▎ 摘　　要

A simple quasi-continuous I-type-graphene-based metamaterial with rectangular defect is proposed to realize a dual dynamically tunable plasmon-induced transparency (PIT) and plasmoninduced absorption (PIA) effect. The desired Fermi levels of the monolayer graphene can be dynamically tuned by applying the bias voltage, which can produce the spectral shift of the dual PIT and PIA. What's interesting is that the dual PIT (PIA) can be evolved into the single PIT (PIA) by tuning the distance between two vertical graphene ribbons in the metamaterial. In addition, the distribution intensity and directions of electric field vectors are used to illustrate the distributions of electric field magnitude in the monolayer graphene metamaterial under the action of the polarized incident light. Both theoretical analysis and numerical simulation methods are introduced to study the mechanism of the PIT and PIA effect at terahertz frequency range, and they display very good consistency. Moreover, the surface plasmon polaritons (SPPs) of the monolayer graphene have a better dispersion property and a broad frequency range of the group delay, the maximum group delay of about 0.25 ps is obtained in the proposed metamaterial structure. The proposed metamaterial may have extensive applications in absorbers, tunable switches and slow light devices, et al.