Fig. 1
From: Giant two-photon upconversion from 2D exciton in doubly-resonant plasmonic nanocavity
Design and characterization of plasmonic upconversion devices. a Schematic of the designed AuNCs/WS2/substrate plasmonic upconverter devices. b Desired band alignment diagram of monolayer WS2 in plasmonic nanocavities and the photon upconversion process of 2D excitons. c Bright- and d dark-field microscope optical images of a representative sample. e Scanning electron micrograph of 170 nm AuNCs on the substrate, and the inset shows a magnified image from the top view. f Excitation laser and monolayer WS2 PL spectra overlapping the simulated scattering spectrum of a plasmonic nanocavity, which is consistent with experimental results. The excitation laser and upconverted emission spectra are doubly resonant with plasmonic cavity modes at 1.55 and 2.0 eV, respectively. All the spectra are normalized
