WAVE PROPAGATION IN STRATIFIED ABSORBING OR AMPLIFYING MEDIA

Expressions are derived for the amplitudes and phases of the fields associated with the electromagnetic waves propagating through an isotropic stratified absorbing medium capable of an irreversible exchange of energy with the radiation field. These solutions are obtained for media in which the inhomogeneity consists of a slow variation of the relevant material parameters along one particular direction in space. The mechanism by which energy is dissipated in matter may involve the conductivity of the medium or by magnetic- dipole allowed transition in the medium.