Active Metal-Dielectric Photonic Crystals

Metal-dielectric photonic crystals (MDPCs) are periodic structures realized by vertically stacked metallic microcavities, resulting in alternating layers of semi-transparent metals and relatively thick dielectrics. Unlike plasmonic metamaterials, MDPCs rely on the hybridization of the underlying microcavity states rather than the coupling of surface plasmons, which produces multiple optical Bloch states arranged in photonic bands. This hybridization can be accurately described using coupled-mode theory, exactly analogous to the formation of molecular orbitals and the electronic energy bands in atomic crystals.<br/><br/>The high conductivity and carrier density of the metallic layers makes MDPCs ideal for active photonic devices and enables a significant reduction in physical thickness due to the high reflectivity at the metal-dielectric interfaces. We have recently exploited this to develop organic light-emitting diodes (OLEDs) that directly express the photonic band structure in their electroluminescence spectrum in the weak coupling regime. In this presentation, we discuss the theoretical foundations of MDPCs using quasi-normal mode formalism and coupled-mode theory. We apply this theory to demonstrate control over the emission spectrum of electrically-driven MDPC OLEDs in both simple and binary crystal configurations by varying the density-of-states and introducing a photonic band gap.