Advances on Nonlocal Metasurfaces

In this talk, I will present and discuss our recent advances on metasurfaces based on highly delocalized modes, stemming from long-range resonant interactions and lattice phenomena. Different from conventional metasurface approaches, engineered nonlocality offers tailored spectral control, and at the same time can be tailored in space with large resolution using geometric phase concepts. Their response is ideal for imaging and signal processing applications, and to enhance 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. In particular, in the talk we demonstrate our recent experimental demonstrations on highly efficient signal processing metasurfaces for polarization imaging, thermal metasurfaces, and other applications of these phenomena.