A Laser based on YLF (yttrium lithium fluoride) crystals, usually Nd:YLF

The term YLF laser is usually used for lasers based on neodymium-doped YLF (Nd:YLF) crystals, although there are other rare-earth-doped YLF crystals, e.g. with ytterbium, erbium, thulium, holmium or praseodymium doping. YLF is the short form for yttrium lithium fluoride (YLiF4). Due to the similar size, yttrium ions can be replaced with rare-earth laser-active ions without strongly affecting the lattice structure.

YLF is birefringent, which eliminates thermally induced depolarization loss.