Optical Fiber Preform Interface Treatment
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Solution Overview
Problem
Conventional methods for producing optical fiber preforms and fibers often result in irregularities, contaminants, and atomic defects at the interface between the core rod and the overclad tube/cylinder, leading to increased attenuation and light scattering losses.
Innovation Solution
A method involving the steps of providing a glass tube and core rod, inserting the core rod into the glass tube, heating to cause the tube to collapse and adhere to the core rod, and treating the interface gap by establishing a vacuum pressure, increasing it with oxygen-enriched air, and then re-establishing vacuum pressure to reduce contaminants and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional RIT and RIC methods are used to form optical fiber preforms, then the preform production process is simple and straightforward, but contaminants, impurities and atomic defects are introduced at the interface between the core rod and the overclad tube/cylinder
Solution Approach 1:
The interface gap is evacuated and filled with reactive gas (oxygen, nitrogen, or chlorine) before the overclad tube collapses onto the core rod. This preliminary treatment prevents contaminants and atomic defects from forming at the interface during the collapsing process, thereby improving interface quality without compromising manufacturing simplicity
Solution Approach 2:
The interface gap is evacuated to create a vacuum environment, and then filled with reactive gas that forms an inert or controlled atmosphere during the collapsing process. This controlled atmosphere prevents contamination and atomic defects at the interface, resolving the contradiction between simple manufacturing and high interface quality
2Manufacturing precision
If the overclad tube is collapsed onto the core rod without interface treatment, then the manufacturing process is fast and efficient, but irregularities such as voids, air lines and bubbles are formed at the interface
Solution Approach 1:
The interface gap is evacuated and filled with reactive gas before the collapsing process begins. This preliminary action ensures uniform interface formation by preventing voids, air lines and bubbles from forming during collapse, while adding only minimal steps to the overall manufacturing process
Solution Approach 2:
The mechanical collapsing process is supplemented with gas pressure control and vacuum evacuation. By using gas pressure to control the collapsing process and evacuate the interface gap, the method achieves uniform interface formation without significantly increasing mechanical device complexity
3Manufacturing precision
If reactive gas is introduced into the interface gap during collapsing, then contaminants and atomic defects are reduced, but the process time and complexity increase
Solution Approach 1:
The interface gap is evacuated and filled with reactive gas before the collapsing process begins, rather than during the collapse itself. This timing allows the gas treatment to be completed in advance, minimizing the impact on overall process time while still achieving high interface purity
Solution Approach 2:
The pressure and composition of the gas in the interface gap are dynamically controlled during the process. By optimizing the gas pressure parameters and using reactive gases that quickly form protective atmospheres, the process achieves high interface purity with minimal time penalty
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 effectively reduces contaminants and defects, resulting in optical fibers with lower attenuation and improved quality by eliminating interface irregularities and impurities during the collapsing process.
Implementation Method 1
heating the assembled body to cause the glass tube to collapse on and adhere to the glass core rod
Implementation Method 2
establishing a vacuum pressure in the interface gap
Implementation Method 3
increasing the pressure of the interface gap by flowing oxygen-enriched air through the interface gap for a predetermined time
Data Source
Figure 1
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AI summary
A method of manufacturing an optical fiber preform or an optical fiber is provided. The method includes the steps of: (a) providing a glass tube and a glass core rod; (b) inserting the glass core rod into the glass tube to form an assembled body; (c) heating the assembled body to cause the glass tube to collapse on and adhere to the glass core rod; and (d) treating an interface gap between the glass core rod and the glass tube during heating of at least a portion of the assembled body. Treating of the interface gap involves: (i) establishing a vacuum pressure in the interface gap, (ii) increasing a pressure of the interface gap by a treatment gas through the interface gap for a predetermined time, and (iii) re-establishing a vacuum pressure in the interface gap after the predetermined time has elapsed.