  The active and nonlinear graphene properties are limited due to weak light
matter interaction between the ultrathin graphene and the incident light. In
this work, we present enhanced nonlinear effects at the low terahertz (THz)
range by designing a new patterned graphene hyperbolic metamaterial (GHMM).
More specifically, it is demonstrated that the third harmonic generation (THG)
can be significantly enhanced by the proposed GHMM due to the field enhancement
at the resonance as well as the supported slow light response that fosters
strong light matter interaction.
