Second-harmonic light generated by dipole nanoantennas

We investigate the second-order nonlinear response of dipole nanoantennas with narrow gaps. Second-harmonic light originates mainly from weak nonlinear forces acting on free-electrons, such as Lorentz and Coulomb forces, as well as convective and quantum pressure forces. However, dipole nanoantennas provide several mechanisms to magnify such nonlinearities both in the near- and far-field regions