Slow Light in Waveguide Gratings on Silicon-on-Insulator Platform

Slow light phenomena have been of considerable interest in recent years because of the fundamental interest in controlling light propagation and for boosting advanced functionalities in optical devices, especially in integrated circuits on a silicon platform. In this work, we present a systematic analysis of slow light properties arising at the band edge in integrated silicon grating waveguides. By employing a combination of numerical methods and perturbation theory, we are able to explore a wide space of parameters with a reasonable computational effort. We show that the slow light bandwidth has a critical dependence on the geometrical structure parameters and that it can be improved by reducing the width of the thinner section in the grating. The best performance is obtained in the limit of the thinner section going to zero (i.e., for the lattice of trenches). An optimal compromise is found by considering the requirement that the structure can be connected to a standard silicon waveguide by an adiabatic taper. We also show that the slow light-light bandwidth can be further increased by reducing the thickness of silicon in the cladding region.