Optical Fiber Hydrogen Sensitivity Reduction via Reducing Agent Sintering
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Solution Overview
Problem
Optical fibers are sensitive to hydrogen, leading to increased light attenuation due to non-bridging oxygen defects, which are challenging to passivate efficiently with deuterium treatment, requiring long times and impacting manufacturing efficiency and costs.
Innovation Solution
Treating the optical fiber preform with a reducing agent before consolidation to reduce non-bridging oxygen defect centers, followed by deuterium treatment to further minimize these defects, thereby reducing hydrogen sensitivity and shortening the deuterium treatment time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deuterium treatment is applied to passivate non-bridging oxygen defects, then hydrogen sensitivity is reduced, but treatment time becomes excessively long
Solution Approach 1:
The patent applies preliminary action by treating the preform with a reducing agent (such as carbon monoxide or hydrogen) at high temperature (1000-1500°C) during the consolidation process, before the fiber drawing step. This pre-reduction lowers the initial concentration of non-bridging oxygen defects in the preform, so that subsequent deuterium treatment requires less time to achieve the desired passivation level. The reducing agent treatment creates a more favorable starting condition for the deuterium passivation process.
Solution Approach 2:
The patent employs parameter changes by modifying the oxidation state of the glass matrix through reducing agent treatment. By changing the chemical environment (introducing reducing gases) and controlling temperature parameters during consolidation, the concentration of non-bridging oxygen defects is reduced. This parameter modification enables faster subsequent deuterium treatment while achieving the same hydrogen sensitivity reduction.
2Ease of manufacture
If conventional consolidation process is used, then manufacturing process is simple, but non-bridging oxygen defects remain high requiring long deuterium treatment
Solution Approach 1:
The patent merges two previously separate processes (reducing agent treatment and consolidation) into a single integrated step. The reducing agent is introduced during the consolidation process itself, combining the densification of the preform with the reduction of non-bridging oxygen defects. This integration adds minimal complexity to the consolidation step while achieving dual benefits of structural consolidation and chemical defect reduction.
Solution Approach 2:
The patent modifies the atmospheric parameters during consolidation by introducing reducing gases (such as CO or H2) into the consolidation furnace atmosphere. This parameter change transforms the conventional oxidation environment into a reducing environment, enabling in-situ reduction of non-bridging oxygen defects during the consolidation process without requiring separate treatment steps.
3Productivity
If high concentration of non-bridging oxygen defects is present, then fiber can be drawn quickly, but hydrogen sensitivity increases and requires extended deuterium treatment
Solution Approach 1:
The patent applies preliminary action by reducing non-bridging oxygen defects in the preform before fiber drawing. The reducing agent treatment during consolidation prepares the glass matrix in advance, lowering the defect concentration so that when fiber is drawn and subsequently deuterium treated, the process is more efficient and faster, achieving both productivity and reliability goals.
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 significantly reduces the concentration of non-bridging oxygen defects in the optical fiber, enhancing its hydrogen resistance and reducing manufacturing time and costs by shortening the deuterium treatment process.
Implementation Method 1
The gaseous reducing agent acts to decrease the concentration of oxygen-rich defects in the sintered at least one cladding layer
Implementation Method 2
The deuterium reacts with the non-bridging oxygen defect centers to passivate non-bridging oxygen defects through formation of SiOD and GeOD groups
Implementation Method 3
sintering a preform having a porous chlorine-doped cladding layer
Data Source
Figure 1~2B
Figure 3A~3B
Figure 4
AI summary
The present disclosure is directed to a method of making an optical fiber with improved bend performance, the optical fiber having a core and at least one cladding layer, and a chlorine content in the in the last layer of the at least one cladding layer that is greater than 500 ppm by weight. The fiber is prepared using a mixture of a carrier gas, a gaseous chlorine source material and a gaseous reducing agent during the sintering of the last or outermost layer of the at least one cladding layer. The inclusion of the reducing gas into a mixture of the carrier gas and gaseous chlorine material reduces oxygen-rich defects that results in at least a 20% reduction in TTP during hydrogen aging testing.