Design of infrared optical absorber using silver nanorings array made by a top-down process.

Area of Science:

• Plasmonics
• Metamaterials
• Nanophotonics

Background:

• Metasurfaces offer unique control over light-matter interactions.
• Optically-induced magnetic responses are crucial for advanced optical devices.
• Controlling absorption in the near-infrared spectrum is vital for various applications.

Purpose of the Study:

• To numerically simulate and experimentally fabricate a metasurface composed of silver nanorings.
• To optimize nanostructure parameters for enhanced absorption at optical frequencies.
• To investigate the impact of structural parameters on optical responses.

Main Methods:

• Parametric study using Finite Difference Time Domain (FDTD) simulations.
• Numerical calculation of absorption and scattering cross sections.
• Fabrication via e-beam lithography and metallization, followed by optical characterization.

Main Results:

• Full control over resonance peaks and absorption enhancement in the near-infrared (NIR) spectral range.
• Demonstrated optimization of absorption coefficient by tuning nanoring dimensions and periodicity.
• Experimental results show good agreement with numerical simulations.

Conclusions:

• Successful realization of a silver nanoring metasurface with tunable absorption properties.
• The study highlights a top-down fabrication process for NIR metasurfaces.
• This work provides a pathway for designing advanced optical devices with tailored absorption characteristics.