Kerr-type nonlinear response of a graphene-coated quasiperiodic structure composed of silicon dioxide and polystyrene layers in the THz region

In the terahertz frequency domain, we theoretically attempt to determine some properties of kerr-type nonlinear response of a graphene-coated one-dimensional quasiperiodic structure based on Fibonacci sequence. The supposed structure is constituted by silicon dioxide and nonlinear polystyrene dielectrics where graphene sheets are located between them. The calculations are accomplished by using standard transfer matrix method. Our numerical results demonstrate that the introduction of graphene sheets in the structure has an important role in reducing bistability thresholds. It is found that for both TE and TM waves the switching-up and switching-down thresholds of bistability are reduced in comparison to without graphene case. In addition, the threshold values of TM mode are less than those of TE one. Also, by manipulating parameters such as graphene chemical potential, graphene damping constant and sequence number of structure, some other interesting features are achieved. This paper provides a way to reduce bistability thresholds which are of optical switching issues.