition chamber. The deposition chamber is house-shaped: the upper part is trapezoidal, the lower part is square, and the top is butted with the slit of the secondary buffer chamber; the lower part of the secondary buffer chamber is inverted trapezoid ;The primary buffer chamber is a round pipe type, with a supplementary air pipe on the end face, and a supplementary air valve is set on the supplementary air pipe to adjust the opening and closing size of the supplementary air pipe. It is communicated with the secondary buffer chamber up and down; the air exhaust pipe is communicated with the primary buffer chamber through two arc-shaped pipes symmetrically left and right. The present application improves the uniformity of the distribution of the airflow in the deposition chamber along the axial direction of the deposition mandrel, stabilizes the air pressure in the deposition chamber, increases the wrapping area of ​​the torch flame on the deposition mandrel, and increases the SiO2 2 Powder collection rate.

Description

technical field [0001] The present invention relates to OVD deposition in the field of optical fiber fabrication. Background technique [0002] With the rapid development of the communication industry, major manufacturers are competing to expand production capacity, resulting in excess production capacity and nearly halving the price of optical fibers. How to control the production cost of optical fiber and improve the market share has become the key to the survival of enterprises. At present, the mainstream optical fiber preform preparation technology is: VAD+OVD process, that is, the core rod is prepared by the VAD process; the cladding layer is prepared by the OVD process. Among them, the cost of cladding accounts for more than 90% of the cost of the preform. Therefore, under the current situation, how to reduce the cost of the OVD process is the key to forming the competitiveness of enterprises. [0003] The OVD cavity has a significant impact on the cost and quality o...

AI Technical Summary

Problems solved by technology

[0005] 1. The uniformity of cooling gas flow rate distribution in the axial direction of the loose body is not good: the structure of the OVD deposition chamber tends to fluctuate periodically along the axial direction of the loose body because the flow rate of a single lampshade from the center to the outside is high in the middle and low at the side. The outer diameter of the final deposited preform fluctuates, which affects the quality of the preform, such as the poor stability of cut-off wavelength and mode field diameter

[0006] 2. The collection efficiency of soot is low: the existing OVD deposition chamber structure, the flow direction of the cooling gas cannot be effectively controlled, resulting in a small contact area between the deposition flame and the soot, that is, the wrapping area of ​​the soot by the deposition flame is small, A lot of SiO 2 The powder is not deposited on the surface of the loose body, but is directly sucked away with the airflow, resulting in a low collection efficiency, generally between 45% and 50%.

[0007] 3. The cavity pressure cannot be controlled online: the existing OVD deposition cavity device adopts an offline control method for the cavity pressure

In such a state, the pressure of the cavity will drop due to the continuous growth of the loose body or the continuous accumulation of dust in the air flow pipe, which may eventually cause the tail gas generated by the deposition to be unable to be pumped out in time, a large amount of dust will accumulate in the deposition cavity, and the remaining dust will fall. to the soot, forming impurity defects in the preform

[0008] 4. Not conducive to cleaning: the current deposition chamber has airflow dead angles, and most of these airflow dead angles are also hygienic dead angles that are difficult to be purged

Especially the back of the exhaust hood is easy to accumulate dust. If the dust falls on the loose body during the deposition process, it is easy to form impurity defects such as "white spots" in the soot

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