The effects of Yb 3‡ ion concentration on physical, optical, and spectroscopic properties have been studied in a low phonon (∼590 cm −1) barium-lanthanum-tellurite glass. Due to the unfeasibility of Judd-Ofelt theory Yb 3‡ -doped systems, the oscillator strength of absorption transition, 2 F 7∕2 → 2 F 5∕2 has been evaluated by using the Smakula equation. The nature of emission from 2 F 5∕2 → 2 F 7∕2 transition of Yb 3‡ ions is described theoretically by using a rate equation in comparison with experimental results. By applying reciprocity (RM) and Fuchtbauer-Ladenburg meth-ods on emission spectra as well as the excitation random walk model on measured fluorescence lifetimes, the radiation trapping and concentration quenching effects have been discussed. Considering all the spectroscopic and laser performance parameters, an optimum Yb-ion doping concentration (YT1) has been determined, and the gain measurements performed on the sample revealed a flat gain over a broad wavelength range could be achieved even with a low (∼20%) excitation population density. A comparative study with other hosts revealed the potenti-ality of the present glass for ∼1 micron emission.