Multimode Optical Fiber Trench Structure for Bandwidth Stability
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Solution Overview
Problem
Conventional multimode optical fibers (MMFs) face significant challenges in maintaining bandwidth stability due to slight variations in the α-value of the refractive index profile, leading to increased intermodal dispersion and bandwidth degradation, particularly in meeting OM3 and OM4 standards for fast communication networks.
Innovation Solution
The development of Graded Index (GI-MMF) and Bend-Insensitive MultiMode (BI-MMF) optical fibers with a trench part of lower refractive index between the core and cladding, which attenuates light propagating in the outside core region, reducing the dependence on the refractive index profile shape and maintaining wide-bandwidth transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the α-value of the refractive index profile is optimized for wide-band transmission, then bandwidth is improved, but manufacturing precision requirements become extremely strict leading to low production yield
Solution Approach 1:
The patent introduces a trench structure with specific refractive index characteristics located at a particular region between the core and cladding. This local structural modification creates different functional zones: the trench region suppresses higher-order modes while the core region maintains optimized light propagation. By making the refractive index profile non-uniform with a distinct trench zone, the system achieves bandwidth enhancement without requiring extremely precise control of the overall α-value, thus resolving the contradiction between reliability and manufacturing precision
Solution Approach 2:
The patent modifies the refractive index distribution by introducing a trench with refractive index n3 that is lower than both the core (n1) and cladding (n2). This parameter change in the refractive index profile fundamentally alters the mode propagation characteristics. The trench structure changes the effective refractive index experienced by different modes, suppressing higher-order modes and reducing intermodal dispersion. This parameter modification allows the system to achieve wide-band transmission with more relaxed α-value tolerances, resolving the manufacturing precision issue
2Reliability
If the refractive index profile shape is optimized for fundamental mode transmission, then bandwidth is improved, but intermodal dispersion increases when α-value varies
Solution Approach 1:
The trench structure is designed to preemptively counteract the harmful effects of α-value variations before they can degrade bandwidth. By introducing the trench with its specific refractive index n3 < n2, the system pre-establishes a structural feature that actively suppresses higher-order modes and reduces intermodal dispersion. This preliminary structural configuration compensates for potential α-value deviations, maintaining bandwidth stability without requiring extremely precise α-value control during manufacturing
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 proposed MMF structure effectively suppresses bandwidth degradation by attenuating light in the outside core region, ensuring stable wide-band multimode optical transmission and easier compliance with OM3 and OM4 standards, even with deviations in the α-value, thereby enhancing production yield and communication capacity.
Implementation Method 1
a trench part provided between the core and the cladding... which attenuates light propagating in the outside core region
Implementation Method 2
the core has an outer diameter 2a and has an α-power refractive index profile... refractive index profile of a core in a MMF (indicating refractive indices at respective portions)
Data Source
AI summary
An embodiment of the invention relates to a MMF with a structure for enabling stable manufacture of the MMF suitable for wide-band multimode optical transmission, for realizing faster short-haul information transmission than before. In the MMF, when an input position of a DMD measurement pulse on an input end face is represented by a distance r from a center of a core with a radius a, a power of the DMD measurement pulse on an output end face with the input position r of the DMD measurement pulse being 0.8a is not more than 70% of a power of the DMD measurement pulse on the output end face with the input position r of the DMD measurement pulse being 0.