Energy transfer mechanism in Er3+ doped fluoride glass sensitized by Tm3+ or Ho3

Enhanced 2.7 \mu m emission is obtained in Er3+/Tm3+ and Er3+/Ho3+ codoped ZBYA glasses. Absorption and emission spectra are tested to characterize the 2.7 \mu m emission properties of Er3+/Tm3+ and Er3+/Ho3+ doped ZBYA glasses and a reasonable energy transfer mechanism of 2.7 \mu m emission between