Optical properties of manganese in barium phosphate glasses

Spectroscopic studies of optical properties of manganese ions in barium phosphate glasses prepared by adding 1–20 mol% of Mn2O3 in the glass composition were performed. Depending on the processing conditions, both Mn2+ and Mn3+ species were present, as indicated by the absorption spectra. However, emission and excitation spectra measurements showed the existence of only one luminescent center, even at cryogenic temperatures, ascribed to Mn2+. Although the measured luminescence decay time curves were non-exponential, a comparison of different samples indicated that two distinct luminescence effects are involved. Exchange interaction between Mn2+ ions is responsible for the emission red shift associated with the manganese concentration increase. Moreover, the luminescence decay time indicates that a non-radiative energy transfer is also involved in the deexcitation process.