Effect of lithium-potassium mixed alkali on spectroscopic properties of Er³⁺-doped aluminophosphate glasses

Er^3+-doped lithium-potassium mixed alkali aluminophosphate glasses belonging to the oxide system xK_2O-(15-x)Li_2O-4B_2O_3-11Al_2O_3-5BaO-65P_2O_5 are obtained in a semi-continuous melting quenching process. Spectroscopic properties of Er^3+-doped glass matrix have been analysed by fitting the experimental data with the standard Judd--Ofelt theory. It is observed that Judd--Ofelt intensity parameters \it\Omega_ t (t= 2, 4 and 6) of Er^3+ change when the second alkali is introduced into glass matrix. The variation of line strength S_\rm ed^4I_13/2,^4I_15/2 follows the same trend as that of the \it\Omega_6 parameter. The effect of mixed alkali on the spectroscopic properties of the aluminophosphate glasses, such as absorption cross-section, stimulated emission cross-section, spontaneous emission probability, branching ratio and the radiative lifetime, has also been investigated in this paper.