Non-reciprocity of Faraday rotation in gyrotropic crystals

Abstract

Abstract It is shown that, under the conditions of coexisting natural optical activity and non-zero linear optical birefringence, reversal of the light wave vector sign can result in changing angle of Faraday rotation. Keywords: natural optical activity, Faraday rotation, magnetogyration, non-reciprocity PACS: 33.55.Ad, 78.20.Ls, 78.20.Ek, 78.20.Fm UDC: 535.37 Introduction The effect of additional optical rotation observed earlier in a number of absorbing non-centrosymmetric crystals under the influence of external magnetic field [1–3], which has been explained as a magnetogyration (MG) [4–6], is usually distinguished from the Faraday rotation (FR) via reversing the wave vector of light or rotating a crystal sample by 180 o around the axis perpendicular to the optic axis of the crystal. In relation to this problem, it is worth noticing that the MG as a spatial dispersion effect induced by magnetic field should not, in principle, manifest itself as an optical rotation. Indeed, according to the known Onsager principle, it should lead to changes in the real part of the dielectric permittivity (or the refractive indices), as a result of the so-called ‘