Sol-gel synthesis of rare-earth-doped lanthanum halides for highly efficient 1.3-μm optical amplification

Praseodymium- and dysprosium-doped lanthanum halide powders have been synthesized by a sol-gel-reactive-atmosphere approach. Emission at 1.3 μm from a sol-gel-derived material was observed for the first time to our knowledge. Measured lifetimes corresponded to radiative quantum efficiencies of approximately 8% for Pr³⁺:LaF₃, 72% for Pr³⁺:LaCl₃, and 78% for Dy³⁺:LaCl₃. The spectroscopic properties of these hosts are shown to be comparable with those of melt-grown single-crystal analogs, verifying the ability of inexpensive and low-temperature solution-based methodologies to produce low-phonon-energy materials.