Schematic of the investigated device (a) and its side view (b). The comparison between the numerical absorption spectrum and the analytical one (c). The inset in (c) is
norm of the electric field of the excited graphene surface plasmon mode. The white dashed lines represent the boundaries of the grating, and the yellow dashed line is the
position of the graphene. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)