Light extraction by directional sources within optically dense media.

Area of Science:

• Optoelectronics
• Photonics
• Semiconductor Devices

Background:

• Light extraction efficiency (LEE) is typically measured against isotropic radiators in dielectric media.
• This standard metric is often inaccurate for photonic devices with directional light sources.

Purpose of the Study:

• To derive exact solutions for LEE from directive sources near planar dielectric boundaries.
• To account for Fresnel reflections at the interface for accurate LEE calculations.
• To provide a baseline for validating numerical simulations and source models.

Main Methods:

• Analytical derivation of LEE for directive radiating sources.
• Inclusion of Fresnel reflection effects at the dielectric interface.
• Analysis of four source models: isotropic radiator, Hertzian dipoles (parallel/perpendicular), and Lambertian scatterer.

Main Results:

• Exact LEE solutions were derived for directive sources, improving upon isotropic models.
• Fresnel reflections were quantified, showing negligible impact with large escape cones.
• LEE reduction of 20% or more was observed when the critical angle is below 25°.

Conclusions:

• The derived exact solutions offer a more accurate method for LEE assessment in directional photonic devices.
• These results are crucial for validating computational models and understanding baseline performance.
• The study highlights the significant impact of Fresnel reflections on LEE in specific material systems.