Optical Properties of Dysprosium‐Doped Low‐Phonon‐Energy Glasses for a Potential 1.3 μm Optical Amplifier

Dysprosium‐doped glasses were prepared in the system of gallium‐based sulfide, tellurite, zirconium‐baed and indium‐based fluorides and their optical properties were studied. From the absorption cross sections of five f‐f bands, three Judd‐Ofelt parameters, ω t ( t = 2, 4, 6), of Dy 3+ ion were determined. The compositional variaton of the ω 2 value showed the order sulfide > tellurite > fluorozirconate > fluoroindate, whereas the ω 6 value showed the opposite tendency. Compositional variaton of the fluorescence intensity ratio of the ( 4 F 9/2 6 H 13/2 )/( 4 F 9/2 )→ 6 H 15/2 ) is explained by the ratio of ω 2 /ω 6 of doped Dy 3+ . The emission probabilities A and the branching ratio β from 6 H 9/2 and 6 F 11/2 levels, which are the doublet initial level of the 1.3 μm luminescence, were calculated for the glasses, and it was found that both values showed a tendency similar to that of ω 2 against the glass composition. In the sulfide glass, A was 2.6 × 10 3 S ‐1 and β was 93%, both the highest in all of the glasses investigated. By 1.06 μm pumping of a Nd: YAG laser, the sulfide glass showed strong 1.3 μm emission and the lifetime was 25 μs, resulting in a quantum efficiency of 7%. This value is higher than that of the Pr 3+ : 1 G 4 level in ZBLAN glass with β= 60%.