Fig. 5
From: Giant two-photon upconversion from 2D exciton in doubly-resonant plasmonic nanocavity
Enhanced PL and SHG in nanocavity by single resonance effect. a PL maps of the plasmonic nanocavity effect on exciton emission excited by the photon energy of 2.33 eV. b (downconversion PL), c(SHG) Excitation power-dependent integrated upconverted emission intensity (down) and enhancement (top) for monolayer WS2 in the designed plasmonic cavity. The experimental results can be fitted well by the blue and red dotted lines based on the power law formula I = bPα. The EMCCD image of the laser spot and the SEM image of the Au nanoparticle are shown as insets. d Schematic of downconversion, two-photon excited fluorescence and SHG processes, where UC and DC correspond to the upconversion and downconversion processes
