The chiroptical response of aluminum nano-crescents at ultraviolet wavelengths

• Published in: Nano letters Vol. 20; no. 5; pp. 3656 - 3662
• Main Authors: Davis, Matthew S., Zhu, Wenqi, Strait, Jared, Lee, Jay K., Lezec, Henri J., Blair, Steve, Agrawal, Amit
• Format: Journal Article
• Language: English
• Published: 27.04.2020
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.0c00586

Manipulation of plasmon modes at ultraviolet wavelengths using engineered nanophotonic devices allows for the development of high-sensitivity chiroptical spectroscopy systems. We present here an experimental framework based on aluminum-based crescent shaped nanostructures that exhibit a strong chiroptical response at ultraviolet wavelengths. Through utilization of higher-order plasmon modes in wavelength-scale nanostructures, we address the inherent fabrication challenges in scaling the response to higher frequencies. Additionally, the distinct far-field spectral response types are analyzed within a coupled-oscillator model framework. We find two competing chiroptical response types that contribute towards potential ambiguity in the interpretation of the circular dichroism spectra. The first, optical activity, originates from the interaction between hybridized eigenmodes while the second manifests as a response superficially similar to optical activity but originating instead from differential near-field absorption modes. The study of the chiroptical response from nanoplasmonic devices presented here is expected to aid the development of next-generation chiroptical spectroscopy systems.