Behaviour of the Poynting vector in uniaxial absorbent media

Abstract

We study the behaviour of the Poynting vector corresponding to the ordinary and extraordinary waves in uniaxial absorbing media. We consider an interface formed by an isotropic non-absorbing media and an anisotropic absorbing one. We verify that when light is incident on the interface, the direction of the Poynting vectors corresponding to the refracted ordinary and extraordinary waves varies with time as in the case of the isotropic absorbing media. In both the ordinary and the extraordinary cases, the tip of the Poynting vector describes an ellipse. In the ordinary case, this ellipse is in a plane parallel to the incidence plane. The centre of the ellipses is given by the temporal average of the ordinary and extraordinary Poynting vectors respectively. Moreover, the time-averaged Poynting vector is never contained in the incidence plane, neither in the extraordinary or in the ordinary case.