Tailoring chiro-optical effects by helical nanowire arrangement

Area of Science:

• Plasmonics
• Nanophotonics
• Chiroptical Spectroscopy

Background:

• Chiroptical properties of 3D metallic helical systems are crucial for nanoscale chiral device applications.
• Existing single-helical nanostructures exhibit limitations in enhancing chiro-optical effects, particularly concerning wavelength dependence and polarization purity.

Purpose of the Study:

• To experimentally investigate and compare the chiro-optical properties of single and triple-nanowire metallic helical systems at optical frequencies.
• To explore the impact of geometrical configuration and inter-helix coupling on chiro-optical performance.

Main Methods:

• Fabrication and characterization of single and triple-nanowire metallic helical structures.
• Experimental measurement of chiro-optical properties, including optical activity, g-factor, and extinction ratio, across a broad spectral range.
• Analysis of the influence of helical configuration and symmetric spatial arrangement on light-matter interactions.

Main Results:

• Single-helical nanostructures show limited enhancement of chiro-optical effects and polarization purity.
• Triple-helical nanowires exhibit enhanced chiro-optical properties due to coupling between intertwined coaxial helices.
• Triple-helical configurations achieve a broad spectral range (500 nm in visible), large optical activity (up to 8°), and improved g-factor and extinction ratio, independent of sample orientation.

Conclusions:

• Configurational internal interactions in metallic nanostructures strongly correlate with chiral feature designation.
• Triple-helical nanowire systems offer a promising platform for advanced nanoscale chiral device engineering with tunable and robust chiro-optical responses.