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

摘要

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 ~2F_(5/2) → ~2F_(7/2) transition of Yb~(3+) ions and the ~4I_(13/2) → ~4I_(15/2) transition of Er~(3+) ions have been defined. Quantum yield of Yb_3+ luminescence for glasses with low Yb2O3 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 ~4I_(13/2) → ~4I _(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.