Generalized coupled dipole method for thermal far-field radiation

TL;DR

This paper develops a comprehensive many-body theory within fluctuational electrodynamics to analyze thermal far-field radiation from nanoparticle assemblies near substrates, incorporating variable temperatures and complex geometries.

Contribution

It introduces a generalized coupled dipole method that accounts for multiple particles, substrates, and temperature variations in thermal radiation modeling.

Findings

Demonstrates the method with SiC and Ag nanoparticle assemblies.

Calculates thermal emission of a nanoparticle near a substrate using discrete dipole approximation.

Analyzes thermal radiation of a Si tip near a SiC substrate including near-field effects.

Abstract

We introduce a many body theory for thermal far-field emission of dipolar dielectric and metallic nanoparticles in the vicinity of a substrate within the framework of fluctuational electrodynamics. Our theoretical model includes the possibility to define the temperatures of each nanoparticle, the substrate temperature, and the temperature of the background thermal radiation, separately. To demonstrate the versatility of our method, we apply it in an exemplary way by discussing the thermal radiation of four particle assemblies of SiC and Ag nanoparticles above a planar SiC and Ag substrate. Furthermore, we use discrete dipole approximation to determine the thermal emission of a spherical nanoparticle in free space and close to a substrate. Finally, the calculation of the thermal far-field radiation of a sharp Si tip close to a SiC substrate using the discrete dipole approximation including the near-field scattering by the tip as well as the thermal emission of the tip and the contribution of the substrate which is partially blocked by the tip serves as another example.