Optical properties of dysprosium-doped low-phonon-energy glasses for a potential 1.3 mu m optical amplifier

Dysprosium-doped glasses were prepared in the system of gallium-based sulfide, tellurite, zirconium-based and indium-based fluorides and their optical properties were studied. From the absorption cross sections of five f-f bands, three Judd-Ofelt parameters, Omega //t (t equals 2, 4, 6), of Dy**3** plus ion were determined. The compositional variation of the Omega //2 value showed the order sulfide greater than tellurite greater than fluorozirconate greater than fluoroindate, whereas the Omega //6 value showed the opposite tendency. Compositional variation of the fluorescence intensity ratio of the (**4F//9/////2 yields **6Hi//1//3/////2)/(**4F//9/////2 yields **6H//1//5///// //2) is explained by the ratio of Omega //2/ Omega //6 of doped Dy**3** plus . The emission probabilities A and the branching ratio beta from **6H//9/////2 and **6F//1//1/////2 levels, which are the doublet initial level of the 1.3 mu m luminescence, were calculated for the glasses, and it was found that both values showed a tendency similar to that of Omega //2 against the glass composition. In the sulfide glass, A was 2.6 multiplied by 10**3 s** minus **1 and beta was 93%, both the highest in all of the glasses investigated. By 1.06 mu m pumping of a Nd:YAG laser, the sulfide glass showed strong 1.3 mu m emission and the lifetime was 25 mu s, resulting in a quantum efficiency of 7%. This value is higher than that of the Pr**3** plus :**1G//4 level in ZBLAN glass with beta equals 60%. (Author abstract) 16 Refs.

Tanabe, Setsuhisa Hanada, Teiichi Watanabe, Masayuki Hayashi, Tetsusuke Soga, Naohiro