The spatial plasmonic Bloch oscillations in nanoscale three-dimensional surface plasmon polaritons metal waveguide...

In this paper, the dynamic motion of surface plasmon polaritons, spatial Bloch oscillations, in a kind of nanoscale three-dimensional surface plasmon polaritons metal waveguide arrays is presented. The waveguide arrays are composed of 41 three-dimensional plasmonic waveguides with ultra-small cross section, thus the maximum lateral size of the waveguide arrays is only 6.56µm. The gradient of surface plasmon ploartions propagation constants across the waveguide arrays is realized by gradually changing the refractive index of the dielectric layer in the waveguide arrays. Theoretical results from the coupled wave theory show that surface plasmon polaritons propagate in the three-dimensional metal waveguide arrays as breathing and transverse oscillatory mode Bloch oscillations under the conditions of single and multiple waveguide excitations, respectively. All theoretical results are confirmed by finite-difference time-domain numerical simulations. Through the numerical analysis of fabrication tolerance caused by the metal strips uniform shifts, the designed three-dimensional surface plasmon polaritons metal waveguide arrays can resist certain fabrication errors.