Fig. 1. Structure of the proposed GOS waveguide. (a) 3D view; (b) cross-section view along the red dashed line in (a); (c) fundamental quasi-TE mode electric field distribution of the silicon waveguide; (d) fundamental quasi-TE mode electric field distribution of the GOS waveguide. The light-graphene interaction length is labeled in (a).

Fig. 2. (a) Fabrication processes of the GOS waveguides; (b) SEM images of the GOS waveguides with different interaction lengths.

Fig. 3. (a) Experimental setup for testing the degenerate FWM of the fabricated devices; (b) FWM spectra of the silicon waveguide (black dashed line) and the silicon-graphene strip waveguide with a 60-μm GOS length (red solid line); insets are the zoom-in traces of the pumps and idlers.

Fig. 4. (a) Experimental and calculated conversion efficiencies of the silicon waveguide and the silicon-graphene strip waveguide versus the input pump power; (b) experimental conversion efficiencies of the silicon waveguide (black circle) and the silicon-graphene strip waveguide (red square) versus the signal wavelength; calculated conversion efficiency of the silicon-graphene strip waveguide (blue solid line) versus the signal wavelength.

Fig. 5. (a) Absorption loss of the graphene sheet versus the length of the GOS waveguide; (b) conversion efficiency of the silicon-graphene strip waveguide versus the length of the GOS waveguide.