Flexible wavefront manipulation using exceptional points generated by non-interleaved metasurfaces

Precise modulation of the optical wavefront is the main way in which metasurfaces act, and the exceptional point (EP) topological phase provided by non-Hermitian metasurfaces offer an additional degree of freedom for the metasurface design. Here, we design an F-shaped non-interleaved metasurface whose unit cell consists of two basic resonators – a nanowire and a split ring resonator (SRR). By adjusting the strength and coupled-mode of these two resonators, the 2π phase accumulation enclosing the EP, the asymmetric transport properties, and the evolution of wavelength-dependent EP are observed. These properties allow for flexible wavefront manipulation in polarization, amplitude and wavelength dimensions. We simulate and demonstrate a spin-decoupled metasurface hologram, a dual-wavelength decoupled metasurface hologram, as well as a dual-wavelength metasurface for near-field nanoprinting and far-field holography. Non-Hermitian topological metasurfaces can be conveniently combined with other wavefront manipulation mechanisms, showing promising applications in the design of nanophotonic devices.