Effect of OH― Content on Mid―infrared Emission Properties in Er3+―doped Ge―Ga―S―CsI Glasses

A series of Er3+―doped chalcogenide glasses based on Ge―Ga―S―CsI system were prepared by melt―quenching technique with distillation processing. Properties including refractive index, infrared transmission spectra, 2.85um mid―infrared emission spectra and fluorescence lifetime under 800 nm laser excitation were measured. The infrared absorption coefficients of OH― groups at 3um according to the infrared transmission spectra were calculated, and the constant KOH―Er, determined by the strength of interactions between Er3+ ions and OH― groups in the case of energy transfer was also calculated. The effect of hydroxyl content on mid―infrared emission properties of glass samples was discussed. The results show that the remnants OH― content of glass samples can be effectively reduced by the distillation processing. The 2.85um mid―infrared fluorescence emission intensity and fluorescence lifetime of Er3+ ions are also enhanced. The calculated constant KOH―Er is about 1.08×10―16cm4/s. Because of the efficiency of energy transfer between Er3+ ions and OH― groups, the remnants of a small amount of OH― groups can still directly affect the intensity of 2.85um fluorescence.