Plane waves with negative phase velocity in isotropic chiral mediums

The propagation of plane waves in an isotropic chiral medium (ICM) is investigated. Simple conditions are derived-in terms of the constitutive parameters of the ICM-for the phase velocity to be directed opposite to the direction of power flow. It is demonstrated that phase velocity and power flow may be oppositely directed, provided that the magneto-electric coupling is sufficiently strong. (c) 2005 Wiley Periodicals, Inc.