Intrinsically or extrinsically reconfigurable chirality in plasmonic chiral metasurfaces

In this work, we theoretically present a reconfigurable plasmonic chiral metasurface based on a sandwiched metal-insulator-metal structure, which can strongly, spin-selectively absorb circularly polarized light. Through finite-difference time-domain simulation, the absorption of left- or right-handed circularly polarized light can reach nearly 100% at the resonant position, and the magnitude of the circular dichroism can be 80%, which is larger than most of the previously reported value. This strong chiroptical effect originates from plasmonic resonances induced by the incident circularly polarized light. Furthermore, the proposed plasmonic chiral metasurface is able to be reconfigurable by either changing its intrinsic or extrinsic chirality, which can be numerically confirmed by the change of the sign and magnitude of the CD. Such a reconfigurable plasmonic chiral metasurface could find many potential applications in chirality detection/sensing, polarimetric imaging, spin-orbit communications, etc.