Roadmap on plasmonic filters waveguides for photonics integrated circuits

Plasmonic filters have emerged as transformative components in integrated photonics, offering unprecedented control of light at the nanoscale. By exploiting surface plasmon polaritons (SPPs) at metal–dielectric interfaces, these filters enable the design of ultracompact, high-efficiency devices capable of operating beyond the diffraction limit. This review presents a comprehensive roadmap of recent advances in plasmonic filter technology, with emphasis on waveguide-integrated configurations and diverse resonator geometries—including square, circular, triangular, and hybrid structures. Key innovations such as the incorporation of electro-optic and thermo-optic materials, nanodisk-based architectures, and multi-band filtering strategies are critically analyzed. Moreover, the transition toward alternative materials like titanium nitride and graphene is explored as a pathway to overcome the limitations of noble metals.