Enhanced magnetic Lorentz force second harmonic generation originating from a double-resonances plasmonic metasurface

Artificial second harmonic generation (SHG) based on magnetic Lorentz force has attracted abundant attention from researchers because of the initial breakthrough in physics. It is still a challenging task to boost this type of SHG emission due to the relative lower efficiency and the specific polarization of artificial SHG. Here, we demonstrate an effective way to enhance the magnetic Lorentz force-based SHG in a double-resonances plasmonic metasurface. The design of our method is twofold: firstly, a dark resonance at fundamental frequency and a bright resonance at second harmonic frequency (SHF); secondly, polarization consistency between the bright resonance and the SHF signal. The results demonstrate that the SHF conversion efficiency of this mode-matching plasmonic metasurface can reach 1.4 × 10⁻⁹, which is enhanced by a factor of 5.17 compared to the case without the mode-matching mechanism. This high efficiency and free design of a plasmonic metasurface offer a promising way for the applications of nonlinear optics. (paper)