Title: Third Harmonic THz Generation from Graphene in a Parallel-Plate Waveguide,
Abstract: Graphene as a zero-bandgap two-dimensional semiconductor with a linear
electron band dispersion near the Dirac points has the potential to exhibit
very interesting nonlinear optical properties. In particular, third harmonic
generation of terahertz radiation should occur due to the nonlinear
relationship between the crystal momentum and the current density. In this
work, we investigate the terahertz nonlinear response of graphene inside a
parallel-plate waveguide. We optimize the plate separation and Fermi energy of
the graphene to maximize third harmonic generation, by maximizing the nonlinear
interaction while minimizing the loss and phase mismatch. The results obtained
show an increase by more than a factor of 100 in the power efficiency relative
to a normal-incidence configuration for a 2 terahertz incident field.