Dielectric Chiral Metasurfaces for Second‐Harmonic Generation with Strong Circular Dichroism

Abstract Dielectric chiral metasurfaces can generate harmonic waves with high efficiency and strong circular dichroism (CD), when they are supported by metallic substrates. Numerical results show that the second‐harmonic generation (SHG) efficiency of about 10 −3 % for a peak pump intensity of about 5 GW cm −2 can be achieved in the blue‐UV, and the SHG CD reaches up to about 1.8, from a metasurface of Z‐shaped lithium niobate nanoantenna array supported by gold substrate. Highly efficient and strong circular dichroic nonlinear responses are attributed to the plasmon‐assisted local field enhancement in the dielectric chiral nanoantennae adjacent to the metallic substrate.