Negative-index dispersion and accidental mode degeneracy in an asymmetric spoof–insulator

Negative-index dispersion and accidental mode degeneracy in an asymmetric spoof–insulator–spoof waveguide

Tian Li-li¹, Liu Jian-long¹, Zhou Ke-ya¹, Gao Yang², Liu Shu-tian^{1, †}

(color online) (a) Dispersion relations of coupled modes on the symmetric SIS waveguides. The solid and dashed curves denote the symmetric and anti-symmetric modes, respectively. (b)–(c) H_z distributions on a unit cell of the symmetric SIS waveguide at asymptotic frequencies when (b) s = 0.2d and (c) s = 0.3d. The left and right panels at each subgraph represent the symmetric and anti-symmetric modes, respectively. d = 1 mm, t = 0.018d, g = 0.2d, a = 0.3d, h = d, and w = 1.2d.