Optical Fiber Glass Base Material Fluorine Doping
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Solution Overview
Problem
The existing methods for manufacturing glass base materials for optical fibers result in fluctuating optical properties along the longitudinal direction due to uneven fluorine doping, particularly affecting the upper and lower ends of the glass base material.
Innovation Solution
A manufacturing method involving a preliminary fluorine doping step followed by heat treatment in a chlorine-based and inert gas atmosphere, with controlled temperature and gas mixtures, to achieve uniform fluorine distribution and suppress optical property fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fluorine is doped into the porous glass base material during sintering using conventional methods, then fluorine doping is achieved, but the doping amount distribution fluctuates in the longitudinal direction of the glass base material
Solution Approach 1:
The patent applies preliminary fluorine doping to the porous glass base material before sintering. By pre-doping the ends of the base material with fluorine, the invention compensates for the uneven fluorine distribution that would otherwise occur during sintering, ensuring uniform fluorine content throughout the longitudinal direction of the final glass base material.
Solution Approach 2:
The patent applies different fluorine doping concentrations to different regions of the porous glass base material. Specifically, the ends of the base material receive preliminary fluorine doping with a concentration different from the central portion, creating local quality variations that result in uniform overall distribution after sintering.
2Productivity
If conventional sintering methods are used, then glass base material is produced, but optical properties fluctuate in the longitudinal direction particularly at upper and lower ends
Solution Approach 1:
The patent performs preliminary fluorine doping on the porous glass base material before sintering to prevent optical property fluctuations. By pre-treating the ends of the base material with fluorine, the invention ensures that the final sintered glass has uniform optical properties throughout its length, eliminating the longitudinal variations that typically occur at the upper and lower ends.
3Device complexity
If a single heat treatment step is used, then the process is simple, but uniform fluorine distribution in the longitudinal direction cannot be achieved
Solution Approach 1:
The patent segments the heat treatment process into two distinct steps: a first heat treatment step for dehydration in a chlorine-containing gas atmosphere, and a second heat treatment step for transparent vitrification in a fluorine-containing gas atmosphere. This segmentation allows each step to perform its specific function optimally, resulting in uniform fluorine distribution throughout the glass base material.
Solution Approach 2:
The patent changes the atmospheric parameters between heat treatment steps. The first step uses a chlorine-containing gas atmosphere for dehydration, while the second step uses a fluorine-containing gas atmosphere for vitrification and fluorine doping. This parameter change enables controlled fluorine incorporation at different stages of the process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces optical fibers with reduced longitudinal variation in optical properties, ensuring consistent performance across the fiber length.
Implementation Method 1
a first heat treatment step in which the porous glass base material inserted in a vessel of a sintering furnace is heated by a heater installed around the periphery of the vessel while being raised or lowered in the longitudinal direction in a chlorine-based gas containing atmosphere in the vessel of the sintering furnace
Implementation Method 2
a preliminary fluorine doping step prior to the second heat treatment step in which one or both ends of the porous glass base material are heated by the heater in a fluorine-based gas containing atmosphere in the vessel
Implementation Method 3
a second heat treatment step in which the porous glass base material is heated by the heater to obtain a transparent glass body while being raised or lowered in the longitudinal direction in an inert gas containing atmosphere in the vessel after the first heat treatment step
Implementation Method 4
then subjected to a transparent vitrification process to obtain a transparent glass base material
Data Source
Figure 1
Figure 2A~2E
Figure 3~4
AI summary
A manufacturing method of glass base material for optical fiber that can obtain glass base material for optical fiber with reduced fluctuation in optical properties in the longitudinal direction is provided. The manufacturing method of glass base material for optical fiber includes: a first heat treatment step in which the porous glass base material inserted in a vessel of a sintering furnace is heated by a heater installed around the periphery of the vessel while being raised or lowered in the longitudinal direction in a chlorine-based gas containing atmosphere in the vessel of the sintering furnace; a second heat treatment step in which the porous glass base material is heated by the heater to obtain a transparent glass body while being raised or lowered in the longitudinal direction in an inert gas containing atmosphere in the vessel after the first heat treatment step; and a preliminary fluorine doping step prior to the second heat treatment step in which one or both ends of the porous glass base material are heated by the heater in a fluorine-based gas containing atmosphere in the vessel.