Fluctuational electrodynamics simulations (SCUFF-EM)

Jul 12, 2022

Fluctuational electrodynamics (FE) is a theoretical framework for computing thermal radiation and radiative heat transfer in systems where electromagnetic fluctuations play a central role. It is based on the fluctuation-dissipation theorem, which relates the spontaneous electromagnetic fluctuations of a material in thermal equilibrium to its dielectric response. In polar dielectric materials such as silicon carbide or silicon dioxide, these fluctuations can couple to optical phonons to form surface phonon-polaritons (SPhPs) — evanescent electromagnetic modes that propagate along surfaces and interfaces and can carry thermal energy over distances far exceeding what is possible via photon radiation alone.

SCUFF-EM is a free, open-source implementation of the fluctuating-surface-current (FSC) approach to fluctuational electrodynamics. The method discretizes material surfaces into a mesh of triangular elements and solves surface integral equations to compute the electromagnetic Green’s functions of the system. From these Green’s functions, SCUFF-EM can calculate near-field radiative heat transfer between bodies, far-field thermal emission spectra, and Casimir forces, for geometries of arbitrary shape that would be intractable with analytical methods. The boundary element formulation makes the method especially well suited to thin films, membranes, and nanostructured surfaces, where SPhPs are confined and strongly enhanced.

In our research, SCUFF-EM is used to simulate radiative heat transfer mediated by surface phonon-polaritons in dielectric thin films and multilayer systems, and to interpret the corresponding experimental measurements. This includes computing in-plane heat conduction via SPhP propagation along suspended membranes, as well as near-field and far-field heat exchange between closely spaced polar nanostructures. More details can be found in the Polaritonics project page.

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