Dielectric Wavelength Filter for LED Light Extraction
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Solution Overview
Problem
Traditional white LED modules suffer from optical loss due to light being emitted in all directions and re-entering the device, leading to reduced light emitting efficiency, as the light converted by fluorescent materials is absorbed inside the device.
Innovation Solution
A light emitting device package with a sub mount, a light emitting device, a dielectric layer, and a fluorescent layer, where the dielectric layer has multiple layers with different refractive indices to transmit short wavelengths and reflect long wavelengths, preventing optical loss by using a selective wavelength filter between the light emitting device chip and the fluorescent layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fluorescent material is applied on the edge of a blue LED to convert light, then the light can be converted to different wavelengths, but the converted light is emitted in all directions and re-entering the device is absorbed, causing optical loss and deteriorating light emitting efficiency
Solution Approach 1:
A dielectric layer is introduced as an intermediary component between the light emitting device and the fluorescent layer. This dielectric layer selectively transmits light of the first wavelength (e.g., blue light) while reflecting light of the second wavelength (e.g., yellow converted light), preventing the converted light from re-entering and being absorbed by the light emitting device, thus reducing optical loss while maintaining wavelength conversion capability
Solution Approach 2:
The dielectric layer is designed with specific optical properties (selective transmission and reflection at different wavelengths) applied locally at the interface between the light emitting device and fluorescent layer, creating a localized optical management zone that directs light paths without affecting the overall device 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 configuration effectively increases reflectivity and transmittance, ensuring that short wavelengths are extracted externally while long wavelengths are reflected, enhancing light extraction efficiency and achieving a higher color rendering index.
Implementation Method 1
the dielectric layer includes a plurality of layers having at least two different refractive indices, that transmits the light of the first wavelength and reflects the light of the second wavelength
Implementation Method 2
the dielectric layer includes a plurality of layers having at least two different refractive indices, that transmits the light of the first wavelength and reflects the light of the second wavelength
Implementation Method 3
a fluorescent layer on the dielectric layer, and configured to convert the light of the first wavelength into light of a second wavelength
Data Source
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AI summary
A light emitting device package includes a sub mount; a light emitting device on the sub mount, and configured to generate light of a first wavelength; a dielectric layer disposed on the sub mount; and a fluorescent layer on the dielectric layer, and configured to convert the light of the first wavelength into light of a second wavelength, wherein the dielectric layer includes a plurality of layers having at least two different refractive indices, that transmits the light of the first wavelength and reflects the light of the second wavelength.