Dual-Polarization Tunable Laser with Independent Frequency Control

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Solution Overview

Problem

Existing dual-frequency lasers lack the ability to independently adjust the two optical frequencies and are sensitive to temperature fluctuations, which affects their stability and accuracy in applications like atomic clocks.

Innovation Solution

A dual-polarization, dual-frequency laser design incorporating two electro-optical crystals with paired electrodes, allowing independent control of the optical frequencies through judicious voltage application and specific orientation of the optical axes, and a piezoelectric transducer for cavity length adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single electro-optical crystal is used to control frequency, then the device complexity is reduced, but the ability to independently adjust the two optical frequencies is lost

Engineering Contradiction:
Improvenumber of electro-optical crystalsVSAvoidindependent frequency adjustment capability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The single electro-optical crystal is segmented into two separate crystals, each with its own pair of electrodes. This segmentation allows independent control of the ordinary and extraordinary polarization modes, enabling independent adjustment of the two optical frequencies while maintaining a relatively simple overall device structure.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If the cavity length is fixed, then the device complexity is reduced, but the sensitivity to temperature fluctuations increases

Engineering Contradiction:
Improvecavity length adjustment mechanismVSAvoidtemperature stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The fixed cavity length is transformed into a dynamically adjustable parameter through the introduction of a piezoelectric transducer. This allows real-time compensation for temperature-induced cavity length changes, maintaining frequency stability without significantly increasing device complexity.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If no piezoelectric transducer is used, then the device complexity is reduced, but the frequency stability deteriorates

Engineering Contradiction:
Improvepresence of piezoelectric transducerVSAvoidfrequency stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The piezoelectric transducer is integrated into a feedback control system that monitors the optical frequencies and adjusts the cavity length in real-time to compensate for temperature fluctuations. This feedback mechanism ensures high frequency stability while keeping the overall device complexity manageable.

Inventive Principle:
Principle #23Feedback

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

Enables independent adjustment of optical frequencies, reducing sensitivity to temperature fluctuations and enhancing stability and accuracy for applications requiring precise frequency control.

Implementation Method 1

a first electro-optical crystal in a first material having a first optical axis with the same direction as the first linear polarization and comprising a first pair of electrodes adapted to apply a first voltage within the first electro-optical crystal

Methodology Applied
Scientific EffectElectro-optic effect: Electro-Optic Effects

Implementation Method 2

at least one birefringent element adapted to exhibit birefringence such that the intracavity laser beam exhibits the first frequency according to the first linear polarization and presents the second frequency according to the second linear polarization

Methodology Applied
Scientific EffectBirefringence: Birefringence

Implementation Method 3

a piezoelectric transducer for cavity length adjustment

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP4542795B1Dual-frequency bi-polarization tunable laser source.
Publication Date: 2026.03.11 THALES SA
  • EP4542795B1 patent drawingFigure 1~2A
  • EP4542795B1 patent drawingFigure 2B
  • EP4542795B1 patent drawingFigure 3

AI summary

A tunable, bi-polarized, bi-frequency laser source (1) adapted to emit an output beam (FS) having a first frequency vV according to a first linear polarization and a second frequency vH according to a second linear polarization perpendicular to the first linear polarization, the laser source comprising an optical cavity (C) including the following elements arranged between a highly reflective element (M1) and an output coupler (M2): - a second electro-optical crystal (EO2) in a second material having a second optical axis (x2) with the same direction and orientation as the second linear polarization and including a second pair of electrodes (E2) adapted to apply within the second electro-optical crystal a second voltage V2 along a direction of the second linear polarization, the first and second materials being adapted so that there exists a first and a second voltage V1,V2 adapted to independently control a value of the first frequency vV and a value of the second frequency vH included in the output beam (FS).