Single-Mode Optical Fiber Profile for Low O- and E-Band Dispersion
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Solution Overview
Problem
Existing single-mode optical fibers, such as G.652 and G.657, are unable to effectively operate in the O and E wavelength bands due to high chromatic dispersion, limiting their use in Metro Wave Division Multiplexing systems and failing to meet the expanding data transmission demands of 5G commercialization.
Innovation Solution
A single-mode optical fiber design with a core and cladding structure optimized for refractive index profiles, featuring a core with specific refractive index variations and cladding layers, allowing for chromatic dispersion between -9 and +3 ps/(nm.km) in the 1268 to 1375nm range, matching the requirements of Metro Wave Division Multiplexing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If standard single-mode optical fibers (G.652, G.657) are used, then the fibers have good optical performance in conventional bands, but they cannot effectively operate in O and E wavelength bands due to high chromatic dispersion
Solution Approach 1:
The patent modifies the refractive index parameters of the optical fiber by introducing a second cladding layer with specific refractive index characteristics. This layer has a refractive index lower than the first cladding layer, creating a tailored refractive index profile that shifts the zero dispersion wavelength to enable effective operation in both O and E bands while maintaining low chromatic dispersion
Solution Approach 2:
The optical fiber employs a composite cladding structure with two distinct layers having different refractive indices. The first cladding layer and second cladding layer form a composite structure that works together to achieve the desired chromatic dispersion characteristics across multiple wavelength bands, combining the advantages of different refractive index materials
2Productivity
If the chromatic dispersion is reduced for O and E band operation, then the fiber can support Metro Wave Division Multiplexing systems, but the fiber structure becomes more complex with additional cladding layers
Solution Approach 1:
The cladding is segmented into two distinct layers, each with specific refractive index characteristics. The first cladding layer provides a transition zone, while the second cladding layer with lower refractive index creates the necessary optical conditions for reduced chromatic dispersion. This segmentation allows precise control over the refractive index profile to achieve multi-band operation
Solution Approach 2:
The second cladding layer is positioned at a specific radial distance from the core, creating a localized region with lower refractive index. This local modification of the refractive index profile at a specific location (between the first cladding layer and the outer boundary) enables the fiber to achieve low chromatic dispersion in the O and E bands without affecting other structural properties
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 fiber maintains similar optical performance to G.652 and G.657 fibers while enabling operation in both O and E wavelength bands, doubling wavelength channels and supporting 25Gb/s transceivers, with reduced wavelength spacing and low bend losses.
Implementation Method 1
a core having a refractive index n, wherein the core comprises a region in which the value of n decreases from a value n0 at a radius r0, to a value n2 at a radius r1; and a cladding having a refractive index n'
Implementation Method 2
the refractive-index profile of the core and cladding is defined by the following profile parameters
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a single-mode optical fiber comprising: - a core (10) having a refractive index n, wherein the core comprises a region in which the value of n decreases from a value n0, to a value n2; and - a cladding (20) comprising: ∘ a first layer of cladding (21) wherein the refractive index is n2; and ∘ a second layer of cladding (22) wherein the refractive index is n3, lower than n2; ∘ a third layer of cladding (23) wherein the refractive index is n4, higher than n3; wherein the core radius r1 is comprised between 2.5 µm and 5.5 µm; and wherein a refractive-index difference Δn0 = n0 - n4 is higher than 5.8 × 10-3; and wherein a refractive-index difference Δn2 = n2 - n4 is between 1 × 10-3 and 2.5 × 10-3; and wherein a refractive-index difference Δn3 = n3 - n4 is lower than 0.