Controlling Transition Photonic Band with Synthetic Moiré Sphere

Abstract In recent years, twisted bilayer graphene has become a hot topic and inspired the research upsurge of photonic moiré lattice. Here, we designed a photonic moiré superlattice with two synthetic twist angles and constructed a synthetic moiré sphere based on these two angles. Thus, we have more degrees of freedom to modulate the band structure flexibly. A new type of transition photonic bands (TPBs) can be produced in such a moiré superlattice. We investigate the influence of two twist angles on TPBs and find a series of magic angle pairs with optimal band compression of TPB. The interesting optical properties of TPBs are experimentally demonstrated, including pulse delay, nonlinear optical enhancement and pulse width compression. Our work introduces a new path to explore multi-twist angles moiré superlattices and reveals that the reported photonic moiré superlattice based on moiré spheres has broad application prospects including nonlinear optics processes and other light-matter interactions.