Tuning the degeneracy order of Dirac-like point by valley engineering in phononic and photonic superlattices

Abstract

We propose a compound structure with three triangular sublattices to achieve arbitrary accidental degeneracies of band crossing in their phononic and photonic band structures. Dirac-like points are tuned by a method of valley engineering folding high symmetric K points belong to different valleys to the Γ point of the Brillouin zone center. The degeneracy orders are varied from four-fold to triple-fold and double fold at Γ point in their phononic and photonic band structures. This can be of interest in designing high order of Dirac-like point for manipulating acoustic waves or light at a certain frequency.