Toroidal electric dipole enabled chiral surface lattice resonances in stereo propeller metasurfaces

Abstract

Surface lattice resonances (SLRs) are the coherent collective interactions between periodically arranged nanoparticles, which are generally considered to be formed by the resonant electric dipole, magnetic dipole, or electric quadrupole moments of a single nanoparticle coupled with the Rayleigh anomaly (RA). Here we reveal the first observation of the chiral SLRs that are formed by the coupling of the chiral toroidal electric dipole (TED) moment and RA mode through the theoretical design and experimental fabrication of a nano-kirigami based propeller metasurface. By engineering the rotational symmetry of the propeller, e.g., from C2 (C3) symmetry to C4 symmetry, we find that the electric dipole (electric quadrupolar) chiral SLRs have evolved into the TED associated chiral SLRs. Furthermore, it is found that the excitation amplitude of the TED moment can be tailored by controlling the stereo twisted height of the propeller and the spin of the incident light. Finally, the chiral TED moment enhanced circular dichroism is verified in the near-infrared wavelength region. Our study provides an effective yet simple scheme to manipulate the TED-dependent chiral SLRs, paving the way toward exploring the unconventional physical properties of TED and advanced chiroptical physics.