Low phonon concentration lasing glasses for 1.3 µm amplification

Abstract

Ge-Ga-S-glasses doped with 15000 mole-ppm Pr3+ have been developed for applications in optical amplifiers for 1.3 ìm. The formation of crystalline phase separations in Ge25Ga10S65 could be suppressed by modification of the glass composition with Sb. Samples have been prepared by melting in sealed silica ampoules at 950°C. Ge-Ga-Sb-S-glasses, doped with 15000 mole ppm Pr3+, were synthesized by addition of Sb2S3 up to contents of 14.3 mole% to the composition Ge25Ga10S65 (corresponding to 83,3GeS2-16,7Ga2S3) or by replacing up to 50 mole% of Ga by Sb. Transparent to opaque glasses were obtained which were free from crystalline phase separations. The modification of the glasses with Sb leads to a remarkable decrease of the transformation temperature of the glasses. However, the temperature working range remains almost unaffected. The transparent glasses exhibit with 15 - 18 µs the same fluorescence lifetimes and the same fluorescence maximum position (1340 - 1341 nm) and FWHM (63 nm) as the unmodified Ge-Ga-S-glass. The preparation process for both glass systems could be optimized to obtain monoliths with lengths of several centimeters and intrinsic optical losses of only 0.05 dB/cm at 1.3 µm (after correction of reflection), which is of very high importance for the future development of planar amplifiers with remarkable net gain.