In this paper, tunable dual plasmon-induced transparency (PIT) is achieved by using a monolayer graphene metamaterial in the terahertz region, which consists of two graphene strips of different sizes and a graphene ring. As the dual PIT effect is induced by the destructive interference between the two quasi-dark modes and the bright mode, we propose a four-level plasmonic system based on the linearly coupled Lorentzian oscillators to explain the mechanism behind the dual PIT. It is proved that the theoretical results agree well with the simulation results. Most importantly, the sensing properties of the designed device have been investigated in detail and we found that it can exhibit high sensitivities and figure of merit (FOM). Furthermore, the dual PIT windows can be effectively modulated by changing the Fermi energy of the graphene layer and the angle of incidence. Thus, the proposed graphene-based metamaterial can hold wide applications for switches, modulators, and multi-band refractive index sensors in the terahertz region.

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Integrating broadband absorption, dynamic tunability, and high optical transparency into a single microwave absorber remains a crucial challenge. Here, an ultra‐broadband, tunable, and transparent microwave meta‐absorber comprising double‐layer indium tin oxide resonant patterns and a water‐based substrate is theoretically presented and experimentally demonstrated. Experimental measurements indicate that the designed meta‐absorber can achieve over 90% absorption in an ultra‐broadband frequency range of 12.49–98.21 GHz with a relative bandwidth of 154.9%, while the average optical transmittance is 60.49%. In addition, a multiple reflections interference model is employed to elucidate the physical mechanisms of the ultra‐broadband absorber. Furthermore, its absorption performance can be reversibly switched between ultra‐broadband and dual‐broadband by altering the water substrate thickness. These peculiar properties make the proposed meta‐absorber more favorable for practical applications in modern stealth materials and optical windows.