Used in the production of specialty optical fibers and laser materials due to its ability to enhance performance in infrared optics. Commonly doped into fiber lasers and amplifiers for telecommunications and high-power industrial laser systems. Serves as a component in upconversion phosphors for display technologies and solid-state lasers. Applied in research and development of advanced ceramic materials and electronic components. Also utilized in thin-film coatings for optical devices requiring durability and precise refractive index control.