  The fundamental guided electromagnetic dispersion characteristics in lossless
dispersive metamaterial clad circular air hole waveguides are investigated. Two
operating guided modes are found to exist: circular waveguide and surface
plasmon polariton modes that support fast and slow waves, respectively. Hybrid
mode classifications are also made in an empirical manner so that the guided
modes can be sorted into either TM-like or TE-like modes in terms of their
unique dispersion characteristics. Unusual dispersion characteristics,
including multi-valued propagation constants at a single frequency, backward
waves, and subwavelength guided propagations, are observed and discussed in
relation to the air-hole radii and dielectric and magnetic constants of the
metamaterial clad. A discussion comparing the extraordinary dispersion
characteristics with those of other dielectric, plasmonic, and metamaterial
waveguides is also included.
