Ultrahigh-efficiency enhancedfour-wave-mixing in Si-Ge-Graphene photonic crystal waveguide

Background: All-optical processing has a huge superiority in speed and efficiency than traditional optical-electrical-optical signal processing. Four-wave-mixing is an important nonlinear parametric process to achieve all-optical processing. Objective: We proposed the photonic crystal waveguide to enhance the conversion efficiency of four-wave-mixingsignificantly in practical application. Methods: We demonstrate a waveguide composed of silicon with mono-layer graphene coated as core and Si-Ge distributed periodically on both sides as cladding. By the introduction of slow light effect of Si-Ge photonic crystal and the localization effect of graphene, the conversion efficiency of four-wave-mixing has enhanced dramatically. Results: The conversion efficiency can be increased by 16dB compared with silicon waveguide and the maximum efficiency as high as -9.1dB can be achieved in the Si-Ge-Graphene photonic crystal waveguide (SGG-PhCWG).The propagation loss can be decreased as small as 0.032dB/cm. Conclusions: Numerical results of proposed SGG-PhCWGmatch well with nonlinear coupled-mode theory. This configuration offers a new physical mechanism and solution for all-optical signal processing and high efficiency nonlinear nanoscale devices.