Optical absorption and fluorescence properties of $Er^{3+}$ in sodium borate glass

Spectroscopic properties of $Er^{3+}$ ions in sodium borate glass have been studied. The indirect and direct optical band gaps $(E_{opt})$ and energy level parameters (Racah $(E^{1}, E^{2} and E^{3})$, spin-orbit $(\xi_{4f})$ and configurational interaction (\alpha)) are evaluated. Spectral intensities for various absorption bands of $Er^{3+}$ doped sodium borate glass are calculated. Using Judd-Ofelt intensity parameters $(\Omega_{2},\Omega_{4}, \Omega_{6})$, radiative transition probabilities (A), branching ratios (\beta) and integrated absorption cross sections (\Sigma) are reported for certain transitions. The radiative life times $(\tau_{R})$ for different excited states are estimated. From the fluorescence spectra,the emission cross section $(\sigma_{p})$ for the transition, $^{4}I_{13/2} -> ^{4}I_{15/2}$ is reported.