All-dielectric KTiOPO4 metasurfaces based on multipolar resonances in the terahertz region.

We employ ferroelectrics to study the multipolar scattering in all-dielectric metasurfaces based on KTiOPO4 (KTP) micro-disks for efficient manipulation of electromagnetic waves in the THz spectral region (0.6-1.5 THz). By adjusting the aspect ratio of the disks near the multipolar resonances, we show that the KTP disk array can form a multifunctional metasurface that covers the entire range of the electromagnetic response with resonantly enhanced anisotropic properties. The proposed ferroelectric metasurfaces will provide a versatile platform to manipulate THz waves, and open possibilities to monolithically combine it with THz generation.