Anomalous axial propagation in helicoidal bianisotropic media

Anomalous axial propagation, characterized by axially propagating Voigt waves, in a general linear helicoidal bianisotropic medium (HBM) is examined. A fourth-order ordinary differential equation is derived, from which the conditions for anomalous axial propagation emerge. The analysis is exemplified by application to supercholesteric media, which include cholesteric liquid crystals. In addition, purely dielectric HBMs are considered in detail, with later specialization to chiral smectic dielectric media, and light is shed on the effects of reciprocity and dissipation. (C) 1998 Elsevier Science B.V. All rights reserved.