Nonlocal dispersion of anisotropic MIM plasmonic waveguides within the GNOR framework

The dispersion relation of an anisotropic metal–insulator–metal (MIM) plasmonic waveguide is derived within the framework of the generalized nonlocal optical response (GNOR) model. The GNOR model extends the hydrodynamic Drude model (HDM) by introducing an electron diffusion term, thereby providing a more accurate description of nonlocal electron dynamics in metals. Numerical results indicate that increasing the diffusion constant d enhances nonlocal effects, leading to a blue shift of the modal frequency and a reduction in the propagation length. The anisotropic parameters further exert a pronounced influence on the dispersion characteristics, where variations in the principal-axis rotation angle and anisotropy ratio modify both the modal frequency and propagation behavior. These findings elucidate the coupled influence of nonlocality and anisotropy on plasmonic waveguide performance and provide theoretical guidance for the design of tunable plasmonic devices. • The nonlocal dispersion relation of anisotropic MIM plasmonic waveguides is derived within the GNOR framework. • Electron diffusion enhances nonlocal effects, leading to a blue shift and stronger damping. • Dielectric anisotropy allows tunable modulation of modal frequency and propagation length.