Excitation energy transfer between Pr$^{3+}$ and Nd$^{3+}$ rare-earth ions in silicate glass

Nonradiative excitation transfer (NET) was observed between trivalent Pr$^{3+}$ and Nd$^{3+}$ ions in silicate glass. Cooperative sensitisation of the luminescence of Nd$^{3+}$ ions by Pr$^{3+}$ ions in the ${}^{4}F_{3/2} \to {}^{4}I_{13/2}$ transition was observed as a result of NET. The luminescence was excited by the cw radiation of an Nd$^{3+}$:YAG laser with a power of $\sim$800 mW ( $\lambda$ = 1.064 $\mu$m) operating on the basis of the ${}^{3}H_4 \to {}^{1}G_4$ transition at the wavelength corresponding to the Pr$^{3+}$ absorption band. The NET mechanism, responsible for the luminescence of the Nd$^{3+}$ ion at the wavelength corresponding to the band with a maximum at $\lambda$ = 1.34 $\mu$m, is discussed.