On the excitation mechanisms of the infrared-excited visible luminescence in Yb3+, Er3+-doped fluorides

Lattices doped with Yb3+ and Er3+ can be excited by infrared radiation (970 nm) to give green and red emission. Information upon the excitation mechanisms of the infrared-excited visible luminescence is obtained from the emission spectra under 365 nm and under 970 nm excitation and from the excitation spectra of the green and red emission in the excitation region between 350 nm and 500 nm. This is demonstrated for a number of Yb3+, Er3+-doped fluorides showing a high infrared-to-visible conversion efficiency.