All-dielectric metasurface filters for mid-infrared range

In the present work, a metasurface composed of PbTe spherical particles and located on Ge substrate is considered. We show that it acts in two anti-reflective regimes: depending on geometrical parameters of the structure, it can be a narrow or a wide-range filter. The reason is that the incident radiation excites different dipole resonances of the metasurface. For high-index dielectric materials, we obtain conditions for the validity and accuracy of the dipole approximation and the locations of dipole magnetic and electric resonances. © 2018 Institute of Physics Publishing.All Rights Reserved