Achromatic Variable Ratio Couplers for Broadband FTTH Splitting
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Solution Overview
Problem
Existing fiber optic couplers in FTTH networks are fixed ratio, requiring multiple SKUs, increasing manufacturing and inventory costs, and necessitate high skill levels for installation, which is inefficient and costly.
Innovation Solution
Achromatic variable ratio couplers with a glass tube and optical waveguides having specific refractive index differences and taper lengths, allowing for manual adjustment of split ratios and operation across broad bandwidths, reducing the need for multiple couplers and simplifying installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed ratio couplers are used to manage power splitting in FTTH networks, then the split ratio is stable and reliable, but multiple SKUs are required increasing manufacturing and inventory costs, and high skill levels are needed for installation
Solution Approach 1:
The patent applies universality by designing a single variable ratio coupler that can provide multiple split ratios (e.g., 98/2, 90/10, 80/20, 70/30, 50/50) through mechanical adjustment. This eliminates the need for multiple fixed ratio coupler SKUs, as one universal device replaces many specialized ones. The coupler maintains reliable power splitting while reducing inventory complexity and manufacturing costs.
Solution Approach 2:
The patent applies dynamics by making the split ratio adjustable rather than fixed. The variable ratio coupler allows technicians to mechanically adjust the coupling ratio in the field to match network requirements. This dynamic capability replaces static fixed ratio devices, enabling a single SKU to serve multiple functions while maintaining installation reliability.
2Ease of manufacture
If fixed ratio couplers are used, then manufacturing is straightforward, but inventory costs increase due to multiple SKUs and technicians must carry many different couplers
Solution Approach 1:
The variable ratio coupler serves as a universal device that replaces multiple fixed ratio couplers in inventory. By providing continuous or discrete adjustable ratios from a single device type, manufacturers need to produce and stock only one SKU instead of many, significantly reducing inventory variety and associated costs while maintaining ease of manufacture.
3Ease of operation
If fixed ratio couplers are used, then installation is simple with standardized procedures, but high skill levels are required and installation time increases
Solution Approach 1:
The variable ratio coupler allows technicians to adjust the split ratio in the field to match specific network requirements without requiring precise pre-selection of fixed ratios. This dynamic adjustment capability simplifies installation procedures and reduces the need for high skill levels, as technicians can optimize performance on-site rather than requiring perfect initial selection. The mechanical adjustment is straightforward and reduces installation time.
4Reliability
If conventional FBT couplers are used, then manufacturing is reliable, but wavelength dependence limits broadband performance
Solution Approach 1:
The patent applies parameter changes by optimizing the physical and optical parameters of the fused biconical taper structure to achieve broadband performance. Specifically, the coupler design incorporates a long taper length and optimized waist dimensions that reduce wavelength dependence of the coupling ratio. This allows the same reliable FBT manufacturing process to produce couplers that perform consistently across broad wavelength ranges (e.g., 1260-1650 nm), enhancing adaptability to different optical wavelengths and broadband applications.
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
Enables flexible network design with a single SKU, lowering manufacturing and inventory costs, and facilitating easy installation with reliable manual adjustment, outperforming conventional couplers in terms of cost-effectiveness and flexibility.
Implementation Method 1
each of the first optical waveguide and the second optical waveguide comprising a core surrounded by a cladding. A refractive index of the cladding is less than a refractive index of the core
Implementation Method 2
A coupling region is present between the first optical waveguide and the second optical waveguide within the tapered region
Data Source
AI summary
In one embodiment, a coupler includes a glass tube having a refractive index n3 and a passageway, a first optical waveguide and a second optical waveguide positioned within the passageway, each of the first optical waveguide and the second optical waveguide comprising a core surrounded by a cladding. The glass tube further includes a tapered region having a taper length. A coupling region is present between the first optical waveguide and the second optical waveguide within the tapered region. A refractive index of the cladding is less than a refractive index of the core, and a lowest refractive index of the cladding of the first optical waveguide and the second optical waveguide is n2. Additionally, n3 is lower than n2 such that a value of Δ2-3 is 0.07%≤Δ2-3≤0.125, where Δ2-3 equals (n22−n32)/2n22.