Dual-Trench Multimode Fiber for Low Bend Loss
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Solution Overview
Problem
Multimode optical fibers face challenges in achieving reduced bending losses and high bandwidth while minimizing the cladding effect for high-data rate applications, as existing solutions often result in higher bending losses and lower bandwidth.
Innovation Solution
The optical fiber design incorporates a central core with a graded-index profile, a first depressed trench, an inner cladding, and a second depressed trench, with specific refractive index differences and widths to optimize bandwidth and reduce bending losses, featuring a refractive index profile that minimizes the cladding effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single depressed trench is used between core and cladding, then bandwidth is improved, but bending losses increase
Solution Approach 1:
The single depressed trench is divided into two separate trenches: a first depressed trench between the core and inner cladding, and a second depressed trench between the inner cladding and outer cladding. This segmentation allows independent optimization of bandwidth (by the first trench) and bending loss reduction (by the second trench), resolving the contradiction between improving bandwidth and reducing bending losses.
Solution Approach 2:
The optical fiber structure implements a nested configuration with the core at the center, followed by the first depressed trench, then the inner cladding, then the second depressed trench, and finally the outer cladding. This nested structure of concentric layers with alternating refractive index profiles enables simultaneous achievement of high bandwidth and low bending losses by properly designing each layer's parameters.
2Measurement precision
If core diameter is reduced to increase bandwidth, then bandwidth is improved, but bending losses increase
Solution Approach 1:
Instead of uniformly reducing the core diameter, the invention maintains an optimized core size while introducing localized refractive index modifications through the two depressed trenches. The first trench optimizes modal distribution for bandwidth, while the second trench provides bend insensitivity, allowing the core to maintain its optimal diameter without suffering from increased bending losses.
3Measurement precision
If refractive index difference is increased to reduce cladding effect, then bandwidth is improved, but bending losses increase
Solution Approach 1:
The refractive index differences are localized to specific regions through the two depressed trenches rather than being uniformly distributed. The first trench has a refractive index difference optimized for bandwidth enhancement, while the second trench has a different refractive index difference optimized for reducing the cladding effect and improving bend insensitivity, thus resolving the contradiction.
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 bending losses of less than 0.1 dB for two turns around a 15 mm bend radius and maintains high bandwidth, with a radial offset bandwidth of at least 4,000 MHz·km, effectively addressing the cladding effect and ensuring reliable high-data rate transmission.
Implementation Method 1
An optical fiber (i.e., a glass fiber typically surrounded by one or more coating layers) conventionally includes an optical fiber core, which transmits and/or amplifies an optical signal, and an optical cladding, which confines the optical signal within the core.
Implementation Method 2
The central core is a glass-based central core having an alpha-index profile (i.e., a graded-index profile)
Data Source
AI summary
The present invention embraces an optical fiber that includes a central core having an alpha-index profile with respect to an outer cladding, a first depressed trench, an inner cladding, a second depressed trench, and an outer cladding (e.g., an outer optical cladding). The second depressed trench's volume is typically greater than the first depressed trench's volume. The optical fiber achieves reduced bending losses and a high bandwidth with a reduced cladding effect for high-data rate applications.