Erbium (Er) is a chemical element that has atomic number 68 in the periodic table of elements. It belongs to the rare earth metals.
Erbium is used in optical amplifiers such as the EDFA amplifier with erbium-doped optical fibers and for dopingresonators in solid-state lasers.
In components for optical data transmission and lightwave generation, erbium is used in combination with silicate and phosphate glasses. The emission wavelengths of erbium are 0.55 µm, m and 2.7 µm.