Second-harmonic generation from singular metasurfaces

TL;DR

This paper provides a theoretical analysis of second-harmonic generation in singular metasurfaces, highlighting their strong light interaction, angle insensitivity, and symmetry-dependent efficiency, with potential applications in all-angle harmonic devices.

Contribution

The study introduces a transformation optics approach to simplify nonlinear response calculations and demonstrates symmetry manipulation to enhance conversion efficiency.

Findings

Strong field enhancement leads to intense surface polarization.

Weak incident angle dependence enables all-angle harmonic generation.

Symmetry breaking improves second-harmonic conversion efficiency.

Abstract

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