▎ 摘　　要

In this article, we present a theoretical analysis of the optical bistability phenomenon of the transmitted light beam in a graphene-based one-dimensional photonic crystal heterostructure in terahertz frequency range. This low-threshold optical bistability originates from the enhancement of the local electric field owing to the excitation of topological edge state at the interface between the two proposed one-dimensional photonic crystals. The results of calculation and simulation show that the hysteretic behavior and the threshold of optical bistability can be adjusted continuously by changing the applied voltage of the graphene. Moreover, the optical bistability of this structure also can be modified by the angle of the incident light and the number of graphene layers. Our findings provide a new method for realizing low threshold and tunable optical bistability in terahertz range, indicating excellent application prospects in the field of all-optical switches and other optical bistable devices.