Local structure and its effect on the oscillator strengths and emission properties of Ho3+ in chalcohalide glasses

The formation of structural units in Ge–Ga–S glass with CsBr addition and its effect on the optical band gap and several spectroscopic properties of Ho3+ were investigated. The optical band gap of the host glasses and the oscillator strengths of Ho3+ absorption decreased sharply when the ratio of CsBr/Ga became close to unity. These property changes were associated with the formation of structural units of [GaS3/2Br]− and they have a crucial effect on the changes of the local structure around Ho3+ ions. The local structure was not sensitive to the As or Br addition but was critically dependent on the concentration of CsBr.