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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.

We investigate the chiro-optical properties of the electromagnetic near-field associated with the excitation of collective optical resonances (surface lattice resonances) in achiral plasmonic lattices. These arrays are specially designed to support dispersive resonances with nontrivial, multipolar near-field distributions in the surroundings of the nanostructure, which gives rise to an enhanced chiro-optical response. The presence of these multipolar resonances in lattices without explicitly broken mirror symmetry is experimentally confirmed by far-field extinction measurements, while the angular, spectral, and spatial dependence of the associated chiral near-field are numerically simulated. In contrast with typical pseudochiral systems, the extended chiro-optical near-field response appears even at normal incidence. We believe that surface lattice resonances in achiral plasmonic lattices can be potentially utilized as a substrate for enhanced background-free enantioselectivity and tunable chiral molecule recognition over large areas.

We experimentally demonstrate a broadband enhancement of the light absorption in graphene over the whole visible spectrum. This enhanced absorption is obtained in a multilayer structure by using an Attenuated Total Reflectance (ATR) configuration and it is explained in terms of coherent absorption arising from interference and dissipation. The interference mechanism leading to the phenomenon of coherent absorption allows for its precise control by varying the refractive index and/or thickness of the medium surrounding the graphene.