Compound Dyakonov modes at a symmetric uniaxial-isotropic-uniaxial planar structure

Compound Dyakonov modes supported by a symmetric uniaxial-isotropic-uniaxial planar structure are investigated, of which the uniaxial layers have the identical principal values of the relative permittivity tensor and optic axis orientation. By solving the canonical boundary-value problem, two branches of compound Dyakonov modes are obtained with symmetric and antisymmetric field distributions respectively. The shapes of the field distributions are proven to be closely related to the reflectance of TE polarized waves at the interfaces of the structure. The relevant characteristics of propagation constants, field distributions, propagation direction ranges and polarization states are numerically calculated. The results show that these characteristics are highly affected by the thickness and the permittivity of the middle isotropic layer, the antisymmetric modes will cutoff when the thickness decreases below critical value and the polarization states of symmetric modes will vary significantly from Dyakonov surface waves due to the strong coupling.