Fig. 3: Exciton and anapole driven enhancement of WS2/MoS2 interface second harmonic generation.
a Raw counts of the SHG intensity as a function of the fundamental wavelength, for nanoantennas with radii of 280 nm, 290 nm and 300 nm (dot markers), and the reference sample (diamond markers). b Comparison between the SHG ratio for a nanoantenna with radius of 280 nm and the reflectance spectrum of the reference hetero-bilayer, where the SHG enhancement is resonant with the exciton position of the TMDC layers. c Three-dimensional plot of the SHG ratio, as a function of the nanoantenna radius and fundamental wavelength. d Normalized SHG signal for the same set of nanoantennas in panel (c), revealing a linear dependence of the maximum SHG emission and the anapole wavelength (dashed line). e Nonlinear parameter (βSH) as a function of the fundamental excitation wavelength, shown for hetero-bilayer nanoantennas (round markers) and reference heterostructure (diamond markers)
