Nanophotonic engineering of far-field thermal emitters

Abstract

Thermal emission is a ubiquitous and fundamental process by which all objects at non-zero temperatures radiate electromagnetic energy. This process is often assumed to be incoherent in both space and time, resulting in broadband, omnidirectional light emission toward the far field, with a spectral density related to the emitter temperature by Planck’s law. Over the past two decades, there has been considerable progress in engineering the spectrum, directionality, polarization and temporal response of thermally emitted light using nanostructured materials. This Review summarizes the basic physics of thermal emission, lays out various nanophotonic approaches to engineer thermal emission in the far field, and highlights several applications, including energy harvesting, lighting and radiative cooling.

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Fig. 1: Physics of thermal emission.
Fig. 2: Narrowband and directive thermal emission from nanophotonic systems.
Fig. 3: Dynamic modulation of thermal emission.
Fig. 4: TE control for energy conversion and lighting.
Fig. 5: Radiative cooling.

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Acknowledgements

M.A.K. acknowledges financial support from the NSF (ECCS-1750341) and ONR (N00014-16-1-2556). A.K. and A.A. acknowledge support from the AFOSR (MURI grant no. FA9550-17-1-0002), the Department of Defense, the Simons Foundation and the National Science Foundation. D.G.B. acknowledges support from the Knut and Alice Wallenberg Foundation. We acknowledge S. Noda for sending data for our figures, and A. Lenert for helpful discussions.

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Correspondence to Mikhail A. Kats.

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