Tandem pumping structure is one of the approaches to enable every single fiber of a laser to reach the maximum output power limit.This paper carries out the research work on tandem pumping-structured lasers.It first establishes a simplified model for numerical simulation

determining that the optimal pumping wavelength of such lasers should be in the range of1 010

1

030 nm.Then

it develops a highly efficient 1 018 nm fiber

conducts laser performance tests and carries out comparisons

analysis and discussions.The results show that co-doping causes sub-peak of the Yb3+ionic emission blue shift

promoting the output of the 1 018 nm laser and that increasing the core/cladding ratio is conducive to improving the 1 018 nm laser output efficiency.