Transformation optics, isotropic chiral media, and non-Riemannian   geometry
  The geometrical interpretation of electromagnetism in transparent media (transformation optics) is extended to include media with isotropic, inhomogeneous, chirality. It is found that such media may be described through introducing the non-Riemannian geometrical property of torsion into the Maxwell equations, and shown how such an interpretation may be applied to the design of optical devices. 
S. A. R. Horsley
physics.optics