Validity of the effective medium theory for modeling near-field thermal emission by nanowire arrays

Nanowire arrays are promising man-made materials for tuning the spectrum and magnitude of near-field thermal radiation. Near-field radiative properties nanowire often studied using effective medium theory (EMT). In this paper, we inspect validity Maxwell-Garnett (MG) Bruggeman (BR) EMTs predicting emission by quartz indium tin oxide (ITO) arrays. The energy density predicted is compared with numerical simulations obtained discrete dipole approximation. For arrays, which support localized surface phonons in infrared region, neither MG nor BR EMT can accurately predict even at distances, zo, greater than array pitch, L over π. Based on performed simulations, agrees best T-DDA when 1<Lzo<π. It also shown that slightly more consistent EMT. ITO array, does not plasmons provides an acceptable estimations Finally, it observed vary a factor two lateral directions cannot be captured