Reconfigurable double-band valley topological edge states through rotating the dielectric rod with holes in triangular lattice

Abstract

The valley topological edge states (VTESs) have become a new research hotspot in topological photonics because of its flexibility and diversity. The major challenge for them comes from the dynamical modulation and the weak ability of direction-locked. In this paper, a triangular lattice made of rotatable dielectric rods with three circular holes is designed. Through the rotation of rod, the lifting of the valley points leads to double nontrivial bandgaps and double-band VTESs. The spin-locked excitation of the VTESs, is dependent on whether the nontrivial bandgaps is closed by the VTESs. The reconfigurable VTESs have been achieved with the idea of programmable coding, which provides potential applications in on-chip photon routing. • A triangular lattice made of rotatable dielectric rods with three circular holes is constructed. • The double-band valley topological edge states are achieved. • The valley topological edge states are reconfigurable with the idea of programmable coding.