Used as a dopant in optical fibers and laser materials, particularly in high-power and high-efficiency solid-state lasers. Enhances performance in fiber amplifiers and is utilized in telecommunications for signal boosting. Plays a role in the production of specialty glasses with high refractive indices and improved durability. Applied in thermal barrier coatings due to its stability at high temperatures. Investigated for use in advanced battery materials and as a catalyst in certain organic reactions. Also employed in scientific research involving quantum memory and photonic devices.