Enhanced Bragg Reflection in Non-Bravais Superlattice Formed by a Dislocated Teeth-Shaped Plasmonic Waveguide

Abstract

A periodically teeth-shaped surface plasmonic waveguide with dislocation is theoretically investigated. We propose an equivalent solvable model, a four-section non-Bravais lattice with infinite length to describe the dislocated structure. Based on the Bloch theorem, the band gap and Bragg condition of non-Bravais lattice are both derived, and the effect of dislocation on Bragg reflection is discussed. The analysis indicates that the dislocation has a remarkable effect on the distribution of band gaps and gap width and can cause an enhancement of odd-order or even-order Bragg reflection at different filling factors. In addition, the Bragg wavelength can be linearly adjusted by the dislocation. The transmission spectra of a finite-period plasmonic waveguide are studied via both transfer matrix method and numerical simulation at last. The calculation results present two cases for the enhancement of the first-order and the second-order Bragg reflections with different geometric parameters, respectively. The simulation results verify the enhanced Bragg reflection with the increase of dislocation and are well matched with our theoretical analysis.