Wavelength conversion in the presence of Raman amplification in silicon rib waveguides.

Abstract

This study presents the wavelength conversion facilitated by the interplay between a co-propagating triangular signal and a Gaussian pump by analyzing the nonlinear phase shift in highly nonlinear silicon-core rib waveguides, marking the first report of its kind, to our knowledge. The interaction between the pump and the signal enables possible amplification driven by cross-phase modulation and stimulated Raman scattering. To substantiate these findings, four waveguides are designed and optimized. Numerical solutions of the coupled amplitude equations result in a Raman gain of ∼18-22dB within a compact size, achieving performance comparable to or exceeding previously reported results. As predicted by the analytical model, spectral intensity doublets emerge, with their wavelength shifts and peak power ratios showing strong dependence on pump power and signal pulse width. Higher pump power causes larger wavelength shifts, while broader signal pulses expedite spectral splitting. The observed red-shift ranges from 65 to 81 nm, while the blue-shift spans 54 to 64 nm. Additionally, TPA and FCA play a crucial role in shaping the spectral doublet, particularly in highly nonlinear silicon waveguides. This work represents the first systematic exploration of wavelength conversion through pump-signal interaction in silicon rib waveguides, incorporating carrier lifetime effects and offering valuable insights into controlling spectral doublet generation for integrated photonic applications.