▎ 摘　　要

We study optical surface second-harmonic generation (SHG) from the plasmonic nanoshells because they can improve and enhance nonlinear optical effects. We also investigate the SHG from the surface of spherical and cylindrical core-shell nanoparticles coated with a strong nonlinear material such as graphene due to its attractive plasmonic behaviour and unique properties of the surface plasmons in graphene. We demonstrate theoretically a giant and tunable second-order harmonic radiation which enhanced through the excitation of the surface plasmon resonance, can be observed at the surface of both spherical and cylindrical nanoshells because of symmetry-breaking at interface, which makes SHG as a valuable and powerful technique for applications in sensing and surface spectroscopy. We present the surface SHG strongly depends on the particle shape and size, the dielectric of embedding medium and core, the type of metal and graphene as a coating nonlinear material.