Dynamically Tunable Singular States Through Air-Slit Control in Asymmetric Resonant Metamaterials

This study presents a novel method for dynamically tuning singular states in one-dimensional (1D) photonic lattices (PLs) using air-slit-based structural modifications. Singular states are isolated resonance radiations generated by breaking symmetry, which produces various spectra from the interplay between resonance modes and background radiation. By breaking symmetry in 1D PLs with air slits, effective control of resonance positions is demonstrated, enabling dual functionalities including narrowband band pass and notch filtering. These singular states originate from asymmetric guided-mode resonances (aGMRs), which can be interpreted by analytical modeling of equivalent slab waveguide. Furthermore, multiple air-slits significantly enhance spectral tunability by inducing multiple folding behavior in the resonance bands. This approach facilitates effective manipulation of optical properties through simple adjustments of air-slit displacements. This work provides great potential for designing multifunctional photonic devices with advanced metamaterial technologies.