Coherent Optical Receiver Nonlinear Distortion Coefficient Determination

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Solution Overview

Problem

Current methods for mitigating optical nonlinear effects in fiber optic communications are computationally intensive and require human intervention to determine fiber link parameters, leading to inaccurate results and the need for frequent recalculations with changes in link parameters.

Innovation Solution

A coherent optical receiver determines non-linear perturbation distortion coefficients automatically from received optical data without knowledge of fiber link parameters, using analysis of electrical signals representative of points on an IQ plane to calculate perturbative coefficients and adjust for distortion, enabling automatic and operator-independent mitigation of optical nonlinear effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If back propagation is used to mitigate nonlinear effects, then mitigation effectiveness is improved, but computational complexity increases significantly

Engineering Contradiction:

Improvenonlinear mitigation effectivenessVSAvoidcomputational complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the complex back propagation process into a simplified perturbative model that uses pre-calculated distortion coefficients. Instead of performing full back propagation computations, the system divides the nonlinear distortion into manageable perturbation terms that can be compensated more efficiently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the computational parameters by using perturbative distortion coefficients (Cm,n) that characterize nonlinear effects without requiring full back propagation. These coefficients are determined once and then used for efficient real-time compensation, transforming the computational approach from intensive iterative processing to coefficient-based calculation.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If manual determination of fiber link parameters is performed, then perturbation coefficients can be calculated, but time consumption and cost increase

Engineering Contradiction:

Improveparameter determination accuracyVSAvoidtime for parameter determination

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs self-service by automatically determining the perturbative distortion coefficients using the received optical signal itself. The receiver uses the actual signal characteristics to calculate the coefficients without requiring external manual measurement or knowledge of fiber link parameters, making the system autonomous and adaptive.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent implements feedback by using the received optical signal to determine the distortion coefficients, which are then applied to compensate for nonlinear effects. This closed-loop approach allows the system to automatically adapt to changing fiber conditions without manual intervention.

Inventive Principle:

Principle #23Feedback

3Productivity

If manual measurement of fiber link parameters is performed, then distortion coefficients can be determined, but measurement accuracy may be insufficient

Engineering Contradiction:

Improvecoefficient determination efficiencyVSAvoidparameter measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces manual mechanical measurement processes with automated optical signal-based determination. Instead of using physical measurement tools and human operators to characterize fiber parameters, the system uses the optical signal itself to derive the distortion coefficients through mathematical processing, achieving both higher accuracy and efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If fiber link parameters are manually determined, then initial distortion coefficients can be calculated, but any parameter changes require additional manual determinations

Engineering Contradiction:

Improveadaptability to parameter changesVSAvoidoperational simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent makes the system dynamic by enabling real-time determination of distortion coefficients from the received signal. When fiber link parameters change, the system automatically detects and recalculates the coefficients without requiring manual re-measurement, maintaining adaptability while preserving operational simplicity.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9906309B2System and method for determining nonlinear mitigation perturbative distortion coefficients using a received optical signal

Publication Date: 2018.02.27 INFINERA CORP

AI summary

A processor circuit is provided in a coherent optical receiver module. The processor receives a series of electrical signals over a time period, representative of a series of optical signals received at instants of time within the time period. Each of the electrical signals is indicative of a respective one of a plurality of points on an IQ plane, each of the points being spaced from one of a plurality of predetermined points in the IQ plane by a corresponding one of a plurality of distortion values. In addition, the processor circuit calculates one or more perturbative coefficients based on one or more of the distortion values and determines data from the series of electrical signals based on the perturbative coefficient.