Effect of Fluorine Ions on 2.7 μm Emission in Er3+/Nd3+-Codoped Fluorotellurite Glass

The 2.7 mu m emission properties of Er3+/Nd3+-codoped fluorotellurite glasses were investigated in the present work. The thermal stability, refractive index, absorption and transmission spectra, and emission spectra were measured and investigated. The 2.7 mu m emission in Er3+/Nd3+-codoped fluorotellurite glasses was enhanced with the increase of fluorine ions. The Judd-Ofelt analysis based on absorption spectra was performed in order to determine the Judd-Ofelt intensity parameters Omega t (t = 2, 4, 6), spontaneous emission probability, radiative lifetime and branching ratios of Er3+:I-4(11/2) -> I-4(13/2) transition. It is found that the Er3+/Nd3+-codoped fluorotellurite glass possesses a lower spontaneous transition probability A (58.95 s(-1)) but a higher branching ratio beta (15.72%) corresponding to the stimulated emission of Er3+:I-4(11/2) -> I-4(13/2) transition. Additionally, the transmittance was also tested and reached a maximum when the molar concentration of ZnF2 is 15%. The presence of fluorine ions greatly decreases the population of OH- groups, which affects the 2.7 mu m emission effectively by means of decreasing the rate of energy transfer to impurities (e.g., OH- groups).