Undoped YVO₄ crystal is an excellent birefringence optical crystal developed newly. It has very good transmission in a wide wavelength range from visible to infrared, large index of refractivity and birefringence difference. Compared with other important birefringence crystals, YVO₄ crystal has higher hardness, better fabrication property, water insoluble and man-made than calcite (CaCO₃ single crystal); easier to get large, high quality crystal and lower cost than rutile (TiO₂ single crystal). Those outstanding properties make YVO₄ crystals very important birefringence optical material and widely used in opto-electronic research, development and industry. For example, the optical communication system needs a huge quantity devices of undoped YVO₄  crystal such as fiber optical isolators, circulators, beam displacers, Glan polarizers and other polarizing devices.