Dual-Core Optical Fiber with Depressed Cladding for Low Cross-Talk
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Solution Overview
Problem
The standard geometry of optical fibers restricts the maximum density of optical input and output connections for photonic chips, making it inefficient and costly to increase core density using multicore fibers.
Innovation Solution
A dual-core optical fiber design with a common cladding radius of less than or equal to 45 μm and a waveguide-to-waveguide separation distance of at least 30 μm, incorporating a depressed cladding region to achieve low cross-talk and high core density, allowing for increased packing density in optical fiber cables and interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If standard geometry optical fibers are used, then connections between optical fiber cables and telecommunication devices are well-suited, but the maximum density of optical input and output connections for photonic chips is severely restricted
Solution Approach 1:
The invention divides the optical fiber into multiple cores within a single fiber structure, creating multicore optical fibers with 2, 4, 6, 8, or more cores. This segmentation allows multiple optical signal lines to be transmitted through one fiber, thereby increasing core density while maintaining standard geometry compatibility for external connections.
Solution Approach 2:
Multiple core regions are nested within a common cladding structure, with each core surrounded by its own inner cladding. The cores are arranged in a nested configuration within the shared outer cladding, maximizing spatial utilization and increasing the number of cores that can fit within the standard fiber geometry.
2Quantity of substance
If multicore optical fibers with standard geometry are produced to increase core density, then more transmission paths are provided, but production becomes inefficient and costly
Solution Approach 1:
The invention uses a common cladding structure that serves multiple cores simultaneously, rather than creating separate fibers for each core. This universal cladding design simplifies the manufacturing process, reduces material requirements, and lowers production costs while achieving high core density.
Solution Approach 2:
Multiple core regions and their respective inner claddings are merged into a single common cladding structure. This combining approach allows all cores to be manufactured as an integrated unit rather than assembling multiple separate fibers, significantly improving production efficiency and reducing costs.
3Quantity of substance
If cores are placed closer together to increase density, then core density increases, but cross-talk between waveguides increases
Solution Approach 1:
The invention implements different refractive index characteristics in different regions of the fiber structure. Each core has a higher refractive index than its surrounding inner cladding, which in turn has different refractive index properties than the common cladding. This local quality differentiation creates optical isolation between adjacent cores, reducing cross-talk while allowing close spacing for high density.
Solution Approach 2:
The fiber structure employs composite material design with multiple regions having different refractive indices: core regions with doping concentrations optimized for light guidance, inner cladding regions providing optical isolation, and a common cladding combining multiple functions. This composite structure enables close core spacing while maintaining low cross-talk through refractive index engineering.
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 dual-core optical fiber configuration significantly enhances core density, reducing fiber pitches and facilitating denser interconnections between network components while maintaining low cross-talk, thus improving the efficiency and cost-effectiveness of optical communication systems.
Implementation Method 1
a first depressed cladding region circumferentially surrounding and contacting the core region of the first waveguide and having a first refractive index that is less than a refractive index of the common cladding; a second depressed cladding region circumferentially surrounding and contacting the core region of the second waveguide and having a second refractive index that is less than a refractive index of the common cladding
Data Source
AI summary
A dual-core optical fiber include a first waveguide comprising a first core longitudinal centreline and a second waveguide comprising a second core longitudinal centreline. The first and second waveguides extend through a common cladding through comprising a longitudinal centerline and an outer radius R4 that is less than or equal to 45 μm. The first core longitudinal centerline and the second core longitudinal centerline are separated from one another by a waveguide-to-waveguide separation distance that is greater than or equal to 30 μm. A cross-talk between the first and second waveguides is less than or equal to −40 dB at 1310 nm, as measured over a length of 100 km of the dual-core optical fiber.