Engineering a strong and stable ultraviolet chiroptical effect in a large-area chiral plasmonic shell

Area of Science:

• Plasmonics
• Metamaterials
• Chiroptics

Background:

• Ultraviolet chiral metamaterials (UCM) are crucial for manipulating high-energy photons and molecular interactions.
• Fabricating UCM is challenging due to small feature sizes and complex geometries, limiting their development.

Purpose of the Study:

• To design and fabricate novel ultraviolet chiral plasmonic shells (UCPS).
• To overcome fabrication challenges and achieve strong ultraviolet chiroptical resonances.
• To investigate the stability and tunability of the fabricated UCPS.

Main Methods:

• Stepwise aluminum deposition combined with colloid-sphere assembly.
• Optimization of deposition parameters to overcome cancellation effects.
• Protection and passivation techniques (N2, UV-ozone) for enhanced stability.

Main Results:

• Demonstrated a strong circular dichroism (CD) signal (>1 deg) in the UV region via simulation and experiment.
• Identified key resonance modes: surface chiral lattice, whispering gallery, and inter-shell interactions.
• Showcased tunability of chiroptical resonances by altering structural parameters and deposition temperature.

Conclusions:

• Successfully fabricated stable and tunable UCPS with strong UV chiroptical responses.
• The developed UCPS offer a promising platform for advanced optical applications in the ultraviolet spectrum.
• Systematic investigation of geometrical models, electromagnetic modes, and tunable resonances provides a foundation for future designs.