Single-pass and omniangle light extraction from light-emitting diodes using transformation optics

Area of Science:

• Optoelectronics
• Photonics
• Materials Science

Background:

• Light-emitting diodes (LEDs) suffer from internal light loss due to total internal reflection.
• Efficient light extraction is crucial for enhancing LED performance and reducing energy waste.

Purpose of the Study:

• To develop a novel light-extraction approach for LEDs.
• To achieve single-pass and omniangle outcoupling of light.
• To design a compact and wavelength-independent light extractor.

Main Methods:

• Utilized transformation optics to design a graded-index structure.
• The structure transitions from the LED exit facet to a low refractive index region (air).
• Applied index and geometry truncation for beam expansion while preserving efficiency.

Main Results:

• Demonstrated a feasible graded-index structure for efficient light extraction.
• The approach is wavelength-independent, excluding material dispersion.
• The extractor is geometrically compact, suitable for pixelated LEDs.
• Achieved beam-expanding functionality without compromising outcoupling efficiency.

Conclusions:

• The proposed light-extraction method offers a significant advancement for LED technology.
• The compact and efficient design is ideal for next-generation pixelated LED applications.
• This approach paves the way for improved LED brightness and energy efficiency.