Diffusion-Bonded Optical Cooling Interface for Low-Fresnel Lasers

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Solution Overview

Problem

The bonding of optical materials with cooling materials in laser oscillators leads to significant Fresnel reflection losses due to differences in refractive indices, degrading the quality of laser light transmission.

Innovation Solution

A joined body is formed by diffusively joining materials with a diffusive entry length of atoms between 1.0 nm to 100 nm, allowing for efficient heat dissipation and minimizing interference fringes, using a manufacturing method that includes pressurizing and heating the materials with pulse electric current to achieve a strong bond without adhesives.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If optical materials are bonded to cooling materials in laser oscillators, then heat dissipation efficiency is improved, but Fresnel reflection losses increase due to refractive index differences

Engineering Contradiction:
Improveheat dissipation efficiencyVSAvoidFresnel reflection losses
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

An intermediate layer with refractive index gradient is introduced between the optical material and cooling material. This intermediate layer acts as a mediator that gradually transitions the refractive index from the optical material to the cooling material, reducing Fresnel reflection losses while maintaining effective heat dissipation through the cooling material.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The refractive index parameter is changed gradually across the intermediate layer rather than having an abrupt transition. By creating a gradient in refractive index, the optical impedance mismatch is reduced, minimizing reflection losses while the thermal conductivity parameter remains optimized for heat dissipation.

Inventive Principle:
Principle #35Parameter changes

2Strength

If materials are joined by diffusion bonding, then bonding strength is improved, but interference fringes are generated affecting optical quality

Engineering Contradiction:
Improvebonding strengthVSAvoidoptical quality
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The diffusion bonding parameters (temperature, time, pressure) are precisely controlled to achieve a diffusive entry length within 1.0 nm to 100 nm. This parameter control ensures strong bonding while limiting the diffusion zone to prevent interference fringe generation that would degrade optical quality.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The diffusion bonding is applied locally at the interface between materials with different local requirements. The diffusive entry length is controlled to be sufficient for bonding strength but limited to prevent optical interference, creating different quality zones: strong bonding at the interface and high optical quality in the bulk materials.

Inventive Principle:
Principle #3Local quality

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 enhances optical quality by reducing Fresnel losses and thermal aberrations, enabling efficient heat dissipation and maintaining transparency, thus improving the performance of laser oscillators and amplifiers.

Implementation Method 1

parts of atoms contained in each one of the materials diffusively enter correspondingly the other one of the materials in such a degree that an interference fringe is not generated in the joined body

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

a manufacturing method that includes pressurizing and heating the materials with pulse electric current

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 3

the joined body is capable of transmitting light

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 4

an amount of loss caused by a Fresnel reflection is large when light is transmitted through the bonded body

Methodology Applied
Scientific EffectFresnel reflection: Reflection

Implementation Method 5

a resonator being placed in such a way as to sandwich the joined body and resonating light pumped by the joined body

Methodology Applied
Scientific EffectLaser oscillation: Laser

Implementation Method 6

a pumping light source emitting light to the joined body in such a way as to pump the joined body

Methodology Applied
Scientific EffectLight amplification: Laser

Data Source

PatentEP3787133B1Bonded body, laser oscillator, laser amplifier, and method for producing bonded body
Publication Date: 2024.10.23 INTER UNIV RES INST NAT INST OF NATURAL SCI
  • EP3787133B1 patent drawingFigure 1
  • EP3787133B1 patent drawingFigure 2
  • EP3787133B1 patent drawingFigure 3

AI summary

A joined body (10) includes an optical material (11) and a cooling material (12) that are capable of transmitting light and are joined together. At a joining interface between the optical material (11) and the cooling material (12), the joined body (10) is capable of transmitting light, and also an atom contained in the optical material (11) diffusively enters the cooling material (12) in such a degree that an interference fringe is not generated in the joined body (10). A diffusive entry length of an atom contained in the optical material (11) into the cooling material (12) may be in a range from approximately 1.0 nm to approximately 10 µm.