Ultrafast all-optical metamaterial terahertz switch by exploiting nanoparticle-enriched substrate nonlinearity and graphene resonators

Abstract

The emergence of graphene as a new material with several extraordinary optical properties paves a way to introduce new electromagnetic devices in the terahertz (THz) band. In this paper, we have exploited the unique qualities of graphene in combination with the optical Kerr effect in order to propose a new THz switch. In the proposed structure, two graphene layers with circular and notch ring patterns are stacked to obtain two narrowband absorption peaks at the frequencies of 3.65 and 6.5 THz with high absorption values of 92% and 97%, respectively. The imposed pump power in interaction with the nanocomposite substrate provides a controlling mechanism that makes this structure an ideal candidate for all-optical devices in the THz regime. The obtained switching time of the proposed structure is 2 ps, and the maximum extinction ratio of 83% is achieved for the pump power of 273 mW. Moreover, the absorption spectrum of the switch can be manipulated by the chemical potential of graphene layers, which is useful for electro-optical modulation application. The application of the THz switch as an all-optical tunable filter is also studied in this paper.