The lithium niobate crystal is a multifunctional optical material with excellent comprehensive properties. For the past decades lithium niobate crystal has attracted significant attention in optics researches. Recently lithium niobate oninsulator LNOI also known as lithium niobate thin film LNTF has been considered as a revolutionary technology in optics that rejuvenates lithium niobate for LNOI-basedintegrated photonics. A LNTF is irreplaceable in frequency conversion since it is one ofthe best nonlinear crystals.