▎ 摘　　要

The power conversion of a terahertz wave normally incident on a periodic graphene structure to propagating-plasmon power is theoretically studied. The conditions of the maximum conversion of the incident radiation power to the propagating-plasmon power and excitation condition of unidirectional traveling plasmon are determined. It is found that up to 15% of the incident wave power can be converted to propagating-plasmon power.