Symmetry-engineered band structure in two-dimensional multiferroic photonic crystals

Abstract

In two-dimensional photonic crystals composed of the multiferroic terbium manganite (TbMnO3) crystal cylinders, we selected three-, four-, and six-fold spatial rotational symmetries to design the artificial lattice structure. Compared with two others, the six-fold symmetry opens and even widens the absolute bandgap in the far-infrared waveband at higher frequencies. When a static magnetic field is applied, it induces the broken time-reversal symmetry, which, in turn, arrows the bandgap. In all cases, the topological phase is robust. This symmetry engineering highlights an engineering strategy for photon-subclass far-infrared detectors, by magnetically manipulating the on-off state of absolute photonic bandgaps.