Editorial on special issue “The 11th International Conference on Surface Plasmon Photonics (SPP11)”

Plasmonics has a long history, and fundamental research has been extensively conducted across a wide range of topics.Similarly, nearly three decades have passed since the first proposal and realization of metamaterials.Today, plasmonics and metamaterials are no longer pursued only as subjects of fundamental science or as "technologies of the future"; they have evolved into practical technologies for which concrete applications are being widely investigated, optimized, and implemented.Participants shared their latest research findings and discussed future directions in the rapidly evolving field of plasmonics, nanophotonics, and metamaterials.The conference covered both the fundamental principles and emerging applications of plasmonics, nanophotonics, and metamaterials, featuring keynote and invited presentations from internationally recognized leaders, along with contributed oral and poster sessions.This special issue of Nanophotonics brings together selected contributions from SPP11 and related research presented at the conference.It highlights the latest advances in plasmonics, nanophotonics, and metamaterials, reflecting not only the remarkable scientific and technological progress achieved by the community, but also the expanding frontiers and interdisciplinary opportunities that continue to shape this dynamic field.J. Ahn et al.[1] contribute the memorial paper for Professor Dai-Sik Kim, who was general chair of SPP5 and passed away on November 11th, 2024, and reviews the scientific contributions and vision of Prof. Kim in near-field optics, plasmonics, and THz spectroscopy.Authors also highlight major breakthroughs and their impact through personal accounts from collaborators.Xie et al. [2] reveal hidden meso-chirality in plasmonic nanoparticles emerging from cancellation between absorption-and scattering-based chiral responses.Authors further show that such concealed chirality can be strong and broadband in realistic nanostructures.An et al. [3] show that adjusting the wavelength and polarization of excitation light allows controlled generation of plasmonic topological quasiparticles in a metasurface.Authors also visualize their distinct near-field textures, confirming tunable skyrmion and meron formation.Chaves et al. [4] present a hydrodynamic model that captures nonlocal magnetoplasmon behavior in anisotropic 2D materials.Authors further show how nonlocal and quantum effects reshape their dispersion and optical conductivity.Biehs and Bondarev [5] identify topological singularities in transdimensional plasmonic films that strongly influence their reflection coefficients.