Transparent Heat Sink Direct Bonding for Solid-State Lasers
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Solution Overview
Problem
Solid-state laser systems face limitations in thermal conductivity, mechanical stability, and optical properties due to the use of adhesive layers, which can lead to opacity and optical absorption, restricting light extraction and input of optical pump beams.
Innovation Solution
A direct bonding process between the optical gain material and a transparent heat sink with high thermal conductivity, eliminating intermediate adhesive layers and enabling enhanced thermal and mechanical performance, along with a transparent interface for improved light transmission and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive layers are used to join the lasing medium to the cooling member, then the joining process is simple and straightforward, but the thermal conductivity of the system is limited and mechanical stability problems occur
Solution Approach 1:
The patent removes the adhesive layer from the system entirely, extracting the problematic intermediate material that limited thermal conductivity. The lasing medium is directly bonded to the cooling member through mechanical interlocking and surface treatment, eliminating the thermal barrier that adhesives created while maintaining ease of assembly through direct bonding techniques.
Solution Approach 2:
The patent employs asymmetric surface treatment where the cooling member receives specific surface preparation (roughening, coating, or anodization) that is not applied to the lasing medium. This asymmetric approach creates optimal bonding conditions on the cooling member side while preserving the optical and thermal properties of the lasing medium surface.
2Ease of manufacture
If adhesive layers are used to join the lasing medium to the cooling member, then the joining process is simple, but mechanical stability is compromised
Solution Approach 1:
The patent applies surface treatment to the cooling member before the bonding process. This preliminary action of roughening, coating, or anodizing the cooling member surface creates mechanical interlocking features and chemical bonding sites that significantly enhance the strength of the direct bond between the cooling member and lasing medium.
Solution Approach 2:
The patent applies different surface properties to different parts of the system. The cooling member receives surface treatment (roughening, coating, or anodization) to enhance bonding, while the lasing medium maintains its original surface quality for optimal optical performance. This local differentiation ensures both mechanical stability and optical functionality.
3Ease of manufacture
If adhesive layers are used to join the lasing medium to the cooling member, then the joining process is straightforward, but optical properties are limited due to opacity and absorption
Solution Approach 1:
The patent removes the adhesive layer that caused optical absorption and opacity. By directly bonding the lasing medium to the cooling member, the optical path is cleared of materials that absorbed pump light and scattered output radiation, thereby improving optical transparency and intensity without complicating the manufacturing process.
Solution Approach 2:
The patent applies surface treatment only to the cooling member, leaving the lasing medium surface untouched and optically perfect. This localized approach ensures that the bonding enhancement occurs only where needed for mechanical attachment, while the optical surfaces remain pristine for maximum light transmission and minimal absorption.
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 solution significantly improves thermal performance, mechanical stability, and optical transparency, allowing for efficient light extraction and pumping from multiple sides, and simplifies the laser system design while reducing production costs.
Implementation Method 1
the thermal performance of the system is significantly improved. Therefore, the thermal performance is ultimately limited only by the thermal conductivities of the optical gain material or heat sink, whichever is lowest
Implementation Method 2
the heat sink having a high thermal conductivity, in particular greater than or equal to 149 W/m*K
Implementation Method 3
the heat sink is transparent, in particular over a wavelength range of 200 nm to 4000 nm, preferably with an absorption coefficient of −1
Implementation Method 4
Within the context of this invention, the term optical gain material should be understood as a material capable of generating optical gain, wherein is understood that optical gain describes the optical amplification process in the material
Data Source
AI summary
A solid-state laser active medium comprising an optical gain material; a heat sink, wherein the heat sink is transparent, in particular over a wavelength range of 200 nm to 4000 nm, preferably with an absorption coefficient of <1 cm−1; the heat sink having a high thermal conductivity, in particular ≥149 W/(m*K); wherein the optical gain material and the heat sink exhibit a root-mean square, RMS, surface roughness of <1 nm; wherein the optical gain material is attached to the transparent heat sink by direct bonding.