Photofabrication of Chiral Plasmonic Nanostructure Arrays

Chiral Au−PbO₂ nanostructure arrays were fabricated via nanosphere lithography and plasmon-induced charge separation. The arrays exhibit circular dichroism based on multipole modes of localized surface plasmon resonance. The handedness of the arrays can be controlled by circularly polarized light used for the nanostructure fabrication.

Abstract

Chiral plasmonic nanostructures can be potentially applied to chiroptical materials and devices, as well as sensors for chiral molecules. When those are applied to metasurfaces or metamaterials, those would be appropriately oriented and aligned. We therefore prepared arrays of chiral plasmonic nanostructures on the basis of bottom-up, self-assembling methods. A triangular Au nanoplate array as an achiral precursor was prepared on a TiO₂-coated substrate by nanosphere lithography. The array was irradiated with right- or left-circularly polarized light (CPL) in a solution containing Pb²⁺ for site-selective deposition of PbO₂ in a chiral geometry by plasmon-induced charge separation. The well-aligned Au−PbO₂ nanostructure array thus obtained exhibits circular dichroism, and the handedness of the array can be inverted by changing the rotation direction of the irradiated CPL.

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