A technology has been developed for the production of large active elements made from KGSS 0180/35 neodymium phosphate glass (with a neodymium ion concentration of NNd53.5 x1020cm-3), iintended for powerful pulsed lasers with high output radiation energy. The neodymium glasses were melted using a two-stage or single-stage process with high-purity reagents in crucibles made from dispersion-strengthened platinum or a newly developed highstrength cristobalite refractory, which, along with other process methods, makes it possible to obtain glass that contains no metallic platinum inclusions. The main elements of the process for synthesizing neodymium glass are deep oxidation of the melt with dry oxygen in order to convert traces of platinum and iron to higher valence states and simultaneously eliminate hydroxyl group impurities, as well as the use of a nonplatinum refractory to fabricate the glassware. The resulting glasses are characterized by high optical homogeneity, high luminescence lifetime of the neodymium ( t~300 us), radiation strength to 33 J/cm2 when the exciting pulse width is 3?4 ns, and a nonactive absorption coefficient at the lasing wavelength of about 0.0015 cm-1. The required high-quality surface processing of the active elements is provided by fine annealing of the blanks and by using grinding?polishing equipment with program control.
V. I. Arbuzov, S. G. Lunter, S. I. Nikitina, G. T. Petrovskii, A. D. Semenov, Yu. K. Fedorov, V. S. Shashkin, A. V. Shashkin, V. M. Volynkin, V. Ya. Ponomarev, V. S. Sirazetdinov, and A. V. Charukhchev, "Large disc-shaped active elements made from neodymium phosphate glass elements made from neodymium phosphate glass," J. Opt. Technol. 70, 361-369 (2003)