Nonlocal Metasurfaces

In this talk, we present and discuss our recent advances on metasurfaces based on highly nonlocal features, stemming from long-range resonant interactions and lattice phenomena. Different from conventional metasurface approaches, engineered nonlocality offers tailored spectral control, both temporally and spatially, ideal for signal processing applications, and combined with enhanced light-matter interactions. We achieve these features by combining quasi-bound states in the continuum with geometric phase variations in engineered metasurfaces, tailoring at will the supported eigenwaves. The resulting metasurfaces support ultrasharp responses selective to the impinging wave properties, effectively realizing ultrathin transparent films that highly reflect light only when illuminated by selected polarization, frequency and wavefront spatial distribution of choice. The demonstrated wavefront selectivity of nonlocal metasurfaces opens exciting opportunities for augmented reality, secure communications, thermal emission management, optical modulators and enhanced light-matter interactions for nonlinear and quantum optics.