Temporal grating of semiconductor nanoantennas for high-density solar energy harvesting

Abstract Achieving ultra-compact, high-efficiency solar harvesting remains a central challenge in nanophotonics. Here, we demonstrate an active semiconductor nanoantenna design that dramatically enhances solar energy density through synchronized temporal modulation of its optical susceptibility. Unlike conventional passive nanoantennas, our approach uses an intensity-modulated pump laser to dynamically vary the free-electron density, creating a ‘plasmonic chirp’ that matches the round-trip travel time of incident photons within the nanoantenna. This time-synchronized gating leads to a form of temporal trapping, which substantially increases photon confinement and absorption. Experimentally verified numerical simulations predict solar energy densities exceeding 10 GJ m −3 —over an order of magnitude higher than standard passive designs. In addition to a comprehensive but compact numerical model, we also propose an expanded experimental platform to realize the core mechanism at scale. This work introduces a novel method for high-density solar energy harvesting at the nanoscale, with potential to significantly advance next-generation photovoltaics and optoelectronic devices.