CeO2 Anti-Reflection Film for Quantum Cascade Lasers
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Solution Overview
Problem
Existing quantum cascade laser elements face challenges in achieving high heat resistance and effective anti-reflection for laser light with a central wavelength of 7.5 μm or more, particularly with the anti-reflection films disclosed in prior art.
Innovation Solution
A quantum cascade laser element incorporating an anti-reflection film composed of at least one layer of CeO2 film formed by continuous sputtering and vacuum evaporation, or multiple layers formed by discrete sputtering and vacuum evaporation, which effectively reduces reflectance and enhances heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-reflection film is used for laser light with a central wavelength of 7.5 μm or more, then the reflectance is reduced effectively, but the heat resistance of films other than the CeO2 film is insufficient
Solution Approach 1:
The patent employs a composite anti-reflection film structure consisting of multiple layers with different materials and properties. The film includes a CeO2 layer (providing heat resistance), a YF3 or CeF3 layer (providing low refractive index for anti-reflection), and optionally a SiO2 or Al2O3 layer (providing additional protection and functional properties). This composite structure allows each layer to contribute its specific advantages, achieving both effective anti-reflection for 7.5 μm wavelength laser light and sufficient heat resistance.
Solution Approach 2:
The patent applies different material properties to different layers of the anti-reflection film to optimize specific functions at different levels. The CeO2 layer is positioned to provide thermal stability and heat resistance, while the YF3/CeF3 layers are positioned to provide the necessary refractive index matching for anti-reflection. This local optimization of material properties throughout the film structure resolves the contradiction between anti-reflection effectiveness and heat resistance.
2Reliability
If a multi-layer anti-reflection film structure is implemented, then the anti-reflection performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent divides the anti-reflection film into multiple functional layers, each with a specific thickness and material composition optimized for its role. The segmentation allows independent optimization of each layer's properties (refractive index, thickness, material) to achieve overall anti-reflection performance while maintaining manageable manufacturing complexity through systematic layer design.
Solution Approach 2:
The patent optimizes specific parameters of each film layer (thickness, refractive index, material composition) to achieve the desired anti-reflection performance. By carefully controlling these parameters during manufacturing, the complex multi-layer structure can be produced with consistent quality and performance, reducing the practical impact of the increased structural complexity.
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 proposed solution ensures reliable reduction of reflectance for laser light with a central wavelength of 7.5 μm or more, improves adhesion, prevents short circuits, and maintains high heat resistance, effectively functioning for quantum cascade laser elements and devices.
Implementation Method 1
an anti-reflection film that effectively functions for laser light having a central wavelength of 7.5 μm or more
Implementation Method 2
an anti-reflection film including an insulating film that is a CeO2 film, a first refractive index film that is a YF3 film or a CeF3 film
Implementation Method 3
at least one layer of a CeO2 film formed by continuous sputtering and vacuum evaporation
Implementation Method 4
at least one layer of a CeO2 film formed by continuous sputtering and vacuum evaporation
Data Source
AI summary
A quantum cascade laser element includes: a semiconductor substrate; a semiconductor laminate including an active layer and having a first end surface and a second end surface facing each other in an optical waveguide direction; a first electrode; a second electrode; and an anti-reflection film formed on the first end surface. The semiconductor laminate is configured to oscillate laser light having a central wavelength of 7.5 μm or more. The anti-reflection film includes at least one of at least one layer of a CeO2 film formed by continuous sputtering and vacuum evaporation and a plurality of layers of CeO2 films formed by discrete sputtering and vacuum evaporation.