Mie and Bragg plasmons in subwavelength silver semi-shells

Area of Science:

• Plasmonics
• Optical Metamaterials
• Nanophotonics

Background:

• Two-dimensional arrays of silver semi-shells exhibit intricate reflection and transmission spectra.
• Understanding these spectral features is crucial for designing advanced optical devices.

Purpose of the Study:

• To deconstruct the complex spectral features of silver semi-shell arrays.
• To demonstrate the underlying physical mechanisms responsible for these spectral features.
• To show the possibility of exciting transverse dipolar plasmon resonances.

Main Methods:

• Analysis of reflection and transmission spectra of 100 and 200 nm silver semi-shell arrays.
• Theoretical deconstruction of spectral features.
• Investigation of light coupling into delocalized Bragg and localized Mie plasmons.

Main Results:

• Spectral features arise from the coupling of light into delocalized Bragg plasmons.
• Bragg plasmons induce localized Mie plasmons in the arrays.
• Transverse dipolar plasmon resonances are excited in semi-shells, despite unfavorable orientation.
• A strong and tunable spectral feature is observed in the mid-visible spectrum.

Conclusions:

• The observed spectral features are a result of coupled plasmonic phenomena.
• This work provides a pathway for controlling and tuning plasmon resonances in nanostructures.
• The findings have implications for the development of tunable optical components and sensors.