Liquid crystal hyperbolic metamaterial for wide-angle negative-positive   refraction and reflection
  We show that nanosphere dispersed liquid crystal (NDLC) metamaterial can be characterized in near IR spectral region as an indefinite medium whose real parts of effective ordinary and extraordinary permittivities are opposite in signs. Based on this fact we design a novel electrooptic effect: external electric field driven switch between normal refraction, negative refraction and reflection of TM incident electromagnetic wave from the boundary vacuum/NDLC. A detailed analysis of its functionality is given based on effective medium theory combined with a study of negative refraction in anisotropic metamaterials, and Finite Elements simulations. 
G. Pawlik, K. Tarnowski, W. Walasik, A.C. Mitus, I.C. Khoo
physics.optics