Spectroscopic characteristics of Eu-doped aluminosilicate optical fiber preform

An optical fiber whose core is an aluminosilicate glass doped with Eu⁺² and Eu⁺³ have been made using modified chemical vapor deposition (MCVD) and a novel aerosol delivery technique developed at Brown University. The UV-visible absorption of the preform has been studied in 200 - 700 nm range as well as the excitation and emission spectra between 250 and 720 nm. Three broad UV absorption bands with maxima at 255, 302, and 316 nm have been observed. The 302 nm band is attributed to the energy transfer from Eu⁺² to Eu⁺³, while the 255 and 316 nm bands are correlated with the 4f⁷→4f⁶5d¹(t_2g) and 4f⁷→4f⁶5d¹(e _g) transition of Eu⁺². For Eu⁺² emission, a linear relation between excitation and maximum emission wavelength has been observed as the excitation wavelength increases beyond 375 nm.