Fig. 5From: High-Efficiency Plasmonic Third-Harmonic Generation with Graphene on a Silicon Diffractive Grating in Mid-infrared RegionGeneration of FF and THF GPs on the GSSDG and the connected GSPWs. a The schematics of the GSSDG and the connected GSPWs on both sides when a normal-incidence x-polarized plane wave of FF illuminates the structure. The THF GPs are generated and guided along the two GSPWs after the FF GPs are excited in the GSSDG. The cross section of the GSPW is presented in the panel below, in which the graphene sheets and Si layer are denoted. b, c The |E| distributions of b FF and c THF GPs in the y-z plane as the grating section is illuminated by CW light with the power density of 0.19 MW/cm2 at 28.62 μm. d The CE of THG along the z direction. The black dashed lines in b–d represent the interfaces between the GSSDG and GSPWs. In b–d, Np is set at threeBack to article page