Isotropic broadband absorption by a macroscopic self-organized plasmonic crystal

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Plasmonic properties are crucial for light-matter interactions.
• Controlling plasmon excitation over broad wavelength ranges is challenging.

Purpose of the Study:

• To investigate the plasmonic properties of a macroscopic gold-on-silica opal metallic grating.
• To demonstrate broad spectral and angular tunability of light-plasmon coupling.

Main Methods:

• Fabrication of a two-dimensional periodic metallic grating via gold deposition on a self-assembled silica opal.
• Structural characterization using microscopy.
• Optical reflection spectroscopy to analyze absorption spectra.
• Theoretical calculations to model surface-plasmon-polariton (SPP) coupling.

Main Results:

• Observed a transition from microscopic order to macroscopic isotropy in the grating structure.
• Measured a dip of near-complete absorption in optical reflection spectra.
• Attributed absorption to coupling with surface-plasmon-polaritons (SPPs).
• Demonstrated a broad continuum of coupled wavelengths at a specific incidence angle.

Conclusions:

• The developed metallic grating exhibits significant light-plasmon coupling over a wide range of visible wavelengths.
• The material's properties open new avenues for applications requiring broadband light-plasmon interactions.
• Tunable SPP coupling offers potential for advanced optical devices.