Second harmonic generation manipulation enabled by electromagnetic coupling in bianisotropic metamolecules

Abstract

Bianisotropic metamolecules provide a novel opportunity to realize optical magnetism through localized electromagnetic coupling (EM coupling). Previous investigations of the EM coupling, however, are mostly limited to linear regime. In this work, active manipulation of light in nonlinear regime with EM coupling is theoretically studied. To this end, a bianisotropic metamolecule composed of four uniform gold nanodisks is designed. Simulation results show that a Fano-like resonance induced by EM coupling is sufficient to control the second harmonic generation (SHG) signal. By rotating polarization angle of optical excitation source, the emitted SHG signal is switched on–off with the EM coupling. Furthermore, modulation of the SHG signal is demonstrated through the EM coupling by tuning the gap size and filling material.