Multi-Metal Reflective Diffraction Grating for Ultrashort Pulse Resistance
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Solution Overview
Problem
Current diffraction gratings used in high power lasers, particularly for ultrashort pulse laser applications, face limitations in flux resistance and spectral bandwidth, leading to potential damage during pulse compression.
Innovation Solution
A reflective diffraction grating structure is proposed, featuring grating lines on a substrate with an external reflective layer and an intermediate metal layer. The external reflective layer is made of a high reflection coefficient metal, while the intermediate metal layer, with a higher electron-phonon coupling coefficient, aids in heat dissipation and increases flux resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer gold reflective layer is used in the diffraction grating, then the diffraction efficiency is high and the material is corrosion-resistant, but the flux resistance to ultrashort-pulse laser is limited
Solution Approach 1:
The single gold reflective layer is segmented into multiple layers: an external reflective layer (gold or silver) and an intermediate metal layer (aluminum, copper, or nickel). This segmentation allows each layer to perform specialized functions - the external layer provides high reflectivity while the intermediate layer enhances flux resistance by managing thermal energy distribution.
Solution Approach 2:
The patent creates a composite structure combining different metals with complementary properties. The external reflective layer (high reflection coefficient) is combined with an intermediate layer (high electron-phonon coupling coefficient), forming a composite material system that achieves both high diffraction efficiency and enhanced flux resistance to ultrashort-pulse lasers.
2Use of energy by moving object
If the external reflective layer thickness is increased to improve reflection coefficient, then the diffraction efficiency increases, but the thermal management capability deteriorates
Solution Approach 1:
The patent optimizes the thickness parameters of both layers within specific ranges. The external reflective layer thickness is controlled at 10-100 nm to maintain high reflection coefficient, while the intermediate layer thickness is set at 50-200 nm to provide sufficient thermal management capability through electron-phonon coupling, achieving a balance between optical performance and thermal management.
3Reliability
If a multi-layer dielectric grating is used to improve flux resistance, then the flux resistance increases, but the spectral bandwidth is limited
Solution Approach 1:
The patent uses homogeneous metal materials (gold, silver, aluminum, copper, nickel) with inherent broad spectral response characteristics. Unlike multi-layer dielectric gratings that rely on interference effects with narrow bandwidth, the metal-based approach provides homogeneous optical properties across a broad spectral range while maintaining enhanced flux resistance through the multi-layer metal structure.
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 multi-metal diffraction grating design enhances the flux resistance and maintains high diffraction efficiency over a wide spectral bandwidth, effectively resisting high peak power ultrashort pulse laser flux and extending its operational domain in duration and fluence.
Implementation Method 1
The external reflective layer is consisted of a first metal and the intermediate metal layer is consisted of another metal, the other metal having a higher electron-phonon coupling coefficient than the electron-phonon coupling coefficient of the first metal
Implementation Method 2
a reflective diffraction grating structure is proposed, featuring grating lines on a substrate with an external reflective layer
Implementation Method 3
This multi-metal diffraction grating design enhances the flux resistance and maintains high diffraction efficiency over a wide spectral bandwidth
Data Source
AI summary
Disclosed is a reflective diffraction grating including at least one intermediate metal layer arranged between the external reflective layer and a surface of the substrate including the grating lines, the external reflective layer being consisted of a first metal and the intermediate metal layer being consisted of another metal, the other metal having a higher electron-phonon coupling coefficient than the electron-phonon coupling coefficient of the first metal or metal alloy, the external reflective layer having a thickness in a range having a lower limit determined by a reflection coefficient of the first metal and an upper limit determined by a thermal diffusion length of the first metal, and the intermediate metal layer having another thickness greater than a minimum value in such a way as to increase the high peak power ultrashort pulse light flux resistance of the reflective diffraction grating.