Tunable Nonlinear Optical Mesoscopic System Containing Graphene, Optimization of Optical Bistability in THz Frequency

In this paper, a mesoscopic-scaled system is proposed based on the embedded graphene layers inside a dielectric medium in order to improve the presentation of optical bistability in THz range. It is firstly shown that the nonlinearity is considerably enhanced in comparison to the visible range. It is also shown that the nonlinear behavior can be increased by increasing the number of graphene layers. For the purpose of analyzing these issues, we use Boltzmann equation to describe the optical conductivity. Then, THz light wave is traced through the embedded graphene layers via Maxwell equations. This yields the optical bistability hysteresis. The results show that the optical bistability is enhanced with increasing the number of graphene layers. The important issue in THz range is the tunability of nonlinearity with an external bias voltage.