Wavemeter Feedback Control for Tunable Laser Wavelength Stability

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Solution Overview

Problem

Tunable lasers face challenges in maintaining stabilization due to wavelength drift caused by environmental changes, requiring effective calibration and reconfiguration methods to ensure system performance in applications like optical communications and spectroscopy.

Innovation Solution

A system comprising a tunable laser, a wavemeter, and analog functions, utilizing a fast feedback loop for immediate wavelength adjustments and a slow feedback loop for controlled tuning, with a controller managing laser drive signals, gain coefficients, and phase set points to stabilize the laser output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a tunable laser is used to enable wavelength reconfiguration, then adaptability is improved, but wavelength stability deteriorates due to environmental drift

Engineering Contradiction:
Improvewavelength reconfiguration capabilityVSAvoidwavelength stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback control system using a wavemeter to continuously monitor the laser wavelength and provide correction signals. The wavemeter measures the actual wavelength and feeds this information back to control circuitry that adjusts tuning elements (such as DBR gratings or phase shifters) to compensate for drift and maintain the desired wavelength setpoint, thereby resolving the contradiction between tunability and stability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically changes control parameters (currents applied to tuning elements, phase shifts) based on feedback from the wavemeter. By continuously adjusting these parameters in response to measured wavelength deviations, the system maintains stable operation while preserving the ability to reconfigure to different wavelength sets as needed.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If a fast feedback loop is implemented for immediate wavelength corrections, then wavelength stability is improved, but device complexity increases

Engineering Contradiction:
Improvewavelength stabilityVSAvoidcontrol system complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent segments the control system into distinct functional blocks: a wavemeter for wavelength measurement, a control circuit for processing error signals, and separate tuning element control paths. This modular segmentation allows the fast feedback loop to be implemented systematically with clearly defined interfaces between components, managing complexity through structured decomposition of the overall control function.

Inventive Principle:
Principle #1Segmentation

3Manufacturing precision

If multiple tunable elements are used for precise wavelength control, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:
Improvewavelength control precisionVSAvoidlaser structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple tuning functions into an integrated control architecture where several tunable elements (such as multiple DBR sections or phase shifters at different locations in the laser cavity) are controlled by a unified feedback system. The wavemeter provides a single wavelength measurement that drives coordinated adjustment of all tuning elements, merging their individual effects to achieve precise wavelength control while managing complexity through centralized control logic.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3940900B1Tunable laser stabilization
Publication Date: 2024.02.14 NOKIA SOLUTIONS & NETWORKS OY
  • EP3940900B1 patent drawingFigure 1
  • EP3940900B1 patent drawingFigure 2
  • EP3940900B1 patent drawingFigure 3

AI summary

Various example embodiments for supporting tuning of a tunable laser are presented. Various example embodiments for supporting tuning of a tunable laser may be configured to support tuning of a tunable laser based on a wavemeter. Various example embodiments for supporting tuning of a tunable laser based on a wavemeter may be configured to support tuning of the tunable laser based on a fast feedback loop from the wavemeter to the tunable laser and a slow feedback loop from the wavemeter to the tunable laser that is controlled by a controller.