Optical and radiative properties of Sm3+ions activated alkali-bismuth-germanate glasses

Trivalent samarium (Sm3+)-doped alkali-bismuth-germanate glasses of a composition (40-x) GeO2 + 20 Bi2O3 + 20 Na2O + 10 BaO + 10 Gd2O3 + x Sm2O3 (x = 0.05, 0.1, 0.5, 1.0, 1.5 and 2.5 mol%) (GeBiNaBaGdSm) were made from a typical melt-quenching procedure. An optical absorption, photoluminescence excitation, emission and decay curves of GeBiNaBaGdSm glasses were studied. For the 4G5/2 → 6H7/2 transition, an intense orange emission at 601 nm was observed when the Sm3+ ions pumped by 405 nm. A high value of 15.59×10−22 cm2 stimulated emission cross-section and 20.59×10−28 cm3 of optical gain bandwidth for the 1.5 mo% Sm2O3-doped GeBiNaBaGdSm15 glass were obtained. The experimental lifetime (τexp) was increased up to GeBiNaBaGdSm05 glass, thereafter diminished with further increase of Sm3+ ion concentration. Decay profiles of Sm3+ ions were fitted using I-H model. Energy transfer rate (WET) for GeBiNaBaGdSm10 glass is evaluated to be 554 s−1. The average red to orange (R/O) intensity ratio of these glasses is found to be 0.123. Furthermore, CIE chromaticity coordinates demonstrate that the emission was observed in the orange region and then shifted to red region with the increase of Sm3+ ion concentration. All the studies revealed that these glasses could be useful for tunable color display applications.