Multi-Core Fiber Raman Amplification Crosstalk Control
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Solution Overview
Problem
In optical transmission systems using multi-core fibers, reception cross-talk noise deviates from designed values due to transmission loss differences between cores, making it challenging to satisfy modulation system requirements.
Innovation Solution
The system adjusts the intensity ratio of bidirectional Raman amplification excitation light to curb deviations in reception cross-talk noise, ensuring it meets the required values by using both forward and backward excitation light sources to balance inter-core loss differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If distributed Raman amplification is applied to amplify optical signals in MCF, then reception XT can be curbed to required values, but inter-core loss differences cause deviation in reception XT performance
Solution Approach 1:
The patent changes the intensity ratio parameter of bidirectional excitation lights to compensate for inter-core loss differences. By adjusting the intensity ratio within a specific range based on the loss difference, the reception XT is maintained within required values despite manufacturing variations in core losses.
Solution Approach 2:
The patent introduces asymmetric excitation light intensities in bidirectional Raman amplification to counterbalance the asymmetric loss characteristics of different cores. The excitation light intensity ratio is set differently for forward and backward directions to compensate for the inter-core loss differences.
2Power
If bidirectional Raman amplification with fixed intensity ratio is used, then amplification can be achieved, but reception XT deviation occurs due to inter-core loss differences
Solution Approach 1:
The patent makes the excitation light intensity ratio dynamic rather than fixed. The ratio is adjusted according to the measured or estimated inter-core loss differences, allowing the system to adapt to varying loss conditions and maintain consistent reception XT performance across different cores.
Solution Approach 2:
The intensity ratio of excitation lights is changed based on inter-core loss characteristics. By optimizing this parameter within a specific range, the system achieves both adequate signal amplification and consistent reception XT performance across cores with different loss values.
3Reliability
If inter-core distance and core structure are designed to satisfy XT requirements, then XT performance can be ensured under ideal conditions, but production and connection quality deviations cause reception XT to exceed required values
Solution Approach 1:
The patent applies beforehand cushioning by pre-compensating for potential loss variations through optimized bidirectional Raman amplification. The excitation light intensity ratio is designed to compensate for expected inter-core loss differences, cushioning against the impact of production and connection quality deviations before they affect reception XT.
Solution Approach 2:
The patent uses parameter optimization of excitation light intensities to compensate for manufacturing tolerances. By adjusting the intensity ratio parameter, the system maintains XT performance within required values even when actual core losses deviate from ideal design values due to production and connection variations.
Data Source
AI summary
An object of the present invention is to provide an optical transmission system capable of satisfying XT required by a modulation system even if there is an inter-core loss difference in an MCF.An optical transmission system of the present invention includes a multi-core optical fiber having a plurality of core regions and having different losses between at least two cores, a forward excitation light source and a multiplexing unit for allowing Raman amplification excitation light to be incident on each core of the multi-core optical fiber in the same direction as signal light, and a backward excitation light source and a multiplexing unit for allowing Raman amplification excitation light to be incident on each core of the multi-core optical fiber in a direction opposite to the signal light, wherein an intensity ratio of the forward excitation light to the backward excitation light is controlled (a ratio of power of excitation light is set to a predetermined value) such that crosstalk (XT) fluctuation between cores is reduced.