Broadband fluorescence emission of Eu3+ doped germanotellurite glasses for fiber-based irradiation light sources

Eu3+ doped fiber-based germanotellurite (NZPGT) glasses with medium-low maximum phonon energy of 782 cm(-1) have been fabricated and characterized. Judd-Ofelt intensity parameters Omega(2) (6.25 x 10(-20) cm(2)) and Omega(4) (1.77 x 10(-20) cm(2)) indicate a high asymmetrical and covalent environment around Eu3+ in the optical glasses. The spontaneous emission probability of the dominant transition D-5(0) -> F-7(2) peaking at 612.5 nm and the corresponding maximum stimulated emission cross-section were derived to be 445.7 s(-1) and 2.05 x 10(-21) cm(2), respectively, confirming the effectiveness of the red fluorescence emission. The quantum yield was derived to be 12% under 391 nm LED excitation, and approximately 88% photons have been demonstrated in wavelength range of 600-720 nm, indicating that Eu3+ doped NZPGT glasses under proper excitation conditions are promising optical materials for fiber-based irradiation light sources that are competent to activate diverse photodynamic therapy photosensitizers. (C) 2013 Optical Society of America