Eigenvalues analysis for EM waves in anisotropic materials and its applications for unidirectional transmission and unidirectional invisibility

We conduct a comprehensive analysis of the eigenvalues for propagation of electromagnetic (EM) waves in anisotropic materials. The analysis can be employed to judge the characteristics of the eigenvalues for EM waves in anisotropic materials. Taking the advantage of the non-opposite eigenvalues, we show that unidirectional transmission and unidirectional invisibility can be realized with a slab of natural anisotropic material. Our results in this work may provide important guidelines for design of novel devices of unidirectional transmission or unidirectional invisibility.