Array periodical nanofocusing effect in nanoscale three-dimensional surface plasmon polariton waveguide arrays

Abstract

In this paper, the array periodical nanofocusing effect in a kind of nanoscale three-dimensional surface plasmon polariton (SPP) waveguide array is introduced. The refractive index of the dielectric layer in the three-dimensional SPP waveguide arrays has a parabolic distribution. The SPPs in the waveguide arrays show a periodical focusing effect as light illuminates on all waveguides. The oscillation propagating effect, which is similar to the photonic spatial Bloch oscillations in waveguide arrays but is fundamentally different from the Bloch oscillation effect in physics, is also realized as light illuminates on part of the waveguides of the arrays. The theoretical work is carried out by the coupled wave theory and is well demonstrated by the finite-difference time-domain numerical simulations.