Terahertz plasmonic sensing based on tunable multispectral plasmon-induced transparency and absorption in graphene metamaterials

Graphene surface plasmons have gained wide interest due to their promising applications in terahertz technology. In this paper, we propose an easily implemented monolayer graphene structure, and exploit its quadra resonance mode to achieve triple plasmon-induced transparency (PIT) and triple plasmon-induced absorption (PIA) effects. A uniform theoretical model with four resonators is introduced to elaborate the intrinsic coupling mechanism and examine the accuracy of simulated results. By altering the Fermi energy and the carrier mobility of the graphene, the proposed triple PIT (PIA) system exhibits a dynamically tunable property, and the absorption intensity can be controlled over a broadband frequency range. It is found that the absorption intensity of the triple PIA spectrum can be as high as 50% with four absorption bands, which is 20 times more than that of monolayer graphene. Besides, we further investigate the triple PIT system for terahertz plasmonic sensing applications, and it is shown that the highest sensitivity of 0.4 THz RIU-1 is reached. Thus, the triple PIT system we propose can be employed for multi-band light absorption and plasmonic optical sensing.