Dispersion flattened single etch-step waveguide based on subwavelength grating

A novel subwavelength-grating-assisted (SWG-assisted) waveguide is proposed for dispersion flattening. Tuning the refractive index, which is a powerful tool in dispersion engineering, can be carried out through adjusting the properties of the SWG regions. It is particularly beneficial for controlling the flattened dispersion bandwidth. This will also eliminate the need for integration of other less compatible materials with silicon. Moreover, the SWG-assisted waveguide can be easily fabricated through a single etch-step process. By engineering the structural parameters of the waveguide, an ultra-flat dispersion profile with a total dispersion variation of 10 (ps/nm/km) over a wide bandwidth of 1615 nm is obtained. The possibility of bandwidth expansion, the fabrication friendly design, and the flattened dispersion profile of the proposed waveguide make it promising for wideband nonlinear applications.