Solid-State Light Converter Filler Layer for Optical Coatings
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Solution Overview
Problem
Ceramic light conversion materials face challenges in handling high-power incident light, optimizing optical coatings for both excitation and emission light, and thermal dissipation, which affects their performance in applications like high-power laser projectors.
Innovation Solution
A filler layer with a low optical refractive index is introduced between the ceramic light conversion material and optical coatings, including anti-reflective and high-reflective coatings, to enhance light transmission and collection, and a metallic coating is used for thermal management, allowing for improved optical performance and thermal dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an optical coating is applied directly to the solid-state light conversion material, then the optical performance should be improved, but the porosity of the solid-state material disables the function of the coating
Solution Approach 1:
A filler layer is introduced as an intermediary between the porous solid-state light conversion material and the optical coating. This filler layer has low porosity and provides a suitable surface for the optical coating to adhere to and function properly, while the solid-state material provides the light conversion function. The filler layer thus mediates between the two components to resolve the contradiction.
2Power
If the solid-state light conversion material is used to handle high power incident light, then the power handling capability is improved, but thermal dissipation becomes a significant concern
Solution Approach 1:
The filler layer acts as a thermal interface between the solid-state light conversion material and the substrate. It provides a pathway for heat dissipation from the high-power light conversion material to the substrate, while maintaining the optical and structural integrity of the overall structure. This resolves the thermal management issue associated with high power operation.
3Illumination intensity
If anti-reflective and high-reflective coatings are applied to the solid-state light conversion material, then the optical performance is improved, but the coating application becomes difficult due to surface porosity
Solution Approach 1:
The filler layer provides a non-porous, smooth surface that is suitable for applying anti-reflective and high-reflective coatings. This intermediary layer eliminates the surface porosity issues of the solid-state material, allowing standard coating techniques to be used effectively while maintaining the underlying light conversion functionality.
4Reliability
If the filler layer thickness is increased to achieve optical smoothness, then the optical coating function is improved, but the extraction of converted light may be reduced
Solution Approach 1:
The thickness of the filler layer is optimized to a specific range that balances two competing requirements: it must be thick enough to provide optical smoothness and support the coating, but thin enough to minimize light extraction losses. This parameter optimization resolves the contradiction between coating functionality and light extraction efficiency.
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 enables increased light conversion efficiency by up to 10% and improved thermal management, reducing thermal quenching and enhancing the handling of high-power light conditions.
Implementation Method 1
Light conversion (or wavelength conversion) materials such as phosphors are used in a variety of applications
Implementation Method 2
The filler layer, especially its thickness, may be configured to be optically smooth in microscopic dimensions
Implementation Method 3
A single or multilayer anti-reflective (AR) coating may be applied for low reflection loss
Implementation Method 4
One or multiple high-reflective (HR) coating (also called mirror coatings) may be used to achieve this by reflecting converted light
Implementation Method 5
A metallic coating may be applied (optionally on another coating). This may reduce leak of emission light at a large angle to the surface of the solid-state light conversion material
Data Source
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AI summary
A light converter (200) comprises: a solid-state light conversion material (201) that generates emission light from excitation light incident on its surface; a filler layer (230, 240) on the surface of the solid-state light conversion material (201); and an optical coating (220, 250) on the filler layer. The optical coating (220, 250) may be a thin film, such as an anti-reflective coating (220) and/or a high-reflective coating (250). A metallic coating (260) may additionally be provided. The light converter (200) may be used for an optical device, such as a phosphor wheel or automotive headlight.