∼2 μm broadband luminescence in Tm3+/Ho3+/Er3+-doped tellurite glass

Abstract

Improving the broadband luminescent properties in ∼2 μm band has always been a serious challenge. This paper proposed a Tm³⁺, Ho³⁺ and Er³⁺ doped combination in tellurite glass, which was synthesized through melt-quenching and characterized by a series of physical and spectral tests. Firstly, tellurite glass of Tm³⁺–Ho³⁺ co-doping produced a ∼2 μm broadband luminescence ranging from 1570 to 2200 nm with FWHM (full width at half maximum) of 379 nm under 808 nm pumping. This broadband luminescence originated from ³F₄ to ³H₆ level transition of Tm³⁺ and ⁵I₇ to ⁵I₈ level transition of Ho³⁺. Furthermore, after adding an appropriate amount of Er³⁺, the luminescent intensity was improved by 116 %, mainly attributed to the direct or indirect energy transfers from Er³⁺ to Tm³⁺ and Ho³⁺ ions. Calculations of Judd-Ofelt spectroscopic parameters and gain cross-sections supported the results obtained from Tm³⁺/Ho³⁺/Er³⁺ doped tellurite glass in ∼2 μm band. In addition, DSC (differential scanning calorimetry) curves exhibited excellent thermal stability, XRD (X-ray diffraction) patterns and Raman spectra disclosed the non-crystalline and network structural units of the synthesized tellurite glasses. The findings in this work demonstrate that tellurite glass with Tm³⁺, Ho³⁺ and Er³⁺ combination is an efficient strategy which can be applied in ∼2 μm band ultra-short pulse lasers and broadband amplifiers.