Tailoring the chiro-optical response of Si-Ag/Au chiral heterostructure thin films fabricated by glancing angle deposition technique

Chiro-optical response of subwavelength scale nanostructures have been the subject of many research projects such as bio-sensors, topological insulators, and photonic integrated circuit designs. [1] In this study, by using glancing angle deposition technique, subsequent and repeated depositions of silicon(Si) and gold(Au)/silver(Ag) lead to nanometer-dimension sub-chiral segments, and thus, we successfully fabricated spatially coherent, highly porous, super lattice type chiral heterostructure (CHS) thin films. We incorporated the transmission mode Mueller matrix spectroscopic ellipsometry technique with finite element modeling environment in order to investigate the chiro-optical properties of this new type plasmonic metamaterials. Interestingly, Au/Ag sub-chiral segments in CHS result in the emergence of multiple plasmonic modes which can be tunable depending on the Au/Ag-Si ratio in a single turn. Unlike the other studies [2,3] which employs periodic nanostructures made up of single type material, we observed extraordinary optical activity in our fabricated CHS thin films.
References:
[1] Hentschel, Mario, et al., Science advances3.5, e1602735, (2017).
[2] Schulz, Matthias, et al., Nature communications 9.1, 2413, (2018).
[3] Lee, Hye-Eun, et al., Nature 556.7701, 360, (2018).