Azadeh Didari

Near- to far-field coherent thermal emission by surfaces coated by nanoparticles and the evaluation of effective medium theory

Near-field thermal radiation may play significant role in the enhancement of energy harvesting and radiative cooling by new types of designer materials, which in turn can be crucial in the development of future devices. In this work, we present a case study to explore near- to far-field thermal emission and radiative flux from a thin polar SiC film coated by different size and shape nanoparticles. The same geometry with nano-particles is also considered as a layered medium, which is analyzed using Effective Medium Theory (EMT). A significant enhancement of emission, particularly at the far infrared, is observed when nanoparticles are placed on the surface of a SiC film with certain periodicities, which shows potential use of these structures for radiative cooling applications. Yet, these enhancements are not observed when the EMT approach is adapted, which is questioned for its accuracy of predicting near-to-far field transition regime of radiation transfer from corrugated surfaces.

Near-field thermal radiation transfer by mesoporous metamaterials.

In this work, we investigate the impact of nano-scale pores within structured metamaterials on spectral near-field radiative transfer. We use Finite Difference Time Domain Method (FDTD) and consider uniform and corrugated SiC substrates filled with rectangular nano-scale vacuum inclusions having equivalent diameters of 10, 37 and 57 nm. We report the appearance of the secondary and tertiary resonance peaks at different frequencies as a function of changing pore diameter, which cannot be predicted if an effective medium theory approximation is used.

Biomimicry designs for passive optical solutions for nanoscale radiative cooling applications

Inspired by the mechanism of the wings of Morpho butterfly, here we propose biomimicry designs which have the potential to be used for radiative cooling purposes. We numerically analyzed the spontaneous emission at near-field and determined radiative heat flux at nano-scale in order to investigate the impact of geometric variations and material selection in these systems. Our findings suggest that these metasurfaces which support phononic surface waves, can be used to tailor radiative heat transfer at nano-scale in the atmospheric transparency window (8-13 μm) within the infrared regime.

Far-field thermal emission by metamaterials with nano-scale porosities and corrugations

The far-field thermal radiative transfer from porous SiC substrates filled with vacuum inclusions is explored using the FDTD approach within the spectral range of 400 nm to 20 µm wavelengths.