Phosphor Waveguide Illumination Device Light Extraction
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Solution Overview
Problem
Existing illumination systems face challenges in achieving high light extraction efficiency from luminescent materials, particularly due to total internal reflection and light emission in undesirable directions, which reduces system efficiency.
Innovation Solution
The use of a transparent phosphor optically coupled with a flat waveguide and a reflector, where the exit surface of the illumination device is larger than any single light emitting surface of the phosphor, and the reflector redirects optical radiation to enhance light extraction, increasing the effective escape surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If phosphor is pumped from one surface and light is extracted from the opposite surface, then light extraction is achieved, but total internal reflection causes light to be emitted in all directions including back toward the pump source, reducing system efficiency
Solution Approach 1:
The patent introduces a waveguide structure that adds a spatial dimension to light management. By confining and guiding light through the waveguide layer, the system controls light propagation paths in three-dimensional space, enabling efficient extraction from the exit surface while preventing backward emission toward the pump source.
Solution Approach 2:
The waveguide acts as an intermediary between the phosphor and the exit surface. It receives light from the phosphor, manages its propagation through total internal reflection and guided modes, and directs it toward the exit surface, thereby mediating the light extraction process to achieve high efficiency.
2Ease of operation
If a waveguide is used to guide light from phosphor to exit surface, then light extraction efficiency is improved, but device complexity increases due to additional optical components
Solution Approach 1:
The waveguide layer serves multiple functions simultaneously: it guides light from the phosphor to the exit surface, provides structural support, and can be integrated with the packaging layer. This multi-functionality reduces the need for separate dedicated components, thereby managing complexity while maintaining high light extraction efficiency.
Solution Approach 2:
The patent merges the waveguide function with the existing phosphor layer and packaging structure. By combining light guiding, structural, and protective functions into an integrated layered system, the design achieves high efficiency without proportionally increasing device 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
This configuration allows for significantly higher light emission from a single surface, potentially tripling the light output from the surface opposite to the pump source, with extraction efficiencies approaching 100% in laser pump systems and maintaining high efficiency with LED sources.
Implementation Method 1
a phosphor being optically coupled to a waveguide... emitting optical radiation directed to the phosphor... which is adapted for emitting phosphor light
Implementation Method 2
In remote laser lighting concept, typically phosphor is pumped from one of the surfaces and the generated light by the phosphor needs to be extracted from the opposite surface. In a transparent phosphor total internal reflection, TIR for short, takes place.
Implementation Method 3
the reflector is adapted for reflecting at least a part of the optical radiation emitted from the illumination device by a surface different from the exit surface of the illumination device
Data Source
Figure 1~2
Figure 3a~3b
Figure 3c~3e
AI summary
The invention relates to an illumination device and a method adapted for illuminating applications. The illumination device (5) with a phosphor (1) comprising at least one light emitting surface which is adapted for emitting phosphor light in a predefined solid angle, a light source (2) being adapted for emitting optical radiation directed to the phosphor (1), a waveguide (3), and a reflector (4), wherein the phosphor (1) is optically coupled to the waveguide (3), the exit surface of the illumination device (5) from which light is emitted is larger than any single light emitting surface of the phosphor (1), and the reflector (4) is adapted for reflecting at least a part of the optical radiation emitted from the illumination device (5) by a surface different from the exit surface of the illumination device (5). In this way, a high light extraction efficiency from a single surface of a luminescent material and at the same time a high quantum efficiency of the illumination device is achieved.