Enhancement of Light Absorption by Leaky Modes in a Random Plasmonic Metasurface

In this work, we study experimentally and theoretically the enhanced light absorption on a supported random plasmonic monolayer made of gold nanospheres in a total internal reflection configuration. The underlying physics can be understood in terms of leaky lossy guided modes excited in the monolayer, arising due to a balanced interplay of the nanoparticles’ near-field coupling and scattering. The experimental results are supported by analytical calculations carried out with two different models: an effective medium model, known as the dipolar model, and the so-called coherent scattering model, which is an approximate solution to a set of multiple-scattering equations. The metasurfaces we propose in this work might represent significant application opportunities in many technological areas, including refractive index and molecular sensing, plasmon-enhanced chemistry, surface-enhanced Raman spectroscopy (SERS), tunable mirrors, and light-harvesting devices.