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Ultrahigh-efficiency Enhanced Four-wave-mixing in Si-Ge-Graphene Photonic Crystal Waveguide



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.



We proposed the photonic crystal waveguide to enhance the conversion efficiency of
four-wave-mixing significantly in practical application.



We demonstrated 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 the slow
light effect of Si-Ge photonic crystal and the localization effect of graphene, the conversion efficiency
of four-wave-mixing had enhanced dramatically.



The conversion efficiency can be increased by 16dB compared with a silicon waveguide.
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 to 0.032dB/cm.



Numerical results of the proposed SGG-PhCWG matched well with nonlinear coupled-
mode theory. This configuration offered a new physical mechanism and solution for alloptical
signal processing and high-efficiency nonlinear nanoscale devices.
