Local circular polarizations in nanostructures induced by linear polarization via optical near-fields

TL;DR

This paper reveals that linear polarized light induces local circular polarizations in nanostructures due to near-field interactions, with implications for understanding and designing nanoscale optical polarization control.

Contribution

It introduces a theoretical framework explaining how layout-dependent phase differences lead to circular polarization in nanostructures, advancing the understanding of optical near-field properties.

Findings

Circular polarizations are induced at resonant wavelengths.

The phase difference between susceptibilities causes circular polarization.

The study provides a general theoretical approach for nanoscale polarization control.

Abstract

We previously reported [Naruse, et al. Sci. Rep. 4, 6077, 2014] that the geometrical randomness of disk-shaped silver nanoparticles, which exhibit high reflection at near-infrared wavelengths, serves as the origin of a particle-dependent localization and hierarchical distribution of optical near-fields in the vicinity of the nanostructure. In this study, we show that the induced polarizations are circular, particularly at resonant wavelengths. We formulate optical near-field processes between nanostructures, accounting for their polarizations and geometries, and attribute circular polarization to the layout-dependent phase difference between the electrical susceptibilities associated with longitudinal and transverse-electric components. This study clarifies the fundamental optical properties of random nanostructured matter and offers generic theoretical concepts for implementing nanoscale polarizations of optical near-fields.