Sidelobe-Suppressed Silicon Waveguide Gratings Through Asymmetrically-Apodized Corrugations

We report detailed investigations on the impact of corrugation width design on the resulting sidelobe suppression from a Gaussian-apodized silicon waveguide gratings (SWGs). To address the nonlinear relationship between the waveguide width and effective index, corrugation widths at inner and outer sidewalls of SWGs should be individually optimized to warrant a constant waveguide effective index mean along the light propagation, thus enables balanced Gaussian apodization for sidelobe suppression at both edges of optical stopband. We also confirm that sidelobe-suppressed responses are reproducible from die-to-die and wafer-to-wafer despite of its rounded grating profile. We have demonstrated the use of such apodized SWGs in constructing an add-drop multiplexer.