Excitation theory for space-dispersive active media waveguides

Abstract

A unified electrodynamic approach to the guided-wave excitation theory is\ngeneralized to the waveguiding structures containing a hypothetical\nspace-dispersive medium with drifting charge carriers possessing simultaneously\nelastic, piezoelectric and magnetic properties. Substantial features of our\nelectrodynamic approach are: (i) the allowance for medium losses and (ii) the\nseparation of potential fields peculiar to the slow quasi-static waves. It is\nshown that the orthogonal complementary fields appearing inside the external\nsource region are just associated with a contribution of the potential fields\ninherent in exciting sources. Taking account of medium losses converts the\nusual orthogonality relation into a novel form called the quasi-orthogonality\nrelation. It is found that the separation of potential fields reveals the fine\nstructure of interaction between the exciting sources and mode eigenfields: in\naddition to the exciting currents interacting with the curl fields, the\nexciting charges and the double charge (surface dipole) layers appear to\ninteract with the quasi-static potentials and the displacement currents,\nrespectively.\n