Third harmonic generation with the effect of nonlinear loss

We demonstrate an efficient third harmonic generation (THG) with the effect of nonlinear loss based on a proposed double-hybrid plasmonic slot waveguide structure. Silicon nanocrystal is integrated into the two parallel slots acting as the main interactive nonlinear material. To achieve phase matching condition, we analyze the relation between the guided mode dispersions and the waveguide geometrical parameters. The effect of nonlinear loss, which is contributed by the two-photon-absorption (TPA) effect, on the THG conversion efficiency is investigated numerically. The simulation results reveal that the THG conversion efficiency can be significantly enhanced by the field confinement and enhancement, whereas it is greatly impeded in the presence of the TPA effect (a decrement of 17.6% on the THG conversion efficiency with a pump power of 4 W). According to our calculation, the THG conversion efficiency of 0.91% without the consideration of the TPA effect and 0.75% with the TPA effect under a 4-W input pump power condition is achieved.