Excitation of surface plasmons in sinusoidally shaped graphene nanoribbons

One of the key challenges that graphene plasmonics face is achieving efficient coupling to external light. In this paper, this difficulty is overcome by a concept that is capable of exciting localized surface plasmon polaritons (SPPs) in flat gratings formed by sinusoidally shaping graphene nanoribbons. These gratings enable the parallelpolarized light to couple into SPPs, creating a sharp notch with an ultrahigh Q-factor on the transmission spectrum. Besides, the excited SPPs can be tuned not only by adjusting the geometrical parameters (arc length of the sinusoidal grating and the ribbon width) but also by changing the Fermi level of graphene. After reasonably considering the amplitude and period of the 2D grating, both the theoretical analyses and the numerical results demonstrate the applicable properties of this structure. This work provides a framework for understanding the mechanism of plasmon excitations and designing tunable 2D plasmonic devices, such as filters, switches, and sensors. (C) 2016 Optical Society of America