Neodymium-doped yttrium lithium fluoride
Neodymium-doped yttrium lithium fluoride (Nd:YLF) is a lasing medium for arc lamp-pumped and diode-pumped solid-state lasers. The YLF crystal (LiYF) 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 s, 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.