THE EFFECT OF COMPOSITIONAL VARIATIONS ON THE PROPERTIES OF RARE-EARTH-DOPED GE-S-I CHALCOHALIDE GLASSES

Undoped and Pr3+-doped GexSyIz glasses, with atomic concentrations of germanium 0.33 less than or equal to x less than or equal to 0.43 and iodine 0 less than or equal to z less than or equal to 20, respectivel y, were synthesized and their optical and thermal properties measured. These properties followed the same compositional trends as the binary GexS1-x glasses, for which 0.33 less than or equal to x less than or equal to 0.43. The compositional dependences of the absorption edge an d rare-earth solubility in GexSyIz glasses can be presented with a sin gle parameter p = (y + z/2)/x. Addition of iodine to the Ge-rich GexS1 -x-base glass system resulted in increasing the optical bandgap energy and decreasing the glass transition temperature. Thermal stability of the GexSyIz glasses is a function of both S/Ge ratio and iodine conce ntration. XPS and Raman spectroscopic measurements were conducted to o btain information about the structural changes accompanying the compos itional variations. Properties-structure correlations are discussed. T he results of the present study were used for selection of a compositi onal range within the GexSyIz glass system with optimal properties req uired for Pr3+-doped fiber amplifier application. (C) 1997 Elsevier Sc ience B.V.