Multi-Core Optical Amplifying Fiber for Low-Crosstalk Cladding Pumping
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Solution Overview
Problem
Multi-core optical amplifying fibers need improved excitation efficiency to enhance communication capacity and reduce power consumption in optical amplifiers.
Innovation Solution
A multi-core optical amplifying fiber with specific refractive index profiles and core-to-core distances to minimize inter-core crosstalk, combined with a cladding pumping system, enhances excitation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple single-core optical fiber amplifiers are used to amplify multiple wavelengths, then wavelength division multiplexing communication is enabled, but the number of amplifiers increases and device complexity increases
Solution Approach 1:
The patent combines multiple single-core optical fiber amplifiers into a single multicore optical fiber amplifier. The amplifier includes a multicore optical fiber with multiple cores, where each core can independently amplify different wavelength signals. This merging approach reduces the total number of amplifier devices while maintaining the capability to handle multiple wavelengths through wavelength division multiplexing.
Solution Approach 2:
The multicore optical fiber is segmented into multiple independent cores within a single fiber structure. Each core functions as an independent amplification channel, allowing simultaneous amplification of different wavelength signals. This segmentation enables a single amplifier device to perform the function of multiple single-core amplifiers.
2Quantity of substance
If the core interval of the multicore optical fiber is reduced to increase channel density, then the number of cores per fiber increases, but coupling between adjacent cores increases causing signal interference
Solution Approach 1:
The patent applies local quality by designing different refractive index profiles for different regions of the multicore fiber. The cladding regions between adjacent cores have optimized refractive indices that create optical isolation, while the core regions maintain high refractive indices for signal confinement. This local differentiation of optical properties reduces coupling interference between adjacent cores while allowing high core density.
Solution Approach 2:
The multicore optical fiber uses composite material structures with multiple layers having different refractive indices. The fiber comprises cores with high refractive index surrounded by cladding with lower refractive index, and intermediate isolation layers with specifically designed refractive indices. This composite structure enables tight packing of cores while maintaining optical isolation through the layered material design.
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 solution achieves improved excitation efficiency and reduced inter-core crosstalk, leading to increased optical power density and reduced power consumption in multi-core optical fiber amplifiers.
Implementation Method 1
amplifies a signal in an optical domain without being converted into an electrical signal
Implementation Method 2
an amplifier including a multicore optical fiber and a gain medium, the gain medium including erbium
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A multi-core optical amplifying fiber includes a plurality of core portions doped with a rare-earth element, an inner cladding portion surrounding the core portions and having a refractive index lower than the maximum refractive index of the core portions, and an outer cladding portion surrounding the inner cladding portion and having a refractive index lower than the refractive index of the inner cladding portion. A mode field diameter of each of the core portions at a wavelength at which the rare-earth element performs optical amplification is 5 um to 11 um. A relative refractive-index difference of the maximum refractive index of each of the core portions with respect to the inner cladding portion is 0.35% to 2%. A core-to-core distance between the core portions on a section perpendicular to the longitudinal direction is set such that total inter-core crosstalk is -40 dB/100 m or lower in an optical amplification wavelength band. A cladding thickness is smaller than a value obtained by adding the mode field diameter to the minimum value of the core-to-core distance.