Double embedded photonic crystals for extraction of guided light in light-emitting diodes

Light-emitting diodes (LEDs) were fabricated in gallium nitride with two embedded photonic crystals (PhCs), creating a waveguide with a highly confined, strongly excited, and well-extracted fundamental mode. This structure improves upon previous PhC LED designs by reducing the extraction length of the fundamental mode and establishing a path to designs with very low absorption losses. Optical output was measured with angular-resolved electroluminescence. The extraction length of the fundamental mode was measured to be 21–39 μm along the PhCs’ Γ-M directions, which is much shorter than values reported for single-PhC devices. This structure opens the way to more efficient LEDs and lasers.