Long-lived modulation of plasmonic absorption by remote thermal injection

Light interactions capable of inducing charge and energy transfer across interfaces are the fundamental basis for a multitude of technologies, including photocatalysis, energy harvesting, and photodetection. One of the more common mechanisms associated with these processes relies on injection of the charge carrier iteself. In this work, we elucidate upon a novel means of of electronic energy injection that can be accessed by relying on non-equilibrium dynamics achievable at metal-semiconductor interfaces that has yet to be realized. This remote thermal injection (RTI) process is demonstrated through an ultrafast pump-probe technique that relies on monitoring the optical properties of a mid-infrared epsilon-near-zero cavity following optical excitation of a remote contact, providing a highly sensitive probe into the spatial variations of electron density and energy relaxation mechanisms in the heterostructure. These results are further supported via ab initio density functional theory (DFT) simulations.