مشخصات پژوهش

In this work, a dual-mode hybrid photonic–plasmonic platform was designed, fabricated, and systematically characterized. The structure consists of a TiO₂ two-dimensional monolayer inverse opal (2D MIO) decorated with Au nanoparticles (AuNPs) via sputtering followed by thermal annealing. This fabrication strategy enabled spatially selective formation of quasi-spherical AuNPs predominantly within the bowl-shaped cavities, along with triangular-shaped AuNPs located at the interstitial junctions of the inverse opal lattice. Morphological characterization using field-emission scanning electron microscopy (FESEM) confirmed the formation of a highly ordered hexagonal TiO₂ 2D MIO and the successful incorporation of AuNPs with distinct spatial distributions. Optical characterization by UV–Vis spectroscopy (extinction mode) revealed a combined photonic–plasmonic response arising from the periodic TiO₂ architecture and the embedded Au nanostructures. A broad spectral feature in the ~ 530–550 nm range is attributed to Bragg diffraction of the TiO₂ 2D MIO coupled with collective and lattice-modified plasmonic excitations of cavity-confined AuNPs. In addition, a distinct band near ~ 740 nm originates from anisotropic triangular-shaped AuNPs and their coupling effects within the high-refractive index TiO₂ environment. Finite-difference time-domain (FDTD) simulations reproduce the main spectral features and provide insight into the electromagnetic response of the system, revealing strong electric-field localization at cavity interfaces and nanoparticle junctions. The combined photonic–plasmonic interaction within this architecture demonstrates tunable optical behavior governed by geometry, periodicity, and dielectric environment, suggesting potential for future exploration in optical sensing and surface-enhanced spectroscopic applications.