Lithium niobate metasurfaces: preparation and photonics applications

As derivatives of 3D metamaterials, artificial metasurface structures with sub-wavelength thicknesses can flexibly manipulate light-matter interactions in a compact manner, which is beneficial for the fabrication of multi-functional and ultracompact photonic devices. Therefore, metasurface structures are of great significance for micro-nano photonics and integrated photonics. The ferroelectric crystal lithium niobate is regarded as one of the most promising multifunctional integrated photonic platforms due to its wide transparent window spanning from the visible to the mid-infrared band as well as large nonlinear optical and electro-optic coefficients. In recent years, research on integrated photonics devices based on lithium-niobate-on-insulator (LNOI) thin films has also been developed rapidly. In this paper, several micro-nano processing technologies that have the potential to prepare high-quality lithium niobate metasurfaces are summarized. At the same time, the research progress of lithium niobate metasurface structures in recent years is introduced, and its future research directions are prospected.