Optical spectroscopy and energy transfer in Tm^3^+-doped metaphosphate laser glasses

TLDR: In this paper, the authors measured the phonon sideband spectrum for 1.0 mol% Eu 3+ -doped metaphosphate glass of the same composition and compared with the Raman spectrum.

Abstract: Thulium-doped metaphosphate glasses with four concentrations (0.01, 0.1, 1.0 and 2.0 mol%) of Tm 3+ have been prepared and investigated by Raman, absorption and photoluminescence spectral studies. The phonon sideband spectrum has been measured for 1.0 mol% Eu 3+ -doped metaphosphate glass of the same composition and compared with the Raman spectrum. From vibronic spectra, various bands associated with different structural groups have been identified and assigned. Absorption band positions have been used to simulate the complete energ yl evel diagram for the Tm 3+ ion using the model Hamiltonian. Judd–Ofelt parameters have been determined from the absorption bands .U sing these parameters, transition probabilities, excited state lifetimes and transition branching ratios have been evaluated. The emission and decay curves of the 1 D2 level have been measured for all four glass samples both at RT and 15 K. Lifetimes show a strong quenching for Tm 3+ concentrations higher than 0.1 mol%. Fluorescence decay curves of the 1 D2 level have been well fitted to th eI nokuti–Hirayama model for S = 6, suggesting that the mechanism for energy transfer between Tm 3+ ions is of dipole–dipole type.