Enhanced THz third-harmonic generation in graphene via hot-carrier effects in a hybrid topological plasmonic cavity
Phys. Rev. Applied 25, 024024 – Published 6 February, 2026
DOI: https://doi.org/10.1103/xw8y-q3w2
Abstract
Graphene is a promising material for nonlinear THz applications due to its high third-order susceptibility and tunable optical properties. Its strong nonlinear response, driven by free-carrier thermodynamics, facilitates efficient third-harmonic generation (THG), which can be further enhanced using resonant metasurfaces and plasmonic structures. In this study, we use a platform designed to boost THG at THz frequencies by integrating graphene ribbons into the interface between topological photonic crystals. To accurately capture the temperature dependence of the nonlinear optical response, we perform coupled simulations to model graphene’s optical and thermodynamic responses under THz photoexcitation, incorporating photoinduced hot-carrier effects within a multiphysics computational framework. This approach unveils the influence of carrier heating on THG, providing a more accurate description of nonlinear THz processes and revealing previously overlooked mechanisms of third-order conductivity modulation. We show that the elevated carrier temperature promotes high conversion efficiencies at moderate input intensities, within a design that operates in both reflection and transmission modes for advanced ultrafast optoelectronic devices in the THz regime.
