Preparation, structure and properties of Yb3+FP laser glass

Conditions for preparing samples of Yb3+-doped fluoroaluminate glasses of high optical quality (Deltan less than or equal to 2x10(-6)), their structure, and optical properties have been studied while varying the phosphate (5 to 40 mol%) and the Yb3+ content (5 to 12 x 10(20) ions/cm(3)). Refractive index and dispersion increase the higher the phosphate content. Adding Nb2O5 to the glass composition or substituting phosphate by sulfate increases the non-linear refractive index, due to an enhanced asymmetry of the Yb3+ sites resulting in larger cross sections for absorption and emission. Depending on melt composition the fluorescence lifetime of the F-2(5/2) laser level drops from 2.0 and 1.1 ms when phosphate content is increased but it shows no concentration quenching at higher Yb3+-doping levels. Glasses exhibit a very low OH content with an absorption of less than 0.1 cm(-1) at around 3000 cm(-1).