Apparatus and method for providing a control signal for stabilizing a frequency of an optical output of a laser system

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Solution Overview

Problem

Existing laser systems with optical resonators face limitations in stability due to mechanical and thermal noise, which affect the precision of frequency stabilization, particularly in ultrastable laser systems used for quantum computing and high-precision clocks.

Innovation Solution

An apparatus with an optical resonator containing a doped material and a thermal insulation system, which includes a matrix doped with a rare-earth element, operates at cryogenic temperatures to reduce thermal noise and mechanical vibrations, utilizing spectral hole burning for enhanced sensitivity and stability, allowing for a compact and cost-effective design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an optical resonator is used for frequency stabilization, then frequency stability is improved, but mechanical noise and thermal noise increase

Engineering Contradiction:
Improvefrequency stabilityVSAvoidmechanical noise and thermal noise
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the temperature parameter by cooling the optical resonator to cryogenic temperatures (below 77K, preferably below 4K). This parameter change reduces thermal noise and mechanical vibrations in the resonator, thereby improving frequency stability while mitigating the harmful thermal and mechanical effects.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent places the optical resonator in a vacuum environment (inert atmosphere without gas molecules). This eliminates thermal conduction and convection, reducing thermal noise and mechanical vibrations from the environment, thus improving frequency stability while minimizing harmful thermal and mechanical interference.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

2Object-affected harmful factors

If the optical resonator is cooled to cryogenic temperatures, then thermal noise is reduced, but device complexity increases

Engineering Contradiction:
Improvethermal noiseVSAvoidcooling system complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent utilizes the phase transition of cryogenic fluids (such as liquid nitrogen at 77K or liquid helium at 4K) to achieve cooling. By immersing the optical resonator in these cryogenic fluids, the system achieves cryogenic temperatures without requiring complex active cooling mechanisms, thus reducing thermal noise while keeping the cooling system relatively simple.

Inventive Principle:
Principle #36Phase transitions

3Volume of moving object

If the optical resonator length is reduced for compact design, then device size is decreased, but frequency stability deteriorates

Engineering Contradiction:
Improveresonator sizeVSAvoidfrequency stability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent changes the temperature parameter to cryogenic levels, which fundamentally alters the thermal expansion characteristics and mechanical properties of the resonator materials. This parameter change allows the resonator to maintain high frequency stability even at reduced lengths, as the cryogenic environment minimizes thermal fluctuations and mechanical vibrations that would otherwise degrade stability in compact resonators.

Inventive Principle:
Principle #35Parameter changes

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

The apparatus provides a highly stable control signal with reduced noise, enabling ultrastable laser systems suitable for quantum computing and high-precision applications, while being compact and cost-efficient for integration into photonic integrated circuits and satellite systems.

Implementation Method 1

The doped material comprises a matrix doped with a rare-earth element and is adapted for spectral-hole burning therein

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

The thermal insulation system is adapted to thermally insulate the optical resonator from an environment outside of the thermal insulation system

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

An optical resonator, sometimes also referred to as an optical cavity or as a Fabry-Perot resonator

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP4618327A1Apparatus and method for providing a control signal for stabilizing a frequency of an optical output of a laser system
Publication Date: 2025.09.17 TECHNISCHE UNIVERSITAT MUNCHEN
  • EP4618327A1 patent drawingFigure 1~4c
  • EP4618327A1 patent drawingFigure 5~7
  • EP4618327A1 patent drawingFigure 8~10

AI summary

An apparatus is adapted to provide a control signal for stabilizing a frequency of an optical output of a laser system. The apparatus comprises an optical resonator, a doped material arranged in the optical resonator, and a thermal insulation system. The doped material comprises a matrix doped with a rare-earth element. The thermal insulation system is adapted to thermally insulate the optical resonator from an environment outside of the thermal insulation system. The apparatus is adapted to provide the control signal based on an optical signal from the resonator when an optical input is provided to the resonator. The control signal is associated with a length of the optical resonator and/or with a refractive index of the doped material.