Plasmonic enhancement of electric field-induced second harmonic generation in tunneling gaps

Plasmonic nanostructures are able to strongly enhance and localize electromagnetic radiation. In particular, dimer configurations can localize light into the plasmonic gap very effectively and greatly increase the field enhancement due to the excitation of the bonding dipole plasmon (BDP)[1]. The strong enhancement allows to induce nonlinear processes using less powerful light sources [2], so that plasmonic dimers can be a very useful physical system to build nonlinear optoelectronic devices. It is thus desirable to perform rigorous theoretical studies of the nonlinear responses of such systems for future applications.