A series of lead free fluoro-tellurite glasses containing different concentration of Er 2 O 3 were prepared and the optical properties of the best luminescent sample (1 g mol% of Er 2 O 3 ) have been investigated by Judd-Ofelt theory to judge its suitability as practical photonic material. Three intensity parameters X 2 = 4.935 Â 10 À20 cm 2 , X 4 = 3.148 Â 10 À20 cm 2 , X 6 = 1.745 Â 10 À20 cm 2 of the ion in the glass, were determined from the optical absorption data, which were used to calculate the parameters like the radiative transition probabilities (A r ), radiative life-times (s f ), fluorescence branching ratios (b c ) and the integrated emission cross-section (Rr) of its different transitions. Experimental optical absorption intensity and the calculated values of oscillator strength (P), suggested that the Er +3 ions in the glass can most effectively be excited by 4 I 15/2 ? 4 G 11/2 (376 nm), 4 I 15/2 ? 4 F 7/2 (486 nm) and 4 I 15/2 ? 2 H 11/2 (519 nm) transitions while calculated spontaneous emission rate (A r ) values showed that strong visible emissions at 650 nm and 546 nm should occur, respectively, through ( 4 F 9/2 ? 4 I 15/2 ) and ( 4 S 3/2 ? 4 I 15/2 ) transitions and NIR emissions at 1532, 1222, 974 and 838 nm, respectively, through ( 4 I 13/2 ? 4 I 15/2 ), ( 4 S 3/2 ? 4 I 11/2 ), ( 4 I 11/2 ? 4 I 15/2 ), and ( 4 S 3/2 ? 4 I 13/2 ) transitions. The spectroscopic data indicate that the present glass is a prospective photonic material for practical applications in the visible and NIR region.