Crystal growth and spectroscopic studies of Nd-doped apatite crystals as active media for 944.11-nm laser

We have grown neodymium doped mixed apatite crystals, (SrxBa1- x)5(PO4)3F, Sr5(P1-xVxO4)3F, and Ba5(P1-xVxO4)3F, and spectroscopically studied them as potential gain media for a laser source for atmospheric water sensing operating at 944.11 nm. We conclude that an appropriate apatite host material for a 944.11 nm laser should be a mixture of Sr5(PO4)3F with a small fraction of Ba5(PO4)3F. The precise wavelength tuning around 944.11 nm can be accomplished by varying the host composition, temperature, and threshold population inversion. In apatite crystals of mixed composition, the amplified spontaneous emission loss at 1.06 micrometers is predicted to be significantly smaller than that in the end members.