▎ 摘　　要

Nanofocusing and deceleration of terahertz plasma waves in tapered metal-insulator-graphene heterostructure is studied theoretically. It is shown that, choosing an appropriate value of taper length for given values of the taper angle and the Fermi energy in a doped or gated graphene, the plasma wave energy density value in the vicinity of the taper apex exceeds its value in the taper inlet cross-section by tens of percent in spite of the Drude losses in graphene. 'Fhe plasma wave decelerates while moving toward taper apex and its energy velocity becomes several times smaller as compared to that in the taper inlet cross-section.