Luminescence of borogermanate glasses activated by Er 3+ and Yb 3+ ions

Abstract

Glasses of the 25Ln 2O 3–25B 2O 3–50GeO 2 composition (mol%) where Ln = (1 − x − y) La, xEr, yYb, with an addition of Al 2O 3 have been obtained and their luminescent characteristics examined. Probabilities of spontaneous emission, peak sections of the induced radiation and quantum yields of luminescence corresponding to the 2 F 5/2 → 2 F 7/2 transition of Yb 3+ ions and the 4 I 13/2 → 4 I 15/2 transition of Er 3+ ions have been defined. Quantum yield of Yb 3+ luminescence for glasses with low Yb 2O 3 concentration reaches values closed to 100%. The luminescence spectrum of Er 3+ ions exhibits a broad peak at about 1530 nm with effective width more than 80 nm when excited by irradiation at λ = 977 nm. Spontaneous emission probability and peak stimulated radiation section for Er 3+ luminescence band 4 I 13/2 → 4 I 15/2 were determined to be equal to 175 s −1 and 4.9 × 10 −21 cm 2 respectively. Effective quenching of both rare-earth activators by oscillations with ν ≈ 2630 and 2270 cm −1 was found. These oscillators, most likely, represent OH-groups connected by a hydrogen bond with non-bridging oxygen atoms in the borogermanate matrix.