Superluminal Pulse Reflection From Graphene Covered Lossless Dielectric Slab

Group delay of the optical pulse reflected from the graphene covered lossless dielectric slab is studied, and large negative group delay is demonstrated near a resonance of the slab due to the graphene sheet appearing on the surface of dielectric slab, even if the dielectric slab is lossless. It is shown that even a single-layer graphene (as thin as 0.34 nm) can allow for a greatly change of the optical pulse reflection property. It is important that the negative group delay can be actively tuned through electrical or chemical modification of the charge carrier density of the graphene. Numerical calculations further indicate that the group delay can be negatively reduced via addition of the number of the layers of graphene sheets and negatively enhanced at the surface plasmon polaritons frequency for different incident angles.