The phosphate neodymium-doped glasses with low nonlinear refractive index coefficient (1(DOT)10-13SGSE) for large aperture lasers, high neodymium-doped (12(DOT)1020cm-3) glasses for miniature lasers, and phosphate glasses doped with two (Yb3+, Er3+) or three (Cr3+, Yb3+, Er3+) activators have been developed in recent years. The developments were based on the systematic study of variation in glass parameters with changes in glass composition. It has been shown in carrying out the study that there are a number of diverse types of spectra for one rare earth activator, such that each type can be obtained for glasses containing different glass formers. For interpretation of rare earth glass spectra, three variants of stochastic structural models were used. High doped neodymium phosphate glasses characterized with the high value of luminescence quantum yield and excellent chemical resistance could be obtained on the basis of ultraphosphate systems.