Tailoring of silicon nitride waveguide with ultra-flat and ultra-wide dispersion

A four-layered composite silicon nitride waveguide with an asymmetric horizontal slot is proposed. The waveguide exhibits an ultra-flat and low dispersion with four zero dispersion wavelengths over an ultra-wide bandwidth. In the wavelength range from 1269 nm to 2556 nm, the dispersion varies between -3.27 and 3.29 ps/nm/km. Dispersion tailoring is studied by tuning structural parameters of the composite waveguide. Nonlinear coefficient and phasematching condition in four-wave mixing process are explored, which confirm the proposed waveguide is promising in nonlinear applications.