  We study linear guided waves propagating in a slab waveguide made of a
negative-refraction- index material, the so-called left-handed waveguide. We
reveal that the guided waves in left-handed waveguides possess a number of
peculiar properties, such as the absence of the fundamental modes, mode double
degeneracy, and sign-varying energy ux. In particular, we predict the existence
of novel types of guided waves with a dipole-vortex structure of the Pointing
vector.
