Tunable plasmon-induced transparency and slow light in a metamaterial with graphene

We proposed a metal grating-coupled graphene metamaterial in mid-IR frequency. An obvious plasmon-induced transparency (PIT) effect that can be tuned by Fermi energy of graphene has been achieved due to the coupling between two graphene surface plasmons. The physical origins of the tunable PIT effect are analyzed, and the influences of grating period and groove on the PIT effect are discussed. It is found that the amplitude and the width of the transparency window of PIT can be effectively modulated by grating period and groove respectively. Finally, the results are applied to the slow light, and a maximum group delay 0.4 ps can be achieved. We believe the designed structure may have a good application in slow light devices.