Infrared-to-visible conversion in (Y, Yb, Er)F3 and (Y, Yb, Ho)F3

Abstract

Visible emission spectra from (Y0.80Yb0.19Er0.01)F3 and (Y0.80Yb0.19Ho0.01)F3 were obtained upon excitation at 970 nm. Emission bands at 656, 548, 520, 409, and 380 nm are observed in the Er3+phosphor, and at 746, 645, 544, and 489 nm in the Ho3+phosphor. The origin of each of these bands is discussed. Data presented for the 656 nm emission in the Er3+phosphor show that it can be the result of only one of three previously proposed mechanisms. The 746 nm band from the Ho3+ system has not been previously discussed in the literature even though it is the most intense emission band. Data presented for the temperature dependence of the upconversion process in these two phosphors show that generalizatons made about the mechanism of energy transfer in the Ho3+ system based on the more widely studied Er3+ system are not valid.