Based on the rate equations under the steady-state condition, strongly backward-pumped Yb(3+)-doped double-clad fiber (YDCF) lasers are analyzed numerically. The effects of laser cavity feedbacks and length of YDCF on the laser performance and the dependency of the output laser power on the pump power are investigated. Using a 975 nm laser diode (LD) as the pump source, a backward-pumped YDCF laser with a slope efficiency of 82% is demonstrated experimentally. The output laser power at the wavelength of 1088 nm is up to 85 W. The experimental results are in good agreement with those by numerical simulations
