 In order to achieve even higher power levels in ytterbium @-@ based fiber systems all factors of the fiber must be considered . These can only be achieved via optimization of all the ytterbium fiber parameters , ranging from the core background losses to the geometrical properties , in order to reduce the splice losses within the cavity . Power scaling also requires optimization of matching passive fibers within the optical cavity . The optimization of the ytterbium @-@ doped glass itself through host glass modification of various dopants also plays a large part in reducing the background loss of the glass , improvements in slope efficiency of the fiber and improved photodarkening performance . All of which contribute to increased power levels in 1 µm systems . 
