Examination of spectroscopic and thermographic qualities of Tm-doped and Yb/Er co-doped germanate tellurite glasses

Oxyfluride Germanate Tellurite glasses single doped with (Tm³⁺) thulium, (Tm³⁺,Yb³⁺) thulium / ytterbium co-doped and (Tm³⁺,Yb³⁺,Er³⁺) thulium / ytterbium / erbium triple-doped were fabricated. Room temperature absorption spectra were employed to evaluate the relevant radiative transition rates and branching ratio of luminescence. Distribution of the measured emission lines within UV–vis spectral region is considerably different when the selective excitation wavelengths at 358 nm and 445 nm were utilized. The excellent color purity exceeding 90 % was estimated for Tm-doped glass luminescence. The significant quantum efficiency of thulium first excited state and the related NIR emission cross section indicate potential optical amplification between 1908–2080 nm. Effective broad band tellurium optical spectra were examined employing synchrotron radiation. Ultrashort laser pulse excitations disclosed the different relaxation dynamic of the excited states and the involved interionic phenomena. Luminescence intensity ratios as function of temperature were determined for some diverse combinations of the measured bands originating in thermally coupled and non-thermally coupled levels. The highest value of relative sensitivity S_r=0.78 %K^-1 at T = 350 K was acquired for a Tm/Yb/Er co-doped glass utilizing both anti-Stokes emissions of thulium and erbium.