Extreme near field heat transfer modulation with graphene plasmon resonators

We present a near-field radiative thermal switch based on thermally excited surface plasmons in graphene resonators. The high tunability of graphene enables substantial modulation of near-field radiative heat transfer. When combined with the use of resonant structures, near field heat transfer overcomes the intrinsically broadband nature of thermal radiation. In canonical geometries, we use nonlinear optimization to show that stacked graphene sheets offer improved heat conductance contrast between “ON” and “OFF” switching states, but that a >10x higher modulation is achieved between isolated graphene resonators than for parallel graphene sheets. In all cases, we find that carrier mobility is a crucial parameter for radiative thermal switching. Furthermore, we discuss shape-agnostic analytical approximations for the resonant heat transfer that provide general scaling laws and allow for direct comparison between different resonator geometries dominated by a single mode. Our scheme is relevant for active thermal management and energy harvesting as well as probing excited state dynamics.