Graphene hybrid waveguide stimulation using a photoconductive terahertz generator.

Typically, terahertz (THz) surface plasmon polariton (SPP) excitation involves phase-matching engineering and THz plane-wave generation. This requires antennas, lenses, and other optical phase-matching devices. Herein, we demonstrate a novel, to the best of our knowledge, method to excite THz SPPs in graphene directly by using an 800 nm optical pump and a photoconductive source. We miniaturize the SPP excitation setup by eliminating the plane-wave generator and the need for mode matching between the plane wave and the waveguide, thereby improving the power efficiency of THz SPP excitation; an average SPP power of 0.6 mW is obtained for an optical pump power of 25 mW.