Star-shaped nanostructure-based multifunctional chiral metasurface for near-infrared wavelengths

TL;DR

This paper introduces a novel star-shaped nanostructure-based chiral metasurface operating in the near-infrared, demonstrating multifunctional optical properties including high circular dichroism, polarization conversion, and enantiomer detection.

Contribution

The work presents the first design of a multifunctional chiral metasurface with star-shaped antennas for NIR applications, combining multiple optical functionalities in a compact platform.

Findings

Maximum circular dichroism of 0.7 at 971.5 nm

Asymmetric transmission of 0.92 at 1020 nm

Effective enantiomer differentiation in sensing applications

Abstract

Here, we reported, for the first time, a chiral metasurface with multifunctional capabilities tailored for the near-infrared (NIR) wavelength range, garnering tremendous interest in applications such as optical communication and chiral sensing. The structure comprised star and bar-shaped silver antennas immersed in SiO2. In computational simulations based on the finite-difference time-domain method, the proposed architecture yielded a maximum circular dichroism of 0.7 at 971.5 nm wavelength and a maximum asymmetric transmission under linearly polarized excitation of 0.92 at 1020 nm wavelength. Moreover, this multifunctional structure manifested near-perfect cross-polarization conversions for both linear and circular polarizations, as well as linear to circular and elliptical polarization conversion effects at different bands within the NIR spectral region. The enhanced light-matter interaction of the proposed structure was utilized to detect and differentiate two enantiomers of 1,2-propanediol, yielding excellent chirality sensing capability. As a multifunctional compact chiral platform, the proposed structure is expected to find direct applications in integrated and miniaturized multi-channel optical communication platforms, materials and biomolecules sensing in attomolar concentrations, and the pharmaceutical industry.