▎ 摘　　要

We study the influence of few-layer graphene on omnidirectional photonic band gap (OPBG) in onedimensional photonic crystal (1DPC) at terahertz frequencies. By periodically introducing few-layer graphene into 1DPC, the width of OPBG can be greatly broadened. As the layer number of introduced graphene increases, the broaden effect of the OPBG becomes stronger. The physical reason behind the broaden effect is that the few-layer graphene acts like an ultrathin metal layer within the frequency range of the OPBG. Besides, the width of the OPBG can be dynamically tuned by the gate voltage of graphene. Compared to 1DPCs containing metal layers, 1DPCs containing few-layer graphene possess lower absorptive loss and more flexible tunability. Our works provides a route and practical way to promote various applications based on tunable terahertz OPBGs.