Tunable Group Delay of the Optical Pulse Reflection From Fabry–Perot Cavity With the Insertion of Graphene Sheets

We have theoretically investigated the group delay of the TE-polarized beam reflected from a Fabry-Perot cavity with the insertion of the graphene sheets in the near-infrared band. It is shown that even a single-layer graphene allows for notable variation of group delay. Group delay can be enlarged negatively and can be switched from positive to negative, or vice versa. Importantly, the group delay depends on the Fermi energy of the graphene sheets, and thus, it can be actively controlled through electrical or chemical modification of the charge carrier density of the graphene. Furthermore, the influences of the position of graphene in the Fabry-Perot cavity, the mirror transmittance, and the number of graphene layers on group delay are clarified.