Effect of CsBr addition on the emission properties of TM3+ ion in Ge-Ga-S glass

Abstract

Absorption and emission properties of Tm3+ in (1-x) (Ge0.25Ga0.10S0.65)-xCsBr glass (x = 0.00-0.12) were investigated. Upon 10 mol % CsBr addition, the absorption cross sections of Tm3+ decreased accompanied by a large increase in the lifetime of the Tm3+:(3) H-4 level to 1.23 ms since Tm3+ ions were surrounded by the Br ions of [GaS3/2Br](-) units. As the concentration of Tm3+ increased, the H-3(4) level lifetime decreased due to cross relaxation (Tm3+:H-3(4),H-3(6)-->Tm3+:(3) F-4, F-3(4)). Temperature dependence of the H-3(4) level lifetime showed that cross relaxation in Tm3+ is a phonon-assisted energy transfer process. When Tm3+ were surrounded by Br ions, cross relaxation among Tm3+ was also suppressed clue to a decrease in the transition probability among Tm3+ energy levels, a decrease in phonon energy of the host glasses, as well as an increase in the number of phonons participating in the cross relaxation process. The potential of Tm3+-doped Ge-Ga-S-CsBr glasses for S-band fiber amplifiers is also discussed.