Second-harmonic generation from singular metasurfaces

We present a theoretical study of second-harmonic generation from singular metasurface. The metasurfaces strongly interact with the incident light, where large field enhancement forms an intense surface polarization that generates field. By using transformation optics, calculation nonlinear optical response is converted metasurface frame to simple slab geometry, largely reducing complexity problem. In addition, exhibits weak dependence on angle which can be potentially used as all-angle device for harmonic generations. Finally, we symmetry in far and show how enhance conversion efficiency under normal incidence by breaking inversion symmetry.