Unraveling Coherence Effects of Coupled Resonant Thermal Emitters

In this talk, we will discuss the interactions between resonant thermal emitters to realize complex coherence effects, such as thermal focusing. We will particularly examine three key regimes: response governed by local resonances, nearest-neighbor coupling, and collective modes. Using germanium nanorods on a gold backplane, we experimentally measure local resonances of individual germanium rods (600 nm tall) with varying widths that tune the peak resonances from 4 to 10 mm. With these resonant emitters, we construct finite-sized arrays that supports collective modes spanning the spectral range between the dipole and quadrupole resonances of the constituent resonators. Finally, we introduce defects into the arrays, which emit and scatter radiation at wavelengths within and beyond the local resonances of the constituent resonators of the finite array.<br/>We will present simulations and (time-permitting) provide an analytical explanation of the contributions of each of these effects, with a focus on nearest-neighbor interactions versus collective modes for applications in thermal lensing.