Temperature-Controlled Nonlinear Resonator for Laser Wavelength Tuning

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Solution Overview

Problem

Existing methods for generating laser radiation using non-linear optical resonators face inefficiencies due to the need for precise temperature control and the use of piezo actuators, which are noisy and limit the ability to set multiple wavelengths to resonance simultaneously.

Innovation Solution

A temperature-controlled optical structure with an optically nonlinear solid-state medium in a resonator, where different temperatures are set within the active region to achieve phase matching and resonance for multiple wavelengths, eliminating the need for non-active zones and piezoelectric elements, allowing for efficient and compact operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If piezoelectric actuators are used to adjust resonator length for wavelength resonance, then resonance condition can be achieved, but high voltage noise and device complexity increase

Engineering Contradiction:
Improveresonance condition stabilityVSAvoidhigh voltage noise
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical piezoelectric actuator system with a thermal control system. Temperature actuators heat or cool specific sections of the nonlinear solid medium to adjust the resonator's optical path length through thermal expansion and refractive index changes, eliminating high voltage noise while achieving the same resonance adjustment function

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical parameter used for resonator length adjustment from mechanical displacement (piezoelectric) to temperature (thermal). By controlling the temperature of specific sections, the optical path length is adjusted through thermal effects, providing a cleaner, noise-free method for achieving wavelength resonance

Inventive Principle:
Principle #35Parameter changes

2Productivity

If single temperature control is used for phase matching, then phase matching efficiency improves, but multiple wavelengths cannot be simultaneously resonant

Engineering Contradiction:
Improveconversion efficiencyVSAvoidmulti-wavelength resonance capability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent divides the nonlinear solid medium into multiple temperature-controlled sections, each capable of independent temperature adjustment. This segmentation allows different sections to be optimized for different wavelengths simultaneously - one section maintains phase matching temperature while another adjusts resonator length for a specific wavelength, enabling multi-wavelength operation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different temperature conditions to different spatial sections of the nonlinear solid medium. Each section has locally optimized temperature characteristics - the first section is optimized for phase matching of the pump wave, while the second section is optimized for resonance of a specific output wavelength, allowing both functions to coexist

Inventive Principle:
Principle #3Local quality

3Reliability

If piezoelectric actuators are used for resonator adjustment, then resonance can be achieved, but device complexity and protective measures increase

Engineering Contradiction:
Improveresonance adjustment capabilityVSAvoidactuator system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex mechanical piezoelectric actuator system with simpler thermal control elements. Temperature actuators directly heat or cool the nonlinear solid medium sections, eliminating the need for high voltage power supplies, complex mounting structures, and protective shielding required by piezoelectric actuators

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 enables efficient generation of laser radiation by optimizing phase matching and resonator length adjustments via temperature control, increasing conversion efficiency and simplifying the resonator design, while avoiding the noise and high-voltage issues associated with piezo actuators.

Implementation Method 1

Phase matching is typically achieved by adjusting the (material-dependent) phase matching temperature of the solid medium. At the phase matching temperature, constructive interference occurs with the partial waves generated at different locations within the solid medium along the propagation path of the light

Methodology Applied
Scientific EffectPhase matching:

Implementation Method 2

Optical resonance of individual, or preferably all, wavelengths involved further increases the efficiency of the processes

Methodology Applied
Scientific EffectOptical resonance: Resonance

Implementation Method 3

This utilizes the coefficient of thermal expansion and/or the temperature dependence of the refractive index of the solid medium through which the light passes

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

This utilizes the coefficient of thermal expansion and/or the temperature dependence of the refractive index of the solid medium through which the light passes

Methodology Applied
Scientific EffectTemperature dependence of refractive index:

Implementation Method 5

The mirrors reflect the incoming wavefronts precisely back onto themselves, allowing the light to, in principle, circulate infinitely within the resonator

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3781986B1Method and apparatus for frequency conversion and amplification of laser radiation by means of nonlinear media in optical resonators
Publication Date: 2023.06.21 UNIV OF HAMBURG
  • EP3781986B1 patent drawingFigure 1
  • EP3781986B1 patent drawingFigure 2
  • EP3781986B1 patent drawingFigure 3

AI summary

An apparatus and a method for generating laser radiation by means of a temperature-controlled optical setup, comprising an optical nonlinear solid-state medium, arranged in a resonator, with an active region, wherein, with the assistance of constructive interference, pump radiation introduced into the solid-state medium generates emanated laser radiation, characterized by adapting the phases of the generated wavelengths, which are involved in the generation of the laser radiation, by setting a first temperature within a first portion of the active region and adapting the resonator length by setting a second temperature within a second portion of the active region.