▎ 摘　　要

Graphene plasmonics has recently attracted remarkable attention, with reports of numerous intriguing properties and novel device demonstrations. As a two-dimensional (2-D) semimetal with ultrahigh carrier mobility, graphene can host plasmon waves that exhibit extremely tight spatial confinement, exceptionally long plasmon lifetime, and an electrostatically tunable response in the mid-infrared (mid-IR) and terahertz (THz). These properties render graphene a viable plasmonic material for achieving novel functionalities in various mid-IR to THz photonic systems. From the device perspective, we review the key distinguishing features of graphene plasmons and highlight the latest developments, such as mid-IR and THz tunable infrared sources, modulators, and photodetectors. Finally, we discuss future challenges and new opportunities for graphene plasmonics in infrared photonic systems.