Theoretical investigation of electric field induces second harmonic generation in silicon nitride waveguide structures

Second-order nonlinearity can be demonstrated in popular CMOS materials such as silicon and silicon nitride by breaking the centrosymmetry of their crystalline structure. We present a detailed theoretical investigation of the electric field-induced second harmonic generation (EFISH) in silicon nitride waveguide. Up-and-down frequency-conversion operations are achieved through the periodic spatial distribution of metal electrodes around the waveguides, which induces an effective second-order nonlinearity and high-efficiency SHG. We use a computational model to numerically simulate the EFISH process inside the waveguide and calculate the charge carriers responsible for the electric field creation. The SHG efficiency is massively dependent on both the waveguide dimensions and the electric field creation. We obtain second-order electric susceptibility (χ(2)) up to 0.1735 pm/V with spectral bandwidth of around 4 nm.