Slow-light effect via Rayleigh anomaly in high contrast gratings

We investigate slow light effect of subwavelength gratings via Rayleigh Anomaly on both infinite and finite size high index contrast gratings. Our results show that the local group velocity of the transmitted light can be significantly reduced due to the optical vortex, which can inspire a new mechanism to enhance light-matter interactions for optical sensing and photo detection. However, the slow light effect will diminish as the transmitted light propagates further away from the grating surface, and the slow-down factor decreases as the grating size shrinks.