In this paper, a new electro-optical switch modulator based on the surface plasmon polaritons of graphene is proposed. An air–graphene-substrate–dielectric structure is adopted in the modulator. In this structure, the graphene is considered as a film of metal whose thickness tends to be infinitesimal. By changing the external voltage, the boundary conditions can be changed to decide whether the surface plasmon polariton waves can be excited in mid-infrared band. Because of this effect, the structure can be used as an electro–optical switch modulator, whose modulation depth is about 100% in theory. Finally, the 3 dB bandwidth (~34 GHz) and the energy loss (36.47 fJ/bit) of the electro–optical switch modulator are given, whose low energy loss is very suitable for engineering applications.

Phase modulation of light is the core of many optoelectronic applications, such as electro-optic switch, sensors and modulators. Graphene Surface plasmon polaritons (SPPs) exhibit unique properties in phase modulation including dynamic tunability, a small driving voltage and small device size. In this paper, the novel phase modulation capability of graphene SPPs in mid-infrared are confirmed through theory and simulation. The results show that graphene SPPs can realize continuous tuning of the phase shift at multiple wavelengths in mid-infrared, covering the phase range from 0° to 360°. Based on these results, a sandwich waveguide structure of dielectric–graphene–dielectric with a device length of 800 nm is proposed, which shows up to 381° phase modulation range at an operating wavelength of 6.55 µm, given a 1 V driving voltage. In addition, the structure size is much shorter than the wavelength in mid-infrared and can realize sub-wavelength operation. This work paves the way to develop graphene-based tunable devices for mid-infrared wave-front control.

Facing the problems of ohmic loss and short propagation length, the application of plasmonic waveguides is limited. Here, a triangle hybrid plasmonic waveguide is introduced, where a cylinder silicon waveguide is separated from the triangle prism silver waveguide by a nanoscale silica gap. The process of constant optimization of waveguide structure is completed and simulation results indicate that the propagation length could reach a length of 510 μm, and the normalized mode area could reach 0.03 along with a high figure of merit 3150. This implies that longer propagation length could be simultaneously achieved along with relatively ultra-deep subwavelength mode confinement due to the hybridization between metallic plasmon polarization mode and silicon waveguide mode, compared with previous study. By an analysis of fabrication errors, it is confirmed that this waveguide is fairly stable over a wide error range. Additionally, the excellent performance of this is further proved by the comparison with other hybrid plasmonic waveguides. Our work is significant to manipulate light waves at sub-wavelength dimensions and enlarge the application fields, such as light detection and photoelectric sensors, which also benefit the improvement of the integration of optical devices.

This paper analyzes graphene irradiation effects using a molecular dynamic simulation software, large-scale atomic / molecular massively parallel simulator (LAMMPS). We propose a hypothesis for the effective range of incident ions based on simulation results of irradiation effects that were found using a suspended single-layer graphene. This explains the influence mechanism of irradiation density on the degree of material defects. This paper does key research on how copper substrate influences a single- and bi-layer graphene. The results show that for a single-layer graphene (SLG) the substrate increases the effective range of the incident ions. Within a certain range of the irradiation density, the substrate enhances the defect production on graphene in low-energy irradiation (<5 keV). However, due to the shielding effect of the substrate, the overall trend of graphene damage will be reduced. For the bi-layer graphene (BLG), the effect of the indirect action range is more obvious than that of the direct-action range. In the case of low irradiation density, the knock-on atoms of BLG are much less than suspended SLG.