Electrostatic Steering of Thermal Emission with Active Metasurface Control of Delocalized Modes

TL;DR

This paper presents a graphene-integrated metasurface that enables electrically tunable directional control of thermal emission, demonstrating continuous steering over 16 degrees with high emissivity, combining experimental and theoretical analysis.

Contribution

It introduces a novel actively tunable thermal emission device using a graphene metasurface integrated with a Fabry-Perot resonator, with experimental validation and theoretical modeling.

Findings

Thermal emission can be steered over 16 degrees at 6.61 μm wavelength.

Peak emissivity remains above 0.9 during steering.

Theoretical Fano interference model accurately describes the dynamic behavior.

Abstract

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$^{\circ}$. Our results show that electrostatic control allows the thermal emission at 6.61 $\mu$m to be continuously steered over 16$^{\circ}$, 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.