Tunable Plasmonic Chirality Revealed by Helical Heteterostructure Metamaterials

In this study, by using the glancing angle deposition technique, subsequent and repeated depositions of silicon(Si) and silver(Ag) lead to nanometer-dimension sub-chiral segments, and thus, we successfully fabricated spatially coherent, highly porous, super lattice-type helical heterostructure thin films. We theoretically and experimentally investigate the chiro-optical properties of this new type of plasmonic metamaterials via finite element modeling calculations and Mueller matrix spectroscopic ellipsometry method, respectively. The systematic changes in the morphology of helical structures by incorporating the plasmonic subsegments reveal an extra-ordinary chiro-optical response with fine spectral tunability over the entire visible spectral range into the ultra-violet.