  In this paper, we utilize coupled mode theory (CMT) to model the coupling
between surface plasmon-polaritons (SPPs) between multiple graphene sheets. By
using the Stimulated Raman Adiabatic Passage (STIRAP) Quantum Control
Technique, we propose a novel directional coupler based on SPPs evolution in
three layers of graphene sheets in some curved configuration. Our calculated
results show that the SPP can be transferred efficiently from the input
graphene sheet to the output graphene sheet, and the coupling is also robust
that it is not sensitive to the length of the device.
