Hoffman et al. showed negative refraction at an operating wavelength of 8 µm in a so-called hyperbolic metamaterial consisting of planar, alternating layers (a superlattice) of heavily doped (1–4×1018 cm−3) In0.53Ga0.47As and undoped Al0.48In0.52As deposited by MBE (Hoffman et al., 2007). This metamaterial device was shown to have a performance figure-of-merit of about 20, the highest reported so far. Yet another demonstration is the epsilon-near-zero (ENZ) properties of the InAsSb material when doped heavily. Adams et al. show that heavy doping (1–2×1019 cm−3) of InAsSb causes the real permittivity to cross zero and turn metal-like in the MIR range (Adams et al., 2011). At the zero cross-over of real permittivity (occurring at about 8 µm wavelength), the material behaves as an ENZ material and exhibits special properties such as photon funneling.