Bending-Resistant Large Core Multimode Fiber Design
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Solution Overview
Problem
Conventional multimode fibers fail to meet high bandwidth requirements and have inadequate bending resistance for local area network applications, where the large number of connectors and couplers, along with the need for expensive laser diodes, increase costs and complexity.
Innovation Solution
A bending-resistant large core diameter high numerical aperture multimode fiber with a trench cladding and specific refractive index profile, designed for easy coupling with LED light sources, is developed, featuring a quartz liner tube and doped glass components, and a manufacturing process that includes plasma-enhanced chemical vapor deposition and outer cladding deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional multimode fibers are used, then the fiber can be used in local area networks, but the bandwidth is insufficient to meet high bandwidth requirements
Solution Approach 1:
The patent changes the refractive index parameters by introducing a trench cladding layer with negative relative refractive index difference, and optimizes the core diameter and numerical aperture parameters to achieve both high bandwidth and bending resistance performance
Solution Approach 2:
The fiber structure uses composite material design with multiple cladding layers (trench cladding and outer cladding) having different refractive index characteristics, combining the benefits of light confinement and bending resistance
2Reliability
If conventional multimode fibers are used, then the fiber structure is simple, but the bending resistance is insufficient for local area network applications
Solution Approach 1:
The cladding layer is segmented into two distinct parts: an inner trench cladding layer with negative refractive index difference and an outer cladding layer with positive refractive index difference, each serving specific functions for bending resistance
Solution Approach 2:
The trench cladding layer is positioned locally adjacent to the core where bending stresses are most significant, providing targeted reinforcement for bending resistance without complicating the entire fiber structure
3Ease of manufacture
If single-mode fibers are used, then the fiber cost is lower, but the overall network cost increases due to expensive laser diodes and connectors
Solution Approach 1:
The patent adopts the multimode fiber approach that copies the successful LED-based network architecture, maintaining compatibility with cost-effective LED light sources and standard multimode connectors rather than transitioning to expensive single-mode laser infrastructure
4Quantity of substance
If multimode fiber has larger core diameter and numerical aperture, then the light gathering capability is improved, but the bending loss increases
Solution Approach 1:
The cladding is divided into trench and outer cladding layers that work together to confine light more effectively, allowing larger core dimensions for better light gathering while compensating for bending-induced light loss
Solution Approach 2:
The composite cladding structure with different refractive index zones creates enhanced light confinement that simultaneously supports large core diameter operation and reduces bending losses
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 fiber achieves high bandwidth and improved bending resistance, reducing macro bending loss and facilitating cost-effective optical power transmission and data transmission in local area networks, while allowing for large-scale production and promotion.
Implementation Method 1
a manufacturing process that includes plasma-enhanced chemical vapor deposition and outer cladding deposition
Data Source
Figure 1~2
Figure 3
AI summary
Disclosed is a bending-resistant large core diameter high numerical aperture multimode fiber, comprising a core and a cladding which coats the core. The radius R1 of the core is 28 to 50 microns; a refractive index profile of the core has a parabola shape; the distribution index α is 1.9 to 2.2, and the maximum relative refractive index difference Δ1%max is 1.9% to 2.5%; and the cladding outside the core comprises an inner cladding and/or a trench cladding, and an outer cladding in sequence from the inside out. The radius R2 of the inner cladding is 28 to 55 microns, and the relative refractive index difference Δ2% is -0.1% to 0.1%. The radius R3 of the trench cladding is 28 to 60 microns, and the relative refractive index difference Δ3% is -0.15% to -0.8%. The bandwidth and the numerical aperture of the bending-resistant large core diameter high numerical aperture multimode fiber are increased, so that the light gathering capacity of the fiber is improved greatly and the multimode fiber is easier to be coupled to an LED light source. The macro bending attached attenuation of the fiber is reduced obviously, the bending resistance performance of the fiber is improved, and the optical power transmission performance is enhanced.