Analysis to closed surface-wave photonic crystal waveguides based on coupled-resonator optical waveguide theory

Traditionally, one can construct a waveguide by introduce defects into surface-wave photonic crystals (SPCs). Here we propose a new structure named closed SPC that can introduce waveguide modes out of photonic bandgap of surface-wave photonic crystal. In this paper, we have comprehensively analyzed dispersion relation, group velocity, normalized transmission and electric field distribution of closed SPC waveguides, and propose several methods to improve performance of the waveguide based on coupled-resonator optical waveguide theory. These methods can improve transmission efficiency from 10% to 60% and eliminate intraband oscillation by adjusting eigenfrequency and coupling factor . These methods are applicable to both single mode and multi mode situations. This letter also paves a new way for improving the performance of other coupled-resonator waveguides.