Modulation Instability in Silicon Optical Waveguide Considering Linear Loss and Two-Photonic Absorption

Conditions and gain spectra of modulation instability (MI) induced by combined effects of self-phase modulation and waveguide dispersions are investigated, taking into account the linear loss and two-photonic absorption (TPA) of silicon-on-insulator (SOI) waveguide simultaneously. Formulation for calculating the gain of MI is deduced theoretically. Impacts of various parameters to gain spectra of MI are analyzed theoretically and simulated in detail. Both theoretical analysis and simulation show that strong MI takes place even in the existence of low light power. Linear loss of waveguide obviously impacts gain spectra even within short propagation distance. The peak gain frequency and bandwidth of gain spectra decrease to 42.68% and 41.38% of their maximum, respectively, at propagation distance 5mm, because of linear loss.