Structured Meta-Mirrors for Beam Spatial Filtering

The work presents optical spatial filtering in reflection based on translationally invariant meta-mirrors. The meta-structure is generated by a thin grating presenting a transverse modulation of the refraction index on the sub-micron scale located in front of a mirror. We analyze the angular spectrum of the reflected waves for different types of structured meta-mirrors as well as the filtering effects of these meta-structures in reflected beams. The comparison between FDTD simulations of full Maxwell equations and different approximated models allows to determine the filtering contribution from the structured cavity and from Mie resonances associated to elements generating the grating.