Slow Surface Plasmons in Plasmonic Grating Waveguide

A metal/air/metal (MAM) plasmonic grating waveguide (PGW) consisting of two parallel silver slabs with periodic corrugations on their inner boundaries is developed to slow down the group velocity of surface plasmon polaritons (SPPs) excited at near-infrared frequencies. For a Gaussian pulse excitation with the full width at half maxim (FWHM) of 222 fs and the center wavelength of 1.58 μm, the group velocity of 0.034c and the group velocity dispersion (GVD) of 0.8 ps/mm/nm can be achieved in finite-difference time-domain (FDTD) simulations with pulse excitation. Furthermore, a chirped PGW with varying groove depth is also demonstrated as a way to trap light by adopting continuous excitation.