  Transformation optics gives rise to numerous unusual optical devices, such as
novel metamaterial lenses and invisibility cloaks. Very recently Mattheakis et
al. have suggested theoretical design of an optical waveguide based on a
network of Luneburg lenses, which may be useful in sensing and nonlinear optics
applications. Here we report the first experimental realization of such
Luneburg waveguides. We have studied wavelength and polarization dependent
performance of the waveguides.
