Imaging through Fano-resonant dielectric metasurface governed by quasi-BIC

Fano resonance has raised great attention in nanophotonics attributing to its unique properties.In this work, we study the imaging function of Fano-resonant silicon metasurfece governed by quasi-bound states in the continuum (BICs). First, by breaking the in-plane symmetry of nanodisks, a symmetry-protected quasi-BIC is excited with the emergence of a sharp Fano resonance. The near field distributions, multipole contributions and radiation patterns of the metasurface are performed to uncover the mechanism and characteristics of this resonance. In addition, we investigate the imaging function of this Fano-resonant metasurface assisted by phase-change material Ge_2Sb_2Te_5(GST). Through selective modification of different units from a-GST to c-GST, the produced transmitted image well reconstructs the target letter. Our finding may provide a route to achieve efficient metasurface-based imaging and fast spatial modulations.