Red emission enhancement via strong coupling between photonic–plasmonic band states in InGaN/GaN honeycomb nanocolumn plasmonic crystals

Abstract

InGaN-based light-emitting diodes (LEDs) exhibit excellent emission efficiency in the blue spectral region but experience severe degradation of external quantum efficiency in the red region, primarily due to lattice strain and increased defect density. To address this limitation, we introduced surface plasmon polaritons into InGaN/GaN nanocolumn (NC) arrays arranged in a honeycomb lattice to enhance red-light emission. Deposition of Ag films on the photonic crystal NCs generated plasmonic crystals that allowed precise control of photonic–plasmonic band interactions. Angle-resolved photoluminescence measurements combined with electromagnetic field analysis revealed that strong coupling occurs when photonic and plasmonic field modes are spectrally and spatially matched. Rabi splitting was observed due to the strong coupling between photonic and plasmonic band states, and a 9.6-fold enhancement in red emission was achieved through the combined effects of strong and weak coupling. This controllable strong coupling between photonic and plasmonic band states provides a promising approach for overcoming the intrinsic efficiency limitations of InGaN-based red LEDs while simultaneously enhancing their optical functionality.