We theoretically describe and experimentally demonstrate a
graphene-integrated metasurface structure that enables electrically-tunable
directional control of thermal emission. This device consists of a dielectric
slab that acts as a Fabry-Perot (F-P) resonator supporting long-range
delocalized modes bounded on one side by an electrostatically tunable
metal-graphene metasurface. By varying the Fermi level of the graphene, the
accumulated phase of the F-P mode is shifted, which changes the direction of
absorption and emission at a fixed frequency. We directly measure the
frequency- and angle-dependent emissivity of the thermal emission from a
fabricated device heated to 250∘. Our results show that electrostatic
control allows the thermal emission at 6.61 μm to be continuously steered
over 16∘, with a peak emissivity maintained above 0.9. We analyze the
dynamic behavior of the thermal emission steerer theoretically using a Fano
interference model, and use the model to design optimized thermal steerer
structures.Comment: 8 pages, 4 figure