Y:LiNbO3 is a crystal that has been doped with Yttrium ions. LiNbO3, also known as Lithium Niobate, is a widely used crystal in photonics, optical communication, and microwave electronics. The addition of Yttrium ions to the crystal structure can produce unique properties that can be used for specific applications. For example, Yttrium-doped Lithium Niobate has been used as a nonlinear optical crystal for frequency conversion and optical wave mixing applications. The Y:LiNbO3 crystal has also been used in the development of optical waveguides, modulators, and polarizers.