The ability to controllably localize temperature increases to specific locations within nanopatterned materials would open a new class of thermal metastructures capable of directing heat below the diffraction limit despite the adverse effects of thermal diffusion. While locally heating individual plasmonic nanoparticles within an assembly has been accomplished, exerting active control over the spatial distribution of temperature has remained elusive until now. In collaboration with the Willets group at Temple University and the Link group at Rice University, we demonstrate manipulation of the thermal near-field by resonant optical pumping of the in-phase and out-of-phase dipole plasmon modes of individual gold nanorod heterodimers. Guided by modeling and simulation, single-particle photothermal heterodyne imaging is used to observe the resulting asymmetric temperature distributions within and surrounding the nanorod heterodimers by collecting the light scattered from the optically heated system at each resonance. The photothermal images show wavelength-dependent temperature biasing across all heterodimers studied, demonstrating an unprecedented ability to actively manage the thermal near-field in a binary manner.

Active binary control of the thermal near field via plasmon hybridization

2019 Fall National Meeting

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