 As an even @-@ numbered lanthanide , in accordance with the Oddo @-@ Harkins rule , ytterbium is significantly more abundant than its immediate neighbors , thulium and lutetium , which occur in the same concentrate at levels of about 0 @.@ 5 % each . The world production of ytterbium is only about 50 tonnes per year , reflecting the fact that ytterbium has few commercial applications . Microscopic traces of ytterbium are used as a dopant in the Yb : YAG laser , a solid @-@ state laser in which ytterbium is the element that undergoes stimulated emission of electromagnetic radiation . 
