Raman spectroscopy of rare earth doped silver halide crystals

The phonon energy of rare earth doped silver halide crystals was investigated using Raman spectroscopy. An additional phonon vibrational mode was observed and attributed to localized defect vibrational modes. Good agreement was found between the measured and the predicted frequencies of the local modes. These additional low energy (65-80 cm-1) vibrational modes do not increase the thermal quenching of mid-IR luminescence of the rare earth ions in silver halide crystals. The rare earth doped silver halide crystals are suitable for the fabrication of mid-IR solid state lasers and fiber lasers due to their extremely low phonon energies.