New frontiers of thermal photonics

All objects that we encounter in our everyday life emit thermal radiation. In our quest to better understand and utilize thermal radiation, last few decades have witnessed significant advances using micro- and nano-photonic design with advanced computational and experimental techniques and interdisciplinary approaches. Thus, the field of thermal photonics has emerged with many commercialized applications such as photovoltaic technology, radiative cooling, infrared cameras, imaging and metrology etcetera.
In this talk, I will discuss new ventures which lie within our reach based on three emerging research directions. First, I will reveal a new 'nonequilibrium'-based mechanism for generating spin-polarized or circularly polarized light using coupled antennas of Reststrahlen materials such as silicon carbide, held at unequal temperatures. Second, I will discuss an interesting possibility of using 'nonreciprocal' materials such as semiconductors or metals in magnetic field, ferromagnets or magneto-electric materials, to observe counter-intuitive nonzero radiative heat current without any temperature difference. And third, I will show how 'nonlinear' interactions between thermal photons facilitated by χ (2) or χ (3) nonlinear media such as quantum wells or chalcogenide glasses and enhanced by resonant structures, can be utilized to surpass the fundamental blackbody limit on thermal emission as well as to realize solid-state thermal refrigeration which can cool things down to cryogenic temperatures below 100K. Our work offers new fundamental and applied avenues at the forefront of thermal photonics.