Ultraviolet ultranarrow second-order magnetic plasmon induced reflection of lifted 3D metamaterials for slow light and optical sensing

Abstract

We theoretically demonstrate the ultraviolet (UV) high-order magnetic plasmon induced reflection (PIR) by lifting metamaterials consisting of three-dimensional aluminum split-ring resonators (3D-AlSRRs) with the effect of substrate being reduced. The strong plasmonic coupling between the second-order magnetic plasmon (2nd MP) of the lifted 3D-AlSRRs and the surface plasmons polaritons propagated on the Al substrate is achieved and leads to an ultranarrow PIR with linewidth of 4.6 nm in the UV range. The UV PIR effect is theoretically explained by an analytical Fano coupling model. In addition, the lineshape and position of the UV 2nd MP induced PIR can be artificially adjusted through varying the geometric parameters. The maximum of the group index of about 120 is achieved in the UV range. In addition, the sensitivity (S) and figure of merit (FoM) of the lifted 3D-AlSRRs are obtained to be 240 nm/RIU and 52, respectively. Our designed 3D metamaterials open a new path for the designing of multi-functional devices for such as slow-light and high sensitive optical sensor in the UV range.