Dispersion Map Shifting for Mixed Coherent Channels
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Solution Overview
Problem
Existing fiber-optic communication networks face challenges in transmitting coherent and non-coherent optical channels over long distances due to dispersion issues, where conventional dispersion compensation designs are optimized for non-coherent channels, leading to degraded signal quality for coherent channels.
Innovation Solution
Introducing a dispersive element to shift the dispersion map of coherent optical channels differently from non-coherent channels, allowing them to be transmitted effectively over the same optical link by moving the zero dispersion point and maintaining signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dispersion compensation designs are used, then non-coherent channels are optimized for long-distance transmission, but coherent channels experience degraded signal quality
Solution Approach 1:
The optical link is segmented into different dispersion map regions: a first dispersion map for non-coherent channels and a second dispersion map for coherent channels. This segmentation allows each channel type to operate in its optimal dispersion regime, resolving the contradiction between optimizing for non-coherent channels while maintaining coherent channel performance
Solution Approach 2:
Different dispersion map characteristics are applied locally to different channel types. Non-coherent channels receive a dispersion map optimized for direct detection with accumulated dispersion near zero, while coherent channels receive a dispersion map that allows larger accumulated dispersion values. This local quality differentiation enables simultaneous optimization for both channel types
2Measurement precision
If the dispersion map is optimized for non-coherent channels, then direct detection works well, but coherent detection suffers from degraded signal quality
Solution Approach 1:
The system performs preliminary dispersion management by establishing separate dispersion maps before signal detection. The first dispersion map is prepared for non-coherent channels with accumulated dispersion near zero, while the second dispersion map is prepared for coherent channels with larger accumulated dispersion. This preliminary action ensures both channel types arrive at their respective detectors in optimal condition
Solution Approach 2:
Instead of forcing coherent channels to adapt to the non-coherent channel's dispersion map, the invention inverts the approach by allowing coherent channels to operate with larger accumulated dispersion and using electronic dispersion compensation in the coherent receiver. This inversion leverages the strengths of coherent detection rather than constraining it to match non-coherent requirements
3Ease of operation
If accumulated dispersion is kept near zero for non-coherent channels, then direct detection is effective, but coherent channels cannot utilize electronic dispersion compensation effectively
Solution Approach 1:
The dispersion management approach is segmented into two distinct strategies: one for non-coherent channels that maintains accumulated dispersion near zero for optimal direct detection, and another for coherent channels that allows larger accumulated dispersion values. This segmentation enables each detection method to operate in its optimal regime without compromise
Solution Approach 2:
The optical link is designed with universal dispersion map compatibility that supports both direct detection and coherent detection modes. By implementing separate dispersion maps that can coexist in the same link, the system achieves multi-functionality where the infrastructure can serve both detection types effectively, with each channel type utilizing its optimal detection method
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
Enables the simultaneous transmission of coherent and non-coherent optical channels over long distances with improved signal quality, as the dispersion map is optimized for both channel types, reducing the dependency on accumulated dispersion and enhancing detection accuracy.
Implementation Method 1
All optical fiber is dispersive wherein the dispersion value varies with optical wavelength... a dispersive element introduces dispersion into the coherent optical wavelength channel set and/or into the non-coherent optical wavelength channel set
Data Source
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AI summary
An optical introduction node (300) is disclosed, configured to mix one or more coherent optical wavelength channels (301G, 301H) with one or more non-coherent optical wavelength channels (301A-301F). The optical introduction node (300) comprises a dispersive element (302A, 302B) that introduces dispersion into the one or more coherent optical wavelength channels (301G, 301H) and/or into the one or more non-coherent optical wavelength channels (301A-301F) such that the dispersion map of the one or more coherent optical wavelength channels (301G, 301H) is shifted from the dispersion map of the one or more non-coherent optical wavelength channels (301A-301F).