Heat Generation in Spatially Confined Solids Through Electronic Light Scattering

Abstract

In this Letter, we study the optical heating of spatially dispersive solids due to electronic light scattering (ELS), a phenomenon driven by indirect optical transitions. In this process, a spatial heterogeneity generates an optical near-field photon with expanded momentum, leading to electron-photon momentum matching, followed by thermalization of the electron system promoting optical heating. We experimentally demonstrate this effect by melting spatially confined semiconductor (Si) and metal (Au) under continuous-wave laser pump within the transparency window. ELS is a dominant physical process in media with strong spatial dispersion, underlying a variety of thermo-optical applications.