Chromium-ytterbium energy transfer in silicate glass

Abstract

Energy transfer has been observed between trivalent chromium and ytterbium ions in a silicate glass. Optical absorption and emission spectra of Cr³⁺ and Yb³⁺ are presented and show that the chromium emission, which occurs as a broad‐band fluorescence in the near‐infrared, overlaps the ytterbium absorption. Hence Cr³⁺ ions can be used to sensitize YB³⁺ fluorescence. Cr³⁺‐to‐Yb³⁺ energy transfer was established from the Yb³⁺ fluorescence excitation spectrum and the decrease in the Cr³⁺ fluorescence intensity and lifetime. A decrease in the Yb³⁺ lifetime with increasing Cr³⁺ content was also observed indicating relaxation of Yb³⁺ by back transfer to the faster relaxing Cr³⁺ ions. Measurements of the Yb³⁺ and Cr³⁺ fluorescence lifetimes as a function of temperature and chromium content are reported.