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Low-energy Cathodoluminescence for OxyNitride Phosphors
Published on: November 15, 2016
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Light extraction from luminescent light sources and application to monolithic ceramic phosphors
Optics Letters
|July 1, 2014
Summary
Improving light extraction from LEDs and phosphors requires enhancing radiance via cavity effects and using scattering or diffraction to couple trapped light into propagating modes. This optimizes light output for macroscopic sources.
Area of Science:
- Optics and Photonics
- Materials Science
Background:
- Light extraction efficiency is crucial for LED and phosphor performance.
- Total-internal-reflection (TIR) limits light escape from high-index materials.
Purpose of the Study:
- To extend light extraction theorems for luminescent devices.
- To identify key mechanisms for efficient light extraction.
Main Methods:
- Derivation of an extended light extraction theorem.
- Application of radiation transport calculations.
- Analysis of geometric and diffractive surface structures.
Main Results:
- A generalized bound for light extraction is established.
- Cavity effects and surface structures (scattering/diffraction) are shown to be essential.
- TIR modes must be coupled to propagating modes for efficient extraction.
Conclusions:
- Efficient light extraction from LEDs and phosphors necessitates a synergistic approach.
- Cavity enhancement and surface-based mode coupling are critical design parameters.
- The findings are applicable to macroscopic luminescent sources.
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