Optimized Colossal Near‐Field Thermal Radiation Enabled by Manipulating Coupled Plasmon Polariton Geometry

Collective optoelectronic phenomena such as plasmons and phonon polaritons can drive processes in many branches of nanoscale science. Classical physics predicts that a perfect thermal emitter operates at the black body limit. Numerous experiments have shown that surface phonon polaritons allow emission two orders of magnitude above the limit at a gap distance of ≈50 nm. This work shows that a supported multilayer graphene structure improves the state of the art by around one order of magnitude with a ≈1129‐fold‐enhancement at a gap distance of ≈55 nm. Coupled surface plasmon polaritons at mid‐ and far‐infrared frequencies allow for near‐unity photon tunneling across a broad swath of k‐space enabling the improved result. Electric tuning of the Fermi‐level allows for the detailed characterization and optimization of the colossal nanoscale heat transfer. Coupled plasmon polaritons excited by gap‐bridging multilayer graphene/SU8 heterostructures lead to near‐perfect photon‐tunneling probability and improve the state of the art by one order of magnitude in near‐field thermal radiation (NFTR). Electric tuning of the graphene Fermi‐level allows for optimized NFTR enhancement. Colossal energy transfer should inspire potential applications in thermophotovoltaic and so on.