General Expression of the Poynting Vector Appropriate for Evanescent Wave Region: Intrinsic Function in the Method of Single Expression

摘要

An alternative expression for the Poynting vector valid for region of evanescent waves is presented. This expression is the intrinsic function in the method of single expression (MSE). The MSE does not exploit superposition principle, i.e. does not represent solutions of Helmholtz's equation as the sum of counter-propagating waves, which permits to have alternative expression for the Poynting vector valid both in media with a positive product of permittivity and permeability, and at a negative product (relevant to evanescent waves) as well. The boundary problem solution by the MSE permits to observe spatial distributions in a confined medium not only for electric and magnetic field amplitudes, but also for the Poynting vector. The alternative expression for the Poynting vector is in perfect agreement with the traditional representation for propagating waves.