Second-Harmonic Generation in Lithium Niobate Metasurfaces

Lithium niobate (LN), a birefringent crystal, is an attractive material for nonlinear photonics due to its wide transparency range and high second-order nonlinearity. Among other applications, it has been used for fabrication of fast optical modulators and nonlinear frequency converters. However, almost all implementations to date were using bulk LN crystals or waveguides. Although isolated Mie-type nanoresonators in lithium niobate have been shown very recently [1], functional metasurfaces based on densely packed arrangements of such nanoresonators have not yet been demonstrated. In order to close this gap, we have designed, fabricated and experimentally investigated a nonlinear metasurface consisting of an array of nanocubes featuring Mie-type resonances.