Coupled Multicore Fiber Transition Section Design
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Solution Overview
Problem
Conventional coupled multicore optical fibers face challenges in generating sufficient mode coupling when subjected to minimal bending or twisting, leading to increased inter-mode differential mode delay (DMD) due to insufficient mode coupling.
Innovation Solution
The design incorporates a coupled multicore optical fiber with transition sections where mode-field diameters continuously expand from a stationary section to a connected end face, increasing the mode-coupling coefficient and promoting strong mode coupling, even with reduced bending or twisting, thereby delaying DMD accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inter-core coupling strength is appropriately set to reduce differential mode delay, then the mode coupling becomes insufficient when bending or twisting is minimal, but if bending or twisting is increased to promote mode coupling, then the structural integrity and transmission stability deteriorate
Solution Approach 1:
The patent changes the physical parameters of the fiber structure by introducing transition sections with continuously expanding mode-field diameters. This parameter change enables sufficient mode coupling without requiring external bending or twisting, thereby resolving the contradiction between maintaining structural integrity and achieving adequate mode coupling to reduce differential mode delay
Solution Approach 2:
The optical fiber is segmented into stationary sections and transition sections with distinct functional characteristics. The transition sections are specifically designed with expanding mode-field diameters to provide the necessary mode coupling, while the stationary sections maintain standard characteristics for stable transmission, thus resolving the contradiction between different functional requirements
2Reliability
If transition sections with continuously expanding mode-field diameters are introduced to enhance mode coupling, then the fiber structure and manufacturing process become more complex
Solution Approach 1:
The patent applies local quality by introducing transition sections only at specific locations where mode coupling is needed, rather than making the entire fiber structure complex. The transition sections have locally expanded mode-field diameters, while the majority of the fiber maintains simple, standard characteristics, thus resolving the contradiction between enhancing mode coupling and maintaining structural simplicity
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
This configuration enables sufficient mode coupling and reduces DMD accumulation, minimizing transmission loss and computational complexity in MIMO signal processing, enhancing the efficiency of optical transmission systems.
Implementation Method 1
a transition section including the connected end face; and a stationary section disposed adjacently to the transition section along the central axis. Note that the stationary section has respective mode-field diameters of the plurality of cores, substantially constant along the central axis, and the transition section has the respective MFDs of the plurality of cores, continuously expanding from the stationary section to the connected end face
Data Source
AI summary
The present embodiment relates to a CC-MCF capable of generating sufficient mode coupling even with bending or twisting less. The CC-MCF includes two fiber parts having cores mutually directly or indirectly connected, each fiber part having a plurality of cores in which a pair of adjacent cores has a mode-coupling coefficient of 1 (1/m) or more. Each fiber part is provided with a transition section including a fiber end face and a stationary section adjacent to the transition section. In the stationary section, the MFD of each core is substantially constant in a fiber longitudinal direction, and in the transition section, the MFD of each core is continuously expanding from the stationary section to the fiber end face.