Neodymium-doped yttrium lithium fluoride

Neodymium-doped yttrium lithium fluoride (Nd:YLF) is a lasing medium for arclamp-pumped and diode-pumped solid-state lasers. The YLF crystal (LiYF4) is naturally birefringent, and commonly-used laser transitions occur at 1047 nm and 1053 nm.

It is used in Q-switched systems in part due to its relatively long fluorescence lifetime. As with YAG lasers, harmonic generation is frequently employed with Q-switched Nd:YLF to produce shorter wavelengths. A common application of frequency-doubled Nd:YLF pulses is to pump ultrafast Ti:Sapphire chirped-pulse amplifiers.

Neodymium-doped YLF can provide higher pulse energies than Nd:YAG for repetition rates of a few kHz or less. Compared to Nd:YAG, the Nd:YLF crystal is very brittle and fractures easily. It is also slightly water-soluble — a YLF laser rod may very slowly dissolve in cooling water which surrounds it.