Experimental observation of plasmons in a graphene monolayer resting on a two-dimensional subwavelength silicon grating

We experimentally demonstrate graphene-plasmon polariton excitation in a continuous graphene monolayer resting on a two-dimensional subwavelength silicon grating. The subwavelength silicon grating is fabricated by a nanosphere lithography technique with a self-assembled nanosphere array as a template. Measured transmission spectra illustrate the excitation of graphene-plasmon polaritons, which is further supported by numerical simulations and theoretical prediction of plasmonband diagrams. Our grating-assisted coupling to graphene-plasmon polaritons forms an important platform for graphene-based opto-electronics applications.