Multi-Laser Wavelength Control Using Reference Signals

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Solution Overview

Problem

In optical networks, particularly in WDM systems, relative wavelength drift between laser sources leads to increased guard bands, reducing spectral efficiency due to adjacent channel crosstalk caused by optical carrier wavelength drift.

Innovation Solution

A method and apparatus for multi-laser wavelength control involving a multi-line source with fixed spacing wavelength lines, where the output is split into wavelength reference signals, combined with optical channels, and the center wavelength of each channel is tuned based on determined wavelength offsets to reduce beating frequencies, using optical splitters, combiners, analyzers, and laser controllers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If guard bands are increased between adjacent channels, then adjacent channel crosstalk is reduced, but spectral efficiency deteriorates

Engineering Contradiction:

Improveadjacent channel crosstalkVSAvoidspectral efficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The system implements feedback control by continuously monitoring the wavelength of each laser source and adjusting it to maintain alignment with the center of its assigned optical channel. The wavelength controller receives information about wavelength deviations and applies corrective adjustments, creating a closed-loop control system that actively compensates for drift without requiring increased guard bands.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically changes the wavelength parameter of each laser source to optimize performance. By actively tuning and adjusting the wavelength of individual laser sources based on real-time measurements and control signals, the system maintains precise wavelength alignment, thereby reducing the need for conservative guard band spacing and improving spectral efficiency.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If laser wavelength drift is reduced through active control, then spectral efficiency is improved, but device complexity increases

Engineering Contradiction:

Improvespectral efficiencyVSAvoidcontrol system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The control system is segmented into independent wavelength control modules, each responsible for a specific laser source. This modular approach allows each controller to operate autonomously, managing only its assigned laser without requiring complex coordination with other lasers. The segmentation simplifies the overall control architecture while achieving precise wavelength management across multiple sources.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system introduces a wavelength controller as an intermediary component between the laser sources and the optical channels. This intermediary device mediates the wavelength alignment by continuously monitoring and adjusting laser output, simplifying the control task compared to direct complex multi-laser coordination. The intermediary absorbs the complexity of wavelength management, allowing the rest of the system to operate with simpler assumptions.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If multiple wavelength reference signals are used, then wavelength alignment precision is improved, but measurement and detection difficulty increases

Engineering Contradiction:

Improvewavelength alignment precisionVSAvoidwavelength offset detection difficulty

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The system creates simplified copies or representations of the wavelength reference signals that are easier to measure and compare. Instead of directly measuring complex multi-wavelength signals, the system uses reference copies that maintain the essential alignment information in a more measurable form, reducing the difficulty of detection while preserving alignment precision.

Inventive Principle:

Principle #26Copying

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 effectively reduces relative wavelength drift between laser sources, minimizing guard bands and enhancing spectral efficiency in WDM systems by precisely aligning channel wavelengths with reference lines, thereby improving monitoring and control of multiple laser sources.

Implementation Method 1

involving a multi-line source with fixed spacing wavelength lines, where the output is split into wavelength reference signals

Methodology Applied

Scientific EffectOptical splitting:

Implementation Method 2

combined with optical channels

Methodology Applied

Scientific EffectOptical combining:

Implementation Method 3

the center wavelength of each channel is tuned based on determined wavelength offsets

Methodology Applied

Scientific EffectWavelength offset detection:

Data Source

PatentUS10979167B2Systems and method of multi-laser wavelength control

Publication Date: 2021.04.13 HUAWEI TECH CO LTD

AI summary

Methods and apparatus are provided for wavelength control of multiple independent laser sources to reduce relative wavelength drift between the different laser sources. According to some aspects, multiple laser wavelength control is provided using a multi-line source as a wavelength reference. According to other aspects, multiple laser wavelength control is provided using a single wavelength sensing device. The multiple independent laser sources could generate the constituent optical channels of a super-channel. Benefits could include reduced guard band width and increased spectral efficiency within the super-channel.