Optical Fiber Preform Collapse Sequencing for Alkali Uniformity
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Solution Overview
Problem
The variation in concentration of alkali metal elements in the longitudinal direction during the manufacturing of optical fiber preforms leads to inconsistent transmission losses and potential defects due to changes in the diameter of alkali-doped portions, which cannot be accurately controlled.
Innovation Solution
A method involving controlled collapsing and rod-in-collapse processes with alternating heat source traversing directions to maintain a consistent concentration of alkali metal elements, ensuring a difference in traversing directions is 1 or less, thereby stabilizing the diameter and concentration of alkali-doped portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkali metal elements are doped into the core portion to reduce viscosity and promote glass rearrangement, then transmission loss caused by Rayleigh scattering is reduced, but the concentration of alkali metal elements varies in the longitudinal direction leading to inconsistent transmission losses
Solution Approach 1:
The patent applies the inversion principle by reversing the traversal direction of the heat source between collapsing and rod-in-collapse processes. Instead of always traversing in the same direction, the method alternates directions to compensate for diameter variations of alkali-doped portions, thereby suppressing concentration variation in the longitudinal direction and achieving consistent transmission loss characteristics.
Solution Approach 2:
The patent changes the operational parameter of heat source traversal direction to control the behavior of alkali-doped portions during manufacturing. By adjusting the traversal direction (first direction vs. second direction) and controlling the difference in traversal counts to be 1 or less, the method achieves uniform alkali metal concentration distribution and consistent transmission loss.
2Ease of manufacture
If the collapsing and rod-in-collapse processes are performed with a heat source traversing in the same direction multiple times, then the manufacturing process is simplified, but the diameter of alkali-doped portions varies significantly leading to defective products
Solution Approach 1:
The patent introduces direction alternation in the heat source traversal during collapsing and rod-in-collapse processes. By reversing the traversal direction between processes and controlling the traversal count difference to be 1 or less, the method suppresses diameter variation of alkali-doped portions while maintaining manufacturing feasibility.
Solution Approach 2:
The patent implements a feedback mechanism by monitoring and controlling the traversal direction and count of the heat source. The method ensures that the difference between the number of traversals in the first direction and the second direction is 1 or less, providing precise control over the diameter of alkali-doped portions and achieving consistent manufacturing quality.
3Device complexity
If the heat source traverses in the first direction only during collapsing and rod-in-collapse, then the process control is simplified, but the concentration variation of alkali metal elements cannot be suppressed leading to increased transmission loss
Solution Approach 1:
The patent applies the inversion principle by alternating the traversal direction of the heat source between collapsing and rod-in-collapse processes. This directional reversal suppresses concentration variation of alkali metal elements in the longitudinal direction, achieving stable transmission loss characteristics without significantly increasing process control complexity.
Solution Approach 2:
The patent changes the traversal direction parameter of the heat source to control alkali metal concentration distribution. By controlling the difference in traversal counts between first and second directions to be 1 or less, the method achieves reliable transmission loss stability while maintaining manageable process complexity.
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
This approach effectively suppresses variations in alkali metal concentration and diameter, resulting in stable transmission losses and reduced manufacturing defects across the optical fiber preform.
Implementation Method 1
collapsing the first glass pipe after the doping by heating, thereby obtaining a glass rod
Implementation Method 2
integration of the rod and the second glass pipe by heating
Implementation Method 3
doping at least one element selected from an alkali metal group consisting of an alkali metal element and an alkaline earth metal element into an inner surface of a first glass pipe
Implementation Method 4
the viscosity of the core is reduced and the rearrangement of glass is promoted when an optical fiber is manufactured by drawing an optical fiber preform
Data Source
AI summary
The method for manufacturing an optical fiber preform, the method includes: doping at least one element selected from an alkali metal group into a first glass pipe; collapsing the first glass pipe, thereby obtaining a glass rod; and performing at least one rod-in-collapse. The collapsing and the performing the at least one rod-in-collapse are performed while traversing an external heat source in a first direction from a first end toward a second end of the glass rod or in a second direction from the second end toward the first end. In the collapsing and the performing the at least one rod-in-collapse, a difference between the number of times of the traversing in the first direction and the number of times of the traversing in the second direction is 1 or less.