Precise Control of Group Velocity by Pulsewidth in a Plasmonic Superlattice

We propose and demonstrate a new method to control precisely the group velocity of slow surface plasmon polaritons propagating in a superlattice by changing incident pulsewidth. The validity of this method is confirmed by numerical simulations with the finite-difference time-domain. The group velocities for different frequency components are different. Therefore, for the Gaussian pulse, the group velocity is varied with the pulsewidth. Our method of control group velocity offers a new avenue for potential applications of the tunable slow surface plasmon polaritons.