Second Harmonic Generation Manipulation Enabled byElectromagnetic Coupling in Bianisotropic Metamolecules

摘要

Bianisotropic metamolecules provide a novel opportunity to realize opticalmagnetism through localized electromagnetic coupling (EM coupling). Previousinvestigations of the EM coupling, however, are mostly limited to linearregime. In this work, active manipulation of light in nonlinear regime with EMcoupling is theoretically studied. To this end, a bianisotropic metamoleculecomposed of four uniform gold nanodisks is designed. Simulation resultsshow that a Fano-like resonance induced by EM coupling is sufficient to controlthe second harmonic generation (SHG) signal. By rotating polarizationangle of optical excitation source, the emitted SHG signal is switched on–offwith the EM coupling. Furthermore, modulation of the SHG signal is demonstratedthrough the EM coupling by tuning the gap size and filling material.