Nonlocal Dispersion and Intermediate Layer Effects in Insulator-Insulator-Metal Plasmonic Waveguides

This study derives the nonlocal dispersion relation of surface plasmon polaritons (SPPs) in insulator-insulator-metal (IIM) plasmonic waveguides based on the generalized nonlocal optical response (GNOR) model. The GNOR model incorporates the effects of quantum pressure and electron diffusion dynamics in metals, providing a more accurate theoretical framework compared to the conventional local response approximation (LRA). The results reveal that nonlocal effects induce a frequency blueshift and increased propagation loss for SPPs. Furthermore, the study systematically investigates the influence of intermediate layer thickness and dielectric constant on the propagation characteristics of SPPs. Both parameters are shown to significantly affect mode localization, group velocity, and propagation loss. This work offers valuable theoretical guidance for the optimization of nanophotonic devices.