Optical Characterizations of Hot‐Pressed Erbium‐Doped Calcium Fluoride Transparent Ceramic

Nanoparticles of erbium‐doped calcium fluoride were synthesised by the coprecipitation method. Micromorphology of the obtained nanoparticles was observed by transmission electron microscopy. The nanoparticles were hot‐pressed in a vacuum environment to achieve Er : CaF 2 transparent ceramic. X‐ray diffraction analysis confirmed the crystallization of a single fluorite phase after sintered. Transmittance spectrum of Er : CaF 2 ceramic sample was measured, and the transmittance at 1200 nm reached about 87%. Microstructures were characterized using field‐emission scanning electron microscopy. The luminescence spectrum of Er : CaF 2 transparent ceramics under 488‐ and 978‐nm excitation was measured and discussed. It was evidenced that strong cross‐relaxation processes between Er 3+ ions occur at high dopant concentration, and favoring the red emission at the expense of the green one.