Yttrium lithium fluoride (LiYF₄, sometimes abbreviated YLF) is a birefringent crystal, typically doped with

neodymium Neodymium is a chemical element with the symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth metals. It is a hard, slightly malleable, silvery metal that quickly tarn ...

praseodymium Praseodymium is a chemical element with the symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered to be one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for i ...

and used as a gain medium in

solid-state laser A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class ...

s. Yttrium is the substitutional element in LiYF_4. The hardness of YLF is significantly lower than other commons crystalline laser media, i.e. yttrium aluminium garnet.

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See also