Simultaneous negative- and positive-phase-velocity propagation in an isotropic chiral medium

The phase velocity of plane waves propagating in an isotropic chiral medium can be simultaneously positive for left-circularly polarized light and negative for right-circularly polarized light (or vice versa). The constitutive parameter regimes supporting this phenomenon are established for nondissipative and dissipative mediums. The boundary between positive- and negative-phase velocity is characterized by infinite phase velocity. (c) 2007 Wiley Periodicals, Inc.