Surface-enhanced coherent anti-Stokes Raman scattering based on coupled nanohole-slit arrays.

Metal nanohole arrays show excellent performance when applied for sensing, optical fibers, and surface-enhanced spectroscopy, but they are not ideal candidates for surface-enhanced coherent anti-Stokes Raman scattering (SECARS) because of their low enhancement factor (EF). Here, the finite element method was used to study the dependence of the period, width, and thickness of nanoslits on the EF of SECARS and optical transmission in Au nanohole-slit arrays. Nanoslits across the nanoholes significantly modulated the SECARS signal, and we observed an ∼10 improvement in the EF of SECARS compared with the nanohole-only structure.