High-Q Metasurface Via Quasi-Bic Resonance for Optical Differentiation

We design a metallic metasurface supporting high$Q$quasi-bound states in the continuum (quasi-BIC) by tuning the spacing and displacement of split-ring resonators. Simulations and experiments confirm the coexistence of bright SPP and dark quasiBIC modes in the terahertz regime. By leveraging its sharp highpass filtering properties in the Fourier domain, we demonstrate its application in spatial differentiation for edge detection. This work provides a new approach to integrating high-Q metasurfaces with optical analog computing for ultra-compact, high-speed signal processing.