White emission of Yb 2+ :fluoride glasses efficiently excited with near-UV light

Various Yb2+-containing fluoride glasses melting under a reductive atmosphere were prepared. The brightest white light emission was observed for an AlF3-based fluoride glass not containing Hf or Zr. The largest full width at half maximum of the white emission spectra was 202 nm. In addition, incorporation of chloride into the AlF3-based glass enabled efficient excitation with near-ultraviolet light corresponding to a GaN bandgap of 3.4 eV and the maximum internal quantum efficiency of Yb2+: AlF3-based fluoride glass was 42%.