TE and TM modes in gyrotropic waveguides

Abstract

An exact analysis of propagation in a gyroptropic waveguide is presented for the special case of the DC magnetic field normal to the direction of propagation and tangential to the plane of the film; this is found to support pure TE and TM modes. Expressions for the propagation constants in terms of the permittivity tensor elements are derived. The TM modes depend on the off-diagonal element and one of the diagonal elements, while the TE modes depend only on the second diagonal element. Numerical results computed for a YIG film on a GGG substrate show that the effect of the off-diagonal element is negligible but any difference in the value of the diagonal elements affects significantly the relation between the TE and TM mode spectra.