Structure of the Maxwell equations in the region of linear coupling of electromagnetic waves in weakly inhomogeneous anisotropic and gyrotropic media
Federal Research Center Institute of Applied Physics of the Russian Academy of Sciences, ul. Ulyanova 46, Nizhny Novgorod, 603000, Russian Federation
Linear coupling of electromagnetic waves in weakly inhomogeneous non-one-dimensional media is considered as a manifestation of the polarization degeneracy of the Maxwell equations. It is shown that the presence of two polarization-degenerate normal waves imposes strong constraints on the dielectric tensor components near the interaction region. As a result, the possible types of linear wave coupling and the corresponding wave equations admit a universal classification, which is independent of the way in which the linear medium is modeled.