▎ 摘　　要

Plasmonic sensing based on symmetrical and asymmetrical graphene metamaterials at the infrared region are proposed and investigated numerically by using three dimensional finite-difference time-domain (FDTD) method. The simple unit cell structure is composed of two parallel graphene ribbons and Al2O3 strips. It is shown that transmission resonance dip shifts can be achieved with a variation of the chemical potential of the graphene ribbon.The sensitivity of the proposed metamaterial is also calculated. Our simulations reveal that, by modulating the chemical potential from 0.8 eV to 0.5 eV, a single layer asymmetrical graphene ribbon can achieve a sensitivity of 6500 nm/RIU, compared to 5725 nm/RIU for double layer asymmetrical graphene ribbons. The finding will pave the way towards graphene based tunable devices for sensing in infrared region.