Optical Channel Power Optimization for Noise Minimization

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Solution Overview

Problem

Existing optical communication systems face challenges in optimizing optical signal quality due to the accumulation of linear and nonlinear noise during propagation, which limits the system's performance and requires significant computational effort to determine optimal launch channel powers.

Innovation Solution

A method to determine optimal optical channel powers for each section of an optical communications link by minimizing the sum of linear and nonlinear noise, allowing for individual optimization of channel powers rather than a common launch power across all sections, using a controller to generate control signals for setting target channel powers based on noise coefficients and noise figures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a common launch channel power is used for all sections, then the system is simple to operate, but the optical signal quality cannot be optimized for each section with different noise characteristics

Engineering Contradiction:

Improvesimplicity of power settingVSAvoidoptical signal quality

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent divides the optical communication link into multiple sections, each with its own optimal channel power setting. Instead of using a single common launch power for the entire link, the system determines separate optimal powers for each section based on their specific noise characteristics (linear noise from amplifiers and nonlinear noise from fibre), thereby optimizing signal quality while maintaining operational simplicity through automated control

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each section of the optical link is assigned its own specific optimal channel power setting tailored to its local noise conditions. The system accounts for section-specific parameters such as amplifier noise figures and fibre span lengths, allowing each section to operate at the power level that minimizes its particular combination of linear and nonlinear noise

Inventive Principle:

Principle #3Local quality

2Reliability

If simulations are run to determine optimal launch channel powers, then the optical signal quality can be optimized, but the computational effort required is large

Engineering Contradiction:

Improveoptical signal qualityVSAvoidcomputational time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent uses analytical expressions that model the noise characteristics of optical links as functions of channel power. By changing the parameters in these expressions (such as amplifier noise figures, fibre losses, and span lengths), the system can determine optimal powers through mathematical calculations rather than time-consuming simulations, significantly reducing computational time while maintaining accuracy

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces complex numerical simulations with analytical mathematical models. Instead of running time-consuming Monte Carlo or finite element simulations to determine optimal launch powers, the system uses closed-form expressions that combine linear noise (from amplifiers) and nonlinear noise (from fibre) components, enabling rapid calculation of optimal powers

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the optical channel power is increased to improve signal-to-noise ratio, then the linear noise decreases, but the nonlinear noise increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidnonlinear noise

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent treats both linear noise (from amplifiers) and nonlinear noise (from fibre) as quantifiable parameters that can be modeled and optimized. By expressing both noise types analytically as functions of channel power, the system can identify the optimal power level where the combined noise is minimized, effectively converting the harmful effect of power-dependent noise into a solvable optimization problem

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 approach enhances the Q factor, increases the optical reach, reduces the need for signal regenerators, and increases system margins, enabling larger tolerances in component specifications and spectral management.

Implementation Method 1

Amplified spontaneous emission, ASE, noise accumulation is unavoidably related to the optical amplification, performed via erbium-doped fibre amplifiers, EDFA, or Raman amplifiers

Methodology Applied

Scientific EffectAmplified spontaneous emission:

Data Source

PatentUS9641252B2Method of optimizing optical signal quality in an optical communications link, optical network element and optical communications link

Publication Date: 2017.05.02 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method of optimizing optical signal quality in an optical communications link comprising a plurality of sections each comprising an optical amplification apparatus and an optical fiber span, the method comprising: for each section, determining a respective optimal optical channel power which minimizes a sum of an indication of a respective linear optical noise and an indication of a respective nonlinear optical noise; and generating and transmitting at least one control signal arranged to cause a target optical channel power of each section to be set to the respective optimal optical channel power.