Plasmonic resonance with Fano lineshape has attracted a great deal of recent interest. Here we design a new structure with a dimer grating upon a gold film separated by a layer of silica spacer, which has two resonant modes corresponding to the dimer’s localized surface plasmon resonance and the surface plasmon resonance excited by the dimer grating. This structure has three advantages for near-infrared detection in water. First, it provides two resonant modes to enhance the excitation and scattered signals of surface-enhanced Raman scattering. Second, coupling of these two modes results in a Fano resonance, providing a higher electric field enhancement. Finally, the dimer provides more flexible tunability compared to a single disk structure.