Analysis of electromagnetic enhancement by a groove doublet in gold substrate.

A semianalytical Fabry-Perot model is presented to investigate the electromagnetic enhancement by double grooves in gold substrate. The influence of hybrid wave (HW) propagating along the metal surface on field enhancement is explored systematically with a HW model. Simulation results imply that the hybrid generated by one groove can affect the mode fields in the other groove after propagating along the metallic surface. Giant electromagnetic field intensity at resonance condition is found for the groove distance of 0.6λ with the contribution of surface waves, which is nearly independent of the incidence wavelength and groove width.