Photonic Applications of Rare-Earth-Doped Materials

摘要

The elements of the lanthanide series, from Ce (atomic number 58) to Yb (atomic number 70), form a group of chemically similar elements that have in common a partially filled 4f shell. These so -called "rare earth" (RE) elements usually take on a 3+ ionic state (RE) elements usually take on a 3+ ionic state (RE~3+). Because the 4f electronic-energy levels of each lantha- nide ion are shielded from external fields by 5s~2 and 5p~6 outer-shell electrons, RE~3+ energy levels are predominantly inde- pendent of their surroundings.