Optical nanocomposites containing low refractive index MgF2 nanoparticles Leonid M. Goldenberg, Mathias Köhler, Christian Dreyer, Tohralf Krahl and Erhard Kemnitz Eur. Phys. J. Appl. Phys., 94 1 (2021) 10403 Published online: 06 May 2021 DOI: 10.1051/epjap/2021200298