Optical spectroscopy of Yb2+ ions in YbF3-doped CaF2 crystals

Abstract Transparent colorless Ca 1− x Yb x F 2+ x ( x =0.0007–0.016) crystals were grown using the vertical Bridgman technique. In order to obtain efficient Yb 3+ –Yb 2+ conversion in the as-grown crystals, a special procedure has been developed. Room temperature optical absorption spectra reveal the characteristic UV absorption bands of the Yb 2+ ions in the as-grown crystals, with intensities more than 10 times higher than those reported by other authors using various conversion procedures. The influence of YbF 3 content and of codoping with Pb 2+ ions on the absorption and emission spectra has been studied. Room temperature emission bands in the near UV (not reported before) and in the visible spectral domain have been observed. The emission intensity depends on the dopant concentration. A comparison of our results with those obtained by other authors is also given.