Multimode Optical Fiber Trench OH Control
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Solution Overview
Problem
Multimode optical fibers face transmission loss and bandwidth limitations due to residual stress and refractive index variations, which affect their performance in short-haul information transmission, particularly in meeting OM3 and OM4 standards.
Innovation Solution
A Graded Index (GI) type multimode optical fiber with a core doped with GeO2 and a trench part doped with fluorine, featuring a specific OH group concentration distribution to control refractive index and reduce residual stress, enhancing bend resistance and bandwidth performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the core is doped with GeO2 to form a refractive index profile, then the refractive index profile shape is improved, but residual stress causes variation in the refractive index profile
Solution Approach 1:
A trench part with lower refractive index is introduced as an intermediary layer between the core and cladding. This trench part acts as a mediator that suppresses residual stress and prevents its influence from distorting the refractive index profile of the core, thereby maintaining both the shape accuracy and stability of the profile.
Solution Approach 2:
The trench part is positioned specifically at the boundary region between the core and cladding, where it locally suppresses residual stress. This localized approach allows the core to maintain its refractive index profile shape while the trench part handles the stress management function at the critical interface.
2Stability of the object's composition
If the trench part is added to suppress residual stress, then refractive index profile stability is improved, but the structure becomes more complex
Solution Approach 1:
Instead of making the entire fiber structure complex, the trench part is introduced only as a localized layer at the core-cladding boundary. This minimal addition provides the necessary stress suppression while keeping the overall structure relatively simple and maintaining manufacturability.
3Stability of the object's composition
If OH group concentration is controlled in the trench part, then residual stress is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The OH group concentration control is applied specifically in the trench part rather than uniformly throughout the entire fiber. This localized approach allows residual stress suppression at the critical boundary region while reducing the overall manufacturing precision requirements compared to controlling OH groups in the entire fiber structure.
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 solution stabilizes the refractive index profile, reduces residual stress, and improves bandwidth, meeting OM3 and OM4 standards by suppressing higher-order mode attenuation and increasing bandwidth at 850 nm and 1300 nm wavelengths.
Implementation Method 1
a core (111) with an outside diameter 2a extending along a predetermined axis and doped with GeO2
Implementation Method 2
a refractive index profile conforming to an α-profile
Implementation Method 3
The trench part is a glass region with an outside diameter 2b surrounding an outer peripheral surface of the core and is doped with fluorine
Implementation Method 4
an OH (hydroxyl) group concentration distribution is controlled to a specific shape
Data Source
AI summary
An embodiment of the invention relates to a BI-MMF with OH group concentrations controlled along a radial direction. In the BI-MMF, an OH group concentration distribution along the radial direction has a shape in which a concentration peak is located in a concentration control interval provided between an outer periphery of a core and a trench part, including an interface between the core and trench part.