Symmetry Breaking and Mie-tronic Supermodes in Nonlocal Metasurfaces

Breaking symmetry in Mie-resonant metasurfaces challenges the conventional view that it weakens optical confinement. Within the Mie-tronics framework, we show that symmetry breaking can instead enhance light trapping by strengthening in-plane nonlocal coupling pathways. Through diffraction and multiple-scattering analyses, we demonstrate that diffractive bands and Mie-tronic supermodes originate from the same underlying Mie resonances but differ fundamentally in physical nature. Finite arrays exhibit Q-factor enhancement driven by redistributed radiation channels, reversing the trend predicted by infinite-lattice theory. We further show that controlled symmetry breaking opens new electromagnetic coupling channels, enabling polarization conversion in nonlocal metasurfaces. These findings establish a unified wave picture linking scattering and diffraction theories and outline design principles for multifunctional metasurfaces that exploit nonlocality for advanced light manipulation, computation, and emission control.