Directional control of propagating graphene plasmons by strain engineering

Abstract

Control of propagating surface plasmon on a scale beyond the diffraction limit is important for the development of integrated nanophotonic circuits and optical information technology. In this paper, a strain-based modulation mechanism for directional control of propagating graphene plasmons was proposed. We demonstrated numerically that the GPs can be directionally controlled by the implementation of strain on graphene. The topologies of GPs excited by a z-polarized optical emitter in unstrained and strained graphene were illustrated both in real space and momentum space. When imposing strain engineering to graphene in different directions with a different modulus, multi-dimensional control of GPs in any direction can be realized. The simulated propagation length ratio η of the GPs can reach 3.5 when the strain with a modulus of 0.20 is applied along or perpendicular to the zigzag direction of graphene. Besides, the effect of PDMS on GPs was investigated finally for the experiments to be carried out and we show that the PDMS does not affect the generation of directional GPs under strain engineering. Our proposed directional control of GPs not only has the advantages of wide operating wavelength but does not require additional coupling mechanisms, which is beneficial to the design of integrated photonic devices.