Efficient Chiral Nonlinear Metasurface Based on Lithium Niobate

There have been many researches on nonlinear metasurface in recent years. The advantages of lithium niobate are its transparency in the near infrared range as well as high nonlinear coefficients. In this letter, a metasurface based on the chiral structure of lithium niobate is designed. The nonlinear efficiency can reach 3.9% with optical intensity at 0.0561 GW/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. It can also achieve a circular dichroism (CD) of 0.79 under the same nonlinear conditions. The resonance principle is analyzed by using multipole decomposition. The chiral structure increases the degree of freedom of structural adjustment and realizes the differential response to different circularly polarized light. The excellent comprehensive effect of our research can make it applicable to biosensing, nonlinear imaging, encoding, and chiral light modulation.