Erbium(III) iodide serves as a source of erbium ions in the synthesis of specialized optical materials and laser technologies, leveraging the luminescent properties of Er³⁺ in the near-infrared range. It is commonly used to prepare erbium-doped glass or crystal matrices for optical amplification in fiber optics, particularly in C-band and L-band communication systems. Additionally, it supports research into solid-state lasers, upconversion materials for bioimaging and photonic devices, and high-purity applications in quantum memory and photonic integrated circuits.