  Connecting lumped circuit elements in a conventional circuit is usually
accomplished by conducting wires that act as conduits for the conduction
currents with negligible potential drops. More challenging, however, is to
extend these concepts to optical nanocircuit elements. Here, following our
recent development of optical lumped circuit elements, we show how a special
class of nanowaveguides formed by a thin core with relatively large (positive
or negative) permittivity surrounded by a thin concentric shell with low
permittivity may provide the required analogy to 'wires' for optical
nano-circuits.
