Optical Fiber With Trench Layer For Low Bending Loss
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Solution Overview
Problem
Existing optical fibers with three-layer structures face challenges in achieving low bending loss, low transmission loss, and high manufacturability due to the need for precise control of refractive-index differences and dopant usage, which can lead to increased manufacturing errors and costs.
Innovation Solution
An optical fiber design featuring a central core, intermediate, and cladding layers made of silica-based glass with specific refractive-index differences (Δ1, Δ2, Δ3) optimized for low bending loss, where Δ1>Δ2>Δ3, and controlled dopant usage to minimize manufacturing errors and costs, while maintaining low transmission loss and high mode field diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refractive-index difference parameters (Δ1, Δ2, Δ3) are precisely controlled to achieve low bending loss, then the bending loss characteristics are improved, but the manufacturing precision requirements increase and manufacturing errors increase
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive-index difference parameters to specific ranges: 0.34% ≤ Δ1 ≤ 0.37%, 0.1% ≤ |Δ3| ≤ 0.25%, and Δ1×|Δ3| ≤ 0.08%². These parameter specifications balance the need for low bending loss with manufacturability, resolving the contradiction between reliability and manufacturing precision by defining acceptable parameter windows rather than requiring exact values.
2Reliability
If dopant usage is increased to optimize refractive-index differences, then the optical characteristics are improved, but the manufacturing costs increase and manufacturing errors increase
Solution Approach 1:
The patent optimizes dopant usage by specifying precise refractive-index difference ranges that achieve the desired optical characteristics without excessive dopant concentrations. By defining Δ1, Δ2, and Δ3 within specific boundaries, the patent reduces manufacturing costs and errors while maintaining optical performance.
Solution Approach 2:
The patent uses composite material composition in the three-layer structure (central core portion, intermediate layer, and trench layer) with different dopant concentrations. This composite approach allows each layer to contribute differently to the overall optical performance, achieving low bending loss and transmission loss through material composition optimization rather than uniform high dopant usage throughout.
3Reliability
If the three-layer structure with trench is implemented to achieve low bending loss, then the bending loss characteristics are improved, but the device complexity increases
Solution Approach 1:
The patent divides the optical fiber into three distinct layers: a central core portion, an intermediate layer, and a trench layer. This segmentation allows each layer to serve a specific function in controlling light propagation and reducing bending loss, while the modular structure makes the complex design more manageable in terms of manufacturing and quality control.
Solution Approach 2:
The patent applies local quality by assigning different refractive-index characteristics to different regions: the central core portion has Δ1, the intermediate layer has Δ2, and the trench layer has Δ3. Each region is optimized for its specific function, with the trench layer providing negative refractive-index difference (Δ3 < 0) to confine light and reduce bending loss, while the other layers provide positive refractive-index differences. This localized optimization achieves low bending loss without requiring uniform complexity throughout the entire 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 optimized optical fiber achieves low transmission loss (<0.195 dB/km) and improved manufacturability by reducing dopant usage and manufacturing errors, while meeting standards for low bending loss and mode field diameter, making it suitable for various communication applications.
Implementation Method 1
an optical fiber having a three-layer structure including a trench structure has been disclosed... relationships Δ1>Δ2>Δ3 and 0>Δ3 are satisfied
Data Source
AI summary
An optical fiber includes: a central core portion; an intermediate layer; a trench layer; and a cladding portion. Further, relationships Δ1>Δ2>Δ3 and 0>Δ3 are satisfied, where Δ1, Δ2, and Δ3 are a relative refractive-index difference of the central core portion, the intermediate layer, and the trench layer, respectively, with respect to the cladding portion, Δ1 is equal to or larger than 0.34% and equal to or smaller than 0.37%, |Δ3| is equal to or larger than 0.1% and equal to or smaller than 0.25%, Δ1×|Δ3| is equal to or smaller than 0.08%2, a mode field diameter at a wavelength of 1310 nm is equal to or larger than 8.8 μm, and a transmission loss at a wavelength of 1550 nm is equal to or smaller than 0.195 dB/km.