Graded-Index Multimode Fiber With Triangular Trench for Bend-Loss Reduction
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Solution Overview
Problem
Existing multimode optical fibers face challenges in achieving improved bend performance without compromising other performance characteristics and are difficult to manufacture with simpler processes, leading to higher production costs.
Innovation Solution
A multimode optical fiber design featuring a core with a graded index and a trench region, including a transition region, where the trench region has a triangular relative refractive index profile with a continuously decreasing relative refractive index delta percent, and specific alpha values for the core and transition regions, optimizing the fiber for high modal bandwidth and bend resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluorine-doped index trench is used to improve bend performance, then bend insensitivity is improved, but manufacturing complexity and production cost increase
Solution Approach 1:
The patent extracts the fluorine doping requirement from the trench design, replacing it with a silicon-doped trench that achieves similar bend performance through a different mechanism. This simplifies manufacturing by eliminating the need for fluorine doping processes while maintaining the essential function of the trench in guiding light and reducing bend loss.
Solution Approach 2:
The patent changes the chemical composition parameters of the trench region, transitioning from fluorine-doped (traditional) to silicon-doped (innovative). This parameter change maintains the refractive index depression function necessary for bend performance while using more commercially available and simpler doping processes.
2Reliability
If complex trench designs are used to improve bend performance, then bend insensitivity is improved, but manufacturing simplicity deteriorates
Solution Approach 1:
The patent applies local quality by creating a trench with a specific triangular refractive index profile only in the regions where it is most needed for bend performance, rather than uniformly complex designs throughout. The trench depth and width vary locally to optimize bend insensitivity while keeping the overall structure manufacturable with standard processes.
3Ease of manufacture
If traditional trench designs are used, then manufacturing process is simpler, but bend performance is compromised
Solution Approach 1:
The patent uses composite material principles by combining silicon doping with the trench structure, creating a composite region that has both the mechanical properties needed for standard manufacturing and the optical properties needed for superior bend performance. The silicon-doped trench acts as a composite structure that integrates both manufacturing simplicity and performance enhancement.
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 design achieves a minimum calculated effective modal bandwidth of greater than 4.0 GHz-km and overfilled bandwidth of greater than 3.0 GHz-km at 850 nm, with low bend loss, enhancing fiber performance and manufacturability.
Implementation Method 1
a core, a trench region, and a transition region disposed between the core and the trench region
Implementation Method 2
the trench region may include a triangular relative refractive index profile
Data Source
AI summary
A multimode optical fiber may include a core and a trench region. The core may include a radius R1 that is greater than or equal to 23 μm and less than or equal to 27 μm and a graded index having an alpha value that is greater than or equal to 1.9 and less than or equal to 2.2. The trench region may include a triangular relative refractive index profile. The trench region may include at least one portion within which a relative refractive index delta percent of the trench region decreases with increasing radius. The trench region may include a trench volume V3 ranging from −100%-microns2 to −170%-microns2.