Optical Power Equalization in Flex ROADM Systems

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Solution Overview

Problem

In Flex ROADM systems, existing technologies fail to effectively perform optical power equalization among optical channels and sub-carriers, leading to issues like signal power imbalance and reduced signal-to-noise ratio, especially in flexible grid environments beyond 100G transmission.

Innovation Solution

An optical power equalization method and apparatus that monitors optical power and signal-to-noise ratio, using backward and forward control to adjust optical power across channels and sub-carriers, ensuring dynamic equalization based on monitoring results and target values, with components like wavelength selective switches and optical amplifiers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If flexible grid technology is adopted to enable variable channel widths for different modulation codes and speed rates, then adaptability of the optical network is improved, but optical power equalization becomes more complex due to varying channel configurations and sub-carrier compositions

Engineering Contradiction:
Improveadaptability of optical networkVSAvoidcomplexity of optical power equalization
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the optical power equalization process into two distinct levels: channel-level equalization (addressing power differences between different optical channels) and sub-carrier-level equalization (addressing power differences among sub-carriers within each channel). This segmentation allows the system to handle flexible grid configurations at each level independently, resolving the complexity arising from variable channel widths and modulation schemes.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic optical power equalization by continuously monitoring optical power levels of channels and sub-carriers, and adjusting equalization parameters in real-time based on actual system conditions. This dynamic approach enables the system to adapt to changing flexible grid configurations, modulation types, and speed rates while maintaining optimal power distribution.

Inventive Principle:
Principle #15Dynamics

2Reliability

If optical power equalization is performed among all sub-carriers in each channel, then signal quality is improved, but system complexity and control difficulty increase significantly

Engineering Contradiction:
Improvesignal qualityVSAvoidcomplexity of equalization control
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides sub-carrier power equalization into channel-specific groups, where each channel's sub-carriers are equalized independently based on that channel's specific modulation scheme and speed rate requirements. This segmented approach reduces control complexity compared to a unified system-wide equalization, while still achieving optimal signal quality for each channel.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements selective sub-carrier equalization, applying equalization to only those sub-carriers that require it based on their specific power deviations, rather than uniformly equalizing all sub-carriers in the system. This partial action approach reduces unnecessary control operations while maintaining signal quality where needed.

Inventive Principle:
Principle #16Partial or excessive action

3Stability of the object's composition

If optical power equalization is performed among optical channels in Flex ROADM system, then power distribution uniformity is improved, but the system cannot simultaneously satisfy sub-carrier power equalization requirements

Engineering Contradiction:
Improveuniformity of optical power distributionVSAvoidcapability to satisfy sub-carrier equalization
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent implements a two-tier equalization architecture where channel-level equalization ensures uniform power distribution across optical channels, and sub-carrier-level equalization ensures proper power distribution among sub-carriers within each channel. Both levels operate simultaneously and independently, allowing the system to satisfy both channel uniformity and sub-carrier equalization requirements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent designs a universal optical power equalization system that can perform both channel-level and sub-carrier-level equalization functions through integrated control mechanisms. This multi-functional system uses a unified control framework that coordinates both equalization levels, enabling the system to simultaneously achieve channel power uniformity and sub-carrier power equality across all channels.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2985930B1Equalization method and device for optical power
Publication Date: 2018.03.07 ZTE CORP
  • EP2985930B1 patent drawingFigure 1~3
  • EP2985930B1 patent drawingFigure 4~5
  • EP2985930B1 patent drawingFigure 6~7

AI summary

Provided are an optical power equalization method and apparatus, which are applied to a flexible grid reconfigurable optical add drop multiplexer (Flex ROADM) system. The optical power equalization method includes: judging, according to an optical power monitoring result and an optical power control target value of an optical channel, whether optical power equalization needs to be performed on the optical channel; and when a judgement result is that the optical power equalization needs to be performed on the optical channel, performing equalization on an optical power of the optical channel and an optical power of each sub-carrier in the optical channel according to the optical power monitoring result. By means of the technical solution, the optical performance of the Flex ROADM system can satisfy the requirements.