Fluorescence features of Tm³⁺-doped multicomponent borosilicate and borotellurite glasses for blue laser and S-band optical amplifier applications

Novel B₂O₃–SiO₂–Al₂O₃–ZnO–Li₂O/MgO and B₂O₃–TeO₂–PbO–ZnO–Li₂O–Na₂O glasses with different concentrations of Tm₂O₃ were synthesized by using the melt-quench method. All the fabricated samples have been characterized by visible emission spectra and decay times, including near-infrared (NIR) luminescence measurements. For 0.5 mol% Tm³⁺-doped borotellurite glass, several radiative parameters are evaluated using the Judd-Ofelt parameters. The intensity of all the visible emission bands increased with the increase of Tm₂O₃ concentration up to 0.5 mol%, and beyond this doping content, luminescence concentration quenching takes place. The luminescence intensity quenching is attributed to energy transfer (ET) processes through cross-relaxation (CR) channels. The visible luminescence decay curves were well fit with a single exponential (for Tm³⁺: ¹D₂ level) and double exponential (for Tm³⁺: ¹G₄ level) functions for the multicomponent borosilicate samples, while Inokuti-Hirayama model was used for the multicomponent borotellurite glass ¹D₂ level decay time fit. The derived decay lifetimes of the ¹D₂ level are found to be much shorter than that of the ¹G₄ level. In Li₂O (alkali) or MgO (alkaline) containing borosilicate samples, pumped under 808 nm laser diode, the ³H₄→³F₄ (1.458 μm) emission intensity increased from 0.1 to 2.0 mol% Tm³⁺ ion concentration, indicating negligible CR processes. The computed Full-Width at Half-Maximum (FWHM) values for the 1458 nm emission in 2.0 mol% Tm³⁺-doped Li and Mg series borosilicate samples are 117 and 125 nm, respectively, while the FWHM value for 0.5 mol% Tm₂O₃ content doped borotellurite glass is 118 nm. Following the analyzed visible and NIR optical results, the fabricated Tm³⁺ glasses could be useful for blue laser and S-band optical amplifier applications.