Distribution of Yb3+ and Yb2+ Ions along YbF3-Doped BaF2 Crystals

Abstract

BaF2 crystals doped with 0.05, 0.1, and 0.2 mol% YbF3 are grown using vertical Bridgman method. Transparent crystals, ≈5–6 cm in length, ≈10 mm in diameter, are obtained in vacuum using a shaped graphite furnace. The absorption spectra reveal the characteristic absorption bands of the Yb3+and Yb2+ ions in the as-grown crystals. The distribution of ytterbium ions along the crystals and the effective segregation coefficient of the Yb3+ and Yb2+ ions in the BaF2 host are determined by using the optical absorption method. The crystals are cleaved from the bottom to the top into 10–17 slices of ≈2 mm thickness. The optical absorption spectrum of every slice is recorded. The dopant distribution along the crystal is estimated studying the absorption spectrum of every slice. Two well-shaped and strong characteristic bands, 968 nm and 352 nm, respectively, are chosen. The Yb3+ and Yb2+ ions are not uniformly distributed along the BaF2 crystals. The calculated effective segregation coefficients of the Yb3+ range from 0.7 to 0.84 and from 0.66 to 0.82 for Yb2+ ions.