Truncated Airy pulses supercontinuum generation in a silicon-on-insulator optical waveguide including third-harmonic generation and negative-frequency Kerr terms

Abstract

We report in this work the numerical study of the supercontinuum generation (SCG) phenomenon raised from femtosecond truncated Airy pulses within a silicon-on-insulator (SOI) waveguide including loss effects, third-harmonic generation (THG) and negative-frequency Kerr (NFK) terms. This study is conducted through a modeling based on the full unidirectional pulse propagation equation (UPPE) model which allows to assume the existence of the NFK term in the Kerr nonlinearity with a spectral filtering. The various effects of the linear loss (LL), the free-carrier absorption (FCA)/ free-carrier dispersion (FCD), the two-photon absorption (TPA), the THG, the NFK, the peak power, the pulse duration and the pulse shape are explored and discussed. For the shape comparison, we use a symmetrical profile of the sech-type pulse. More specifically, we show that the Airy pulse has SCG spectra that are less influenced by the waveguide than the sech-type symmetric pulse; moreover, the losses effectively reduce the spectral intensity (S.I) and the spectral bandwidth (S.B) of the spectra while the THG and the NFK increase them. However, the most deleterious factor for the Airy pulse is the LL, while that of the sech-type pulse is the TPA. The SCG spectra of the Airy pulse are broader and more coherent than that of the sech-type in the studied waveguide. Due to the presence of linear and nonlinear loss terms, the increase in signal energy is deleterious to the SCG in this silicon waveguide; this results in smaller spectra as peak power and pulse duration increase.