Semiconductor-dielectric metasurfaces for low-loss field concentrators in the optical range

Plasmonic metamaterials offer a multitude of different applications. A limitation to their wider use is high absorption. Here we consider an alternative solution in the form of silicon-silica nanocomposites to be used as metasurface-based optical concentrators with decreased losses. To this purpose we design and simulate arrays of bowtie nanoantennas, built in ultrathin silicon films on a silica substrate. In comparison to plasmonic structures, field localization is weaker. On the other hand, our structures have very low absorption losses and a full compatibility with standard planar technologies. This makes them convenient for microreactors, lab-on-a-chip devices and various microfluidic MEMS systems.