Substrate-enhanced photothermal nano-imaging of surface polaritons in monolayer graphene

REVIEWS AND HIGHLIGHTS	QUANTUM SCIENCE	MOLECULAR AND SOFT-MATTER	ULTRAFAST NANO-OPTICS AND NANOPHOTONICS	MINERALOGY AND GEOCHEMISTRY

Fabian Menges, Honghua U. Yang, Samuel Berweger, Anirban Roy, Tao Jiang, and Markus B. Raschke
APL Photonics 6, 041301 (2021).
DOI PDF

Surface polaritons comprise a wealth of light–matter interactions with deep sub-wavelength scale confinement of electromagnetic modes. However, their nanoscale localized dissipation and thermalization processes are not readily accessible experimentally. Here, we introduce photothermal force microscopy to image surface plasmon polaritons (SPPs) in monolayer graphene through their non-radiative SiO₂ substrate dissipation. We demonstrate the real-space SPP imaging via photo-induced atomic force detection, and from comparison with scattering-type scanning near-field optical microscopy imaging attribute the force response to substrate dissipation-enhanced thermal expansion. This work illustrates that nano-optical tip–sample induced dissipative forces facilitate a direct mechanical detection of surface polariton interactions with monolayer sensitivity.