Fig. 1. Schematic of double-resonance gold dimer array substrate.

Fig. 2. (a) Simulated electric field intensity enhancement factors of the dimer grating (green solid line), the single disk grating (black square line), a single dimer (red circle line), and a single disk (blue triangle line) upon gold film separated by a layer of silica spacer. (b) Ez amplitude at position 2 for the gold dimer array case. (c) Schematics of the four structures simulated.

Fig. 3. (a) Intensity (|E|2) distribution on the half-height surface of the gold disk with hSiO2=45  nm at 785 nm (SPR) with maximum intensity 2042. (b) 950 nm (LSPR) with maximum intensity 7066 corresponding to the two resonant modes of the dimer grating case in Fig. 2(a), respectively.

Fig. 4. (a) Simulated electric field spectrum for the structure with Px=550  nm, Py=500  nm, and d=60  nm at different thicknesses of the silica spacer. (b) Holistic enhancement GSERS via the change of the thickness of the silica spacer.

Fig. 5. Electric field spectrum with Px=550  nm, Py=500  nm, and hSiO2=45  nm at different interparticle separations: 15 nm (black line), 30 nm (red dot-dotted dash line), and 45 nm (blue dotted–dashed line).

Table 1. Normalized Effective Mode Volume and the Quality Factor for Different Interparticle Separation Dimers, a Single Dimer with a Gap of 15  nm, and a Single Disk upon Gold Film Separated by a Layer of Silica Spacer