Lithium niobate (LiNbO₃) crystal is a multifunctional crystal material with excellent physical and chemical properties as well as optical performance. It belongs to the triclinic crystal system. It has high photoelastic sensitivity, high electro-optic coefficient and diffraction efficiency, and excellent chemical-mechanical properties. It is easy to process, has a low cost, and is suitable for mass production. Lithium niobate is widely used in the telecommunications market, such as in mobile phones and optical modulators. It is an optional material for manufacturing surface acoustic wave devices. Other applications include laser frequency doubling, nonlinear optics, Pockel cells, optical parametric oscillator, Q-switched laser, and other acousto-optic effect devices, gigahertz frequency optical switches, etc.