Large Scale Structure and Cosmological Waveguides
  A sort of gravitational waveguide effect in cosmology could explain some anomalous phenomena which cannot be understood by the current gravitational lensing models as the existence of "twins" objects with similar spectra and redshifts posed on the sky with large angular distance. Furthermore, the huge luminosities of quasars could be explained using filamentary or planar cosmological structures acting as waveguides. We describe the gravitational waveguide theory and then we discuss possible realizations in cosmology. 
S Capozziello and G Iovane