Flexible engineering of circular dichroism enabled by chiral surface lattice resonances

Abstract

Engineering the chiroptical responses of artificial nanostructures is vital for realizing applications in the fields of optical devices, enantioselective separation, and bio-sensing. Here, by utilizing the nano-kirigami based meta-molecule arrays, the flexible engineering of circular dichroism (CD) is achieved in the near-infrared wavelength region by the excitation of chiral surface lattice resonances (SLRs). It is found that the chiral SLRs can be flexibly tailored by a tiny structural perturbation. As a result, the wavelength, intensity, and sign of CD peak/dip can be abruptly engineered. Specifically, a CD peak with the value of +0.44 is evolved into a CD dip with an intensity of -0.66 when the etching silt length of the meta-molecules is simply decreased by 190 nm. Importantly, such CD reversal is experimentally demonstrated with the nano-kirigami method without requiring the inversion of geometric chirality. Moreover, it is found that the asymmetric dielectric environment around the meta-molecules can significantly suppress the chiral SLRs, providing an insightful understanding of the chiral SLR. Such flexible tailoring of the CD with chiral SLRs paves a versatile way toward the manipulation of chiral light-matter interactions and chiroptical functional devices.