Light-to-heat dissipation in nanoscale structures: from ultrafast optical modulation to steam generation

Abstract

Nanostructures store energy differently upon interaction with radiation, depending on the considered time scale, system size, and interacting components. Properly designed nanostructured surfaces confine electromagnetic energy, making it available as high energy electrons and confined fields, far-field scattering, heat or thermal radiation. This talk will show how the spatially inhomogeneous electromagnetic absorption in metallic nanostructures leads to a space-dependent out-of-equilibrium hot carrier population, whose < 1 ps thermalization can be exploited for ultrafast all-optical polarization modulation. Eventually, heat is generated through a slower electron-phonon scattering process. I will show how ultrathin (~250nm) plasmonic metasurfaces can absorb ~90% of the solar spectrum, leading to ~GW/m3 of dissipated power exploited, for example, for steam generation, relevant for sterilization or water desalination applications.