Numerical Analysis of Nanogap Effects in Metallic Nano-disk and Nano-sphere Dimers: High Near-field Enhancement with Large Gap Sizes

Various gap sizes are investigated numerically to extract the local electric field enhancement from a gold sphere and disk dimer systems. Our simulations predict that a metallic disk dimer system(s) exhibit large local electric field enhancements at larger gap sizes (20 nm, 40 nm) as compared to that of sphere dimer designs (gap size = 8 nm, 14 nm). These gap size differences ~ 2.5 -3.3 times larger as compared to that of sphere dimer systems, facilitates the device fabrication. These numbers are obtained by the influence of uniform gap size distribution as a function of total volume “±Z direction”. Such geometry, by achieving good local electric field enhancement from larger gap size, will enhance the variety of potential applications in the field of plasmonics, sensors, single molecule detection, surface enhanced spectroscopy, and so on.