Optical response of supported gold nanodisks

Area of Science:

• Nanophotonics
• Optical properties of nanomaterials
• Plasmonics

Background:

• Ellipsometric spectra of planar arrays of gold nanodisks on glass substrates are analyzed.
• Previous models using uniaxial homogeneous layers with Lorentz-type dielectric functions showed deviations from experimental data.

Purpose of the Study:

• To accurately describe the ellipsometric spectra of gold nanodisk arrays.
• To investigate the optical response considering nanodisk shape and substrate interactions.

Main Methods:

• Modeling nanostructured arrays as uniaxial homogeneous layers with Lorentz-type dielectric functions.
• Utilizing a uniaxial effective medium dielectric function with nanodisks modeled as oblate spheroids.
• Considering dynamic depolarization factors and substrate interactions.

Main Results:

• The oblate spheroid model with dynamic depolarization factors and substrate interactions provides a qualitative and quantitative description of measured spectra.
• Deviations were observed when modeling nanodisks as simple uniaxial homogeneous layers.
• In-plane anisotropy and quadrupolar coupling effects contribute to a complex optical response.

Conclusions:

• The optical response of gold nanodisk arrays is complex and depends on factors beyond simple uniaxial models.
• Modeling nanodisks as oblate spheroids offers a more accurate description of their optical properties.
• Further investigation into anisotropy and coupling effects is warranted for a complete understanding.