Controlling the Band Structures in Defect-Enhanced Metal-Dielectric Photonic Crystals*

Through the periodic arrangement of metal and dielectric films, one-dimensional photonic crystals can be designed to manipulate the propagation of light. This work explores the manipulation of the photonic band structure in metal-dielectric photonic crystals (MDPCs) through defect engineering within stacked organic semiconductor microcavities. By introducing aperiodic crystal defects into the cavity layers, we demonstrate both theoretically and experimentally how these defects create localized mid-gap states and impact the transmission properties of the photonic crystal. Our transfer matrix simulations and experimental results reveal that defect size and location within the cavity stack offer a precise control mechanism over the band structure, creating well defined mid-gap states and enabling the selective enhancement or suppression of resonance between adjacent cavities. This tunability introduces new possibilities for passive optical filters and optoelectronic devices, including enhanced control over emission spectra in OLED-based systems. Our findings establish a foundation for novel approaches in spectral manipulation and field localization, opening pathways to advanced applications in photonic device engineering.