Enhanced Kerr nonlinearity in a quantized four-level graphene nanostructure
Solookinejad Ghahraman, Panahi M, Ahmadi E, Hossein Asadpour Seyyed†,
       

Linear absorption (solid line) and Kerr nonlinearity (dashed line) versus elliptical parameter θ. The selected parameters are the same as Fig. 2.