Beam steering with dielectric metalattices

We study optical wave manipulations through high-index dielectric metalattices in both diffractionless metasurface and diffractive metagrating regimes. It is shown that the collective lattice couplings can be employed to tune the excitation efficiencies of all electric and magnetic multipoles of various orders supported by each particle within the metalattice. The interferences of those adjusted multipoles lead to highly asymmetric angular scattering patterns that are totally different from those of isolated particles, which subsequently enables flexible beam manipulations, including perfect reflection, perfect transmission and efficient large-angle beam steering. The revealed functioning mechanism of manipulated interplays between lattice couplings and multipolar interferences can shed a new light on both photonic branches of metasurfaces and metagratings, which can potentially inspire many advanced applications related to optical beam controls.