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Method of manufacturing glass preforms for optical fibers

A technology for preforms and optical fibers, which is applied in the field of manufacturing silica-based glass preforms, glass core preforms, and optical fibers including fluorine-doped regions, can solve the problems of surface corrosion of quartz glass, formation of pits in muffle tubes, and tube formation. Problems such as wall thickness reduction

Active Publication Date: 2022-06-07
PRYSMIAN SPA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These gases react with the quartz glass, causing corrosion of the quartz glass surface, which can lead to the formation of pits in the muffle tube and / or to a continuous reduction in tube wall thickness

Method used

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  • Method of manufacturing glass preforms for optical fibers
  • Method of manufacturing glass preforms for optical fibers
  • Method of manufacturing glass preforms for optical fibers

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0127] Example 1 (comparison)

[0128] Insert the soot core preform into the reference Figure 4 Described in the type of dehydration consolidation furnace. Simultaneous dehydration and fluorine doping stages were performed by placing the preform in the upper hot zone set at 1000-1100 °C, while the lower hot zone was set at 1450 °C. The soot core preform was held in the upper hot zone for 1.5 hours while rotating at 5 rpm and exposed to 80 L / min of helium + 1.5 L / min of chlorine + 0.3 L / min of SF 6 in the atmosphere of the mixed gas flow.

[0129] The dehydrated and fluorine-doped soot core preform was then driven downward at a speed of 4 mm / min towards the lower hot zone of the furnace set at a temperature of 1550°C while in a flow of 20 L / min of helium at 1 rev / min The speed is rotated until the entire preform passes through the lower hot zone for consolidation. At the beginning of the descent towards the lower hot zone, a vacuum is created in the central longitudinal ho...

example 2

[0133] Example 2 (comparison)

[0134] Insert the soot core preform into the reference Figure 4 Described in the type of dehydration consolidation furnace. As in Example 1, the dehydration and fluorine doping stages were performed simultaneously, and then the central longitudinal pores were consolidated and closed simultaneously, except that the treatment time for the simultaneous dehydration and fluorine doping stages was 4.5 hours.

[0135] The average value of optical attenuation is the same as in Example 1.

[0136] Image 6 The measured refractive index profiles of the grooved regions of the mandrels produced according to this example are shown. The longer processing time combined with fluorine doping and dehydration resulted in wider trench regions near the cladding layer.

[0137] Even more pronounced pit formation was observed on the muffle due to the 3 times the doping stage as in Example 1.

example 3

[0139] Insert soot core preforms such as figure 2 In the first muffle of a first furnace of the type shown with a single hot zone. The fluorine doping stage is carried out by placing the soot core preform in a single hot zone set to a temperature of 1000°C. The soot core preform was kept in this single hot zone for a doping time of 1 hour while rotating at 5 rpm and exposed to helium flowing at a flow rate of 20 L / min and a flow rate of 0.3 L / min SF 6 in the atmosphere. then stop sf 6 flow, and the preform was kept in the furnace muffle for 1 hour to vent fluorine-containing gas.

[0140] Subsequently, the fluorine-doped soot preform is removed from the first furnace and inserted into the second muffle of the second furnace, which is Figure 4 A standard dehydration consolidation furnace of the type shown. The second furnace was the same furnace used in the comparative example, but fitted with a new quartz muffle.

[0141] The dehydration stage was carried out by placi...

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Abstract

A method of manufacturing a fluorine-doped glass preform for an optical fiber, comprising: exposing a soot preform (11) in a first elongated chamber (28; 44) of a first furnace (30; 40) to an atmosphere containing In an atmosphere of fluorine gas and substantially free of chlorine to obtain a fluorine-doped soot preform, the first elongated chamber (28; 44) has a single isothermal hot zone maintained at a doping temperature of 800°C to 1200°C (33; 53); exposing the fluorine-doped soot preform (11) in a second elongated chamber (61) of a second furnace (60) to an atmosphere comprising a gas containing chlorine and substantially free of fluorine to make It dehydrates, and the second elongated chamber has an upper thermal zone (66') at a dehydration temperature of 1000°C to 1350°C and a lower thermal zone (67') at a consolidation temperature of 1500°C to 1650°C, wherein Dehydration takes place in the upper hot zone (66') of the second furnace, and the fluorine-doped soot preform (11) is consolidated by moving it down into the lower hot zone of the second furnace to obtain fluorine-doped Glass preforms.

Description

technical field [0001] The present disclosure relates to a method of manufacturing a glass preform for an optical fiber. In particular, the present disclosure relates to a method of fabricating a silica-based glass preform to fabricate an optical fiber including a fluorine-doped region. More particularly, the present disclosure relates to a method of making a glass core preform. Background technique [0002] Silica-based glass preforms for drawing optical fibers, especially telecommunications optical fibers, can be produced from soot preforms according to well-known manufacturing methods, such as external vapor deposition (OVD) and vapor axial deposition (VAD). Soot preforms are generally cylindrical, porous precursors made wholly or partly from soot particles, the density of which usually does not exceed 0.7 gr / cm 3 , thus significantly lower than about 2.2 gr / cm for silica glass 3 density of. The deposited silica soot can be doped with elements such as germanium and fl...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C03B37/012
CPCC03B37/01205C03B37/01446C03B37/01453C03B37/0146C03B2201/12
Inventor V·卡罗纳S·格列科I·迪詹巴蒂斯塔F·科基尼A·斯基亚福
Owner PRYSMIAN SPA
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