▎ 摘　　要

One of the unique features of plasmonic resonances in graphene structures is the enabled tunability through external means. Up to now, electrical gating is extensively adopted to tune graphene plasmonic resonances. This method is, however, limited unfortunately only to graphene structures with electrical connections. Here, a simple and efficient method to tune graphene plasmonic resonances by ultraviolet illuminations in a dynamical and reversible way is demonstrated. It is purely an optical means and can be applied to all kinds of graphene structures without introducing electrodes, ion-gel, or conducting layers required in electrical gating, which is of great significance especially for isolated graphene structures. The optical tuning method could shed new light on graphene-based tunable devices.