Thermal radiation from finite photonic crystals
The ability of micro and nanostructured photonic materials to facilitate significant alteration of thermal radiation processes is receiving considerable attention due to both the scientific relevance and potential for technological applications.
In this area, we are exploring the possibility to control the thermal radiation through the use of microstructured photonic materials and to realize highly-efficient thermal-management and energy-conversion systems.
The formalism developed provides an extensive understanding of the origin of the modification of Planck’s radiation law in microstructured photonic reservoirs, and establish rigorous design principles for technological applications. We have demonstrated that thermal radiation characteristics are governed by the topology of the dispersion surface, and not the photonic density of states, as it was generally assumed and used to interpret or predict experimental results.
We have shown that through the presence of PBGs and the associated spectral and angular redistribution of photonic states, it is possible to have spectral regions over which thermal radiation is dramatically enhanced. Also, we have discovered that in a PBG material there exist “photonic caustics”, directions along which thermal radiation flux may become divergent, and thermal photon focusing effects appear. This ability to control the spectral and directional characteristics of thermal radiation in microstructured photonic systems greatly impacts applications.
Based on our theoretical studies, in collaboration with experimentalists, we have developed novel photonic crystal based spectral and angular-selective absorbers and highly efficient solar-cell and thermophotovoltaic components.