A double-grating surface-enhanced Raman spectrometer. The spectrometer includes a substrate; a plurality of nanofingers carried by the substrate, the nanofingers arranged to define a first optical grating; a light source oriented to project a beam of light toward the first optical grating; a second optical grating oriented to receive a beam of light scattered from the first optical grating; and a detector oriented to receive a beam of light scattered from the second optical grating.