Influence of Nd3+ concentration on its optical absorption and luminescence properties in potassium borate glass

Spectroscopic and laser properties of Nd3þ doped potassium borate glass have been studied for different Nd3þ concentrations ranging from 0.5 to 2.0 mol%. From the absorption spectra, optical band gaps (Eopt) and various spectroscopic parameters (E1, E2, E3, \xi4f and \alpha) are determined. Using Judd-Ofelt intensity parameters \Omega2, \Omega4 and \Omega6, radiative lifetimes (\tau R), branching ratios (\beta) and integrated absorption cross sections (\Sigma) have been calculated for certain excited states of Nd3+ for all the Nd3+ concentrations. From the spectral profiles of the hypersensitive transition, it is observed that there is slight change in the environment of Nd3+ ion in different concentrations of Nd3+ doped potassium borate glass. The radiative lifetimes (\tau R) for certain excited levels are minimum when the concentration is high. From the emission spectra, peak wavelengths (\lambda p), effective line widths (\Delta\lambda eff) and stimulated emission cross-sections (\sigma p) have been obtained for the three transitions 4F3/2 \rightarrow 4I9/2, 4F3/2 \rightarrow 4I11/2 and 4F3/2 \rightarrow 4I13/2 of Nd3+ and are compared for different concentrations