# Near-Field Thermal Emission by Periodic Arrays

## TL;DR

This paper introduces an efficient periodic method for modeling near-field thermal emission from two-dimensional arrays of sub-wavelength emitters, enabling analysis of complex shapes and inhomogeneous materials with reduced computational effort.

## Contribution

A novel periodic Green's function-based modeling technique for near-field thermal emission that simplifies computations by discretizing only one array period.

## Key findings

- Method accurately matches non-periodic DDA simulations.
- Efficiently models complex and inhomogeneous emitter arrays.
- Versatile tool for designing near-field thermal emitters.

## Abstract

Near-field thermal emission can be engineered by using periodic arrays of sub-wavelength emitters. The array thermal emission is dependent on the shape, size, and materials properties of the individual elements as well as the period of the array. Designing periodic arrays with desired properties requires models that relate the array geometry and material properties to its near-field thermal emission. In this study, a periodic method is presented for modeling two-dimensional periodic arrays of sub-wavelength emitters. This technique only requires discretizing one period of the array, and thus is computationally beneficial. In this method, the energy density emitted by the array is expressed in terms of array's Green's functions. The array Green's functions are found using the discrete dipole approximation in a periodic manner by expressing a single point source as a series of periodic arrays of phase-shifted point sources. The presented method can be employed for modeling periodic arrays made of inhomogeneous and complex-shape emitters with non-uniform temperature distribution. The proposed technique is verified against the non-periodic thermal discrete-dipole-approximation simulations, and it is demonstrated that this method can serve as a versatile and reliable tool for studying near-field thermal emission by periodic arrays.

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Source: https://tomesphere.com/paper/1812.02520