Dual-Mode GVD Tailoring in a Convex Waveguide

Mode division multiplexing (MDM) silicon photonic integrated circuits (PICs) have been widely developed for achieving high-speed optical interconnects and communications. As an excellent nonlinear optical platform, silicon PICs also receive great attention in applications of optical parametric devices and nonlinear optical signal processing. However, it is still challenging to develop MDM optical parametric devices due to the strong mode dependence of the group velocity dispersion (GVD) in a silicon waveguide. Here, we theoretically design a convex waveguide exhibiting almost the same GVD profiles for quasi-TE
₀
and quasi-TE
₁
modes based on the standard fabrication flow of silicon photonic foundries. Specifically, flat GVD curves varying from -1500 ps/nm/km to -1000 ps/nm/km are obtained for the two modes in a convex waveguide within a spectral region of 1.37 μm to 1.75 μm covering from E-band to U-band. The study is expected to open an avenue for exploring unprecedented MDM nonlinear applications.