Multi-channel filtering and dynamic modulation of multiple Fano resonances in all-dielectric metasurfaces

Abstract

In nanophotonics, achieving dynamic reconfiguration and multipole resonance in dielectric metasurfaces is crucial for developing high-performance spectral filters. In this work, we propose a tunable all-dielectric metasurface based on the bound states in the continuum (BICs) mechanism, designed as a multi-channel optical filter that can cover different near-infrared communication bands. It exhibits high transmittance, narrow bandwidth, dynamic tunability, and good angle robustness. Using the quasi-BIC mechanism, we demonstrated that breaking structural symmetry could effectively excite multiple sharp Fano resonances, enabling the filter to switch between two and four channels flexibly. By analyzing the electromagnetic field distribution at different transmission peaks, the contribution of different electromagnetic excitations to Fano resonance was discussed. Additionally, the dynamic tuning of multiple Fano resonances was achieved by adjusting the refractive index of the phase-change material Ge₂Sb₂Te₅ (GST), while internal tuning was achieved by optimizing the structural parameters. The design also exhibits good angle robustness at small oblique incidence angles (<25°). Therefore, this design demonstrates significant advantages in terms of feasibility and practicability, which may provide an essential reference for designing and applying future high-performance multi-channel filters.