Giant enhancement of phonon–electron coupling in graphene under femtosecond laser heating at room temperature

Abstract In recent years, phonon-electron carrier dragging has emerged as an innovative approach for modulating energy transfer in low-dimensional systems. In this Letter, we explore the fundamental mechanisms of electron-phonon coupling and the role of thermal lag behavior in ultrafast heat transport. We present a theoretical investigation of non-equilibrium thermal dynamics in graphene under femtosecond laser excitation, emphasizing the role of phonon-branch-resolved electron–phonon coupling. This framework provides new insight into ultrafast energy transfer processes at femtosecond timescales and illustrates key deviations from the predictions of the classical two-temperature model (TTM), particularly in spatially localized heat transport. Our results show that a 190 fs laser pulse induces a strong non-equilibrium state, followed by momentum redistribution among the excited carriers. This is then followed by effective cooling of the carrier distribution on a 450 fs timescale through phonon emission.