12-Core Optical Fiber Structure for Marker-Free, Polarity-Insensitive Splicing
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Solution Overview
Problem
Conventional multi-core optical fibers (MCFs) require markers for core identification and consider polarity during splicing, leading to complex configurations and increased bending losses due to small mode field diameters.
Innovation Solution
A 12-core MCF design with a circular common cladding and specific core arrangements that ensure line and rotational symmetry, allowing marker-free splicing and polarity-insensitive connections, while maintaining a standard coating diameter and suitable for counter propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional MCF designs are used with small mode field diameters, then transmission capacity is improved, but bending losses increase
Solution Approach 1:
The patent applies asymmetry by designing cores with different mode field diameters - inner cores have a first mode field diameter while outer cores have a second mode field diameter that is different from the first. This asymmetric design allows optimization of each core for different functions, enabling high transmission capacity while reducing bending losses through the larger mode field diameter of outer cores
2Measurement precision
If conventional MCF designs require markers for core identification, then core identification accuracy is improved, but device complexity increases
Solution Approach 1:
The patent uses refractive index differences to create distinguishable optical characteristics among cores. The inner cores and outer cores have different mode field diameters which create different optical field distributions, allowing core identification through optical measurement without requiring physical markers or complex configuration systems
3Reliability
If conventional MCF designs consider polarity during splicing, then connection reliability is improved, but ease of operation decreases
Solution Approach 1:
The asymmetric core design with different mode field diameters creates inherently distinguishable core characteristics. This allows splicing operations to identify and connect corresponding cores without needing to consider polarity, as the different optical characteristics provide natural identification. The symmetry in optical performance is maintained while eliminating polarity considerations from the splicing process
Data Source
AI summary
The MCF of the present disclosure suppresses XT and leakage loss at 1.565 μm or 1.625 μm for bidirectional communication. The MCF comprises 12 core units each including a core and a depressed layer, a common cladding, and a resin coating. The units are arranged so that no adjacent relationship is established between cores each having an adjacent relationship with a specific core selected from the units, and are arranged so that centers of the units are line symmetric with a symmetry axis intersecting with the central axis and passing through none of the centers of the units. The resin coating's diameter is 250±15 μm, an effective area at 1.550 μm is 70 μm2 or more, and a 22 m-length cable cutoff wavelength is 1.530 μm or less. A center-to-center interval between adjacent cores, a shortest distance from the core center to the cladding interface, and a cladding's diameter satisfy specific conditions.