Fine tuning slow group velocity and small pulse broadening of surface plasmon polaritons along metal–nonlinear Kerr medium interface

We propose and demonstrate a new method to fine control the group velocity of slow surface plasmon polaritons (SPPs) propagating in a metal–nonlinear Kerr medium (MNKM) waveguide by changing the incident peak electric field intensity. Tunable group velocity results from nonlinear dispersion relationship of waveguide induced by Kerr effect. The validity of this method is confirmed by numerical simulations with the finite-difference time-domain (FDTD). When the pulse with center wavelength 400 nm and width 240 fs propagates in MNKM waveguide of length 6 μm, the largest pulse broadening is only 3.4% of the input pulse width. Our method offers a new avenue for potential applications of the tunable slow SPP pulse with small pulse broadening.