Hybrid Plasmonic Twisted L-Shaped Metamaterials: A New Pathway to Tailorable Optical Chirality

We introduce a new class of plasmonic hybrid twisted L-shaped (nanoboomerang) metamaterials (MMs) in which silicon (Si) nanocolumns are sub-segmented and plasmonic silver (Ag) nanosegments are integrated, forming periodic Si–Ag interfaces that enable active control of optical chirality. By tuning the Ag fill fraction and segment geometry, we demonstrate precise spectral tailoring of chiroptical response. Mueller-matrix generalized spectroscopic ellipsometry is employed to distinguish intrinsic and extrinsic contributions to circular dichroism, providing a robust method to eliminate artifacts associated with linear anisotropy. The presented MM system also enables the experimental extraction of both intrinsic (originates from the meta-atom’s twisted, mirror-asymmetric geometry) and extrinsic (arises collectively through array symmetry) chirality regimes[1,2]. Finite element modeling further reveals that the engineered metal–dielectric junctions lead to strong electromagnetic coupling, inducing multipole interference and broadband enhancement of the chiroptical response.

Reference

[1]G. Zhu et al.,ACSAppl.Opt.Mater.2,1209,(2024).

[2]U. Kilic et al.,Nat.Commun.15,3757(2024).