The present invention provides an apparatus for propagating
electromagnetic radiation of a selected vacuum wavelength beyond the
diffraction limit. The apparatus comprises a waveguide core and a
cladding disposed about the core. The waveguide core may include a
material with an anisotropic dielectric permittivity, with the optical
axis of the material primarily aligned with direction of light
propagation. In addition, the waveguide core may have a cross-sectional
dimension smaller than about 1/2 of the selected wavelength at least at
one portion of the waveguide core. The cross-sectional dimension of the
waveguide core may decrease along the length of the waveguide core
creating a taper to provide a photonic funnel. The waveguide core may
comprise a homogeneous anisotropic material, anisotropic metamaterial, or
a photonic crystal.