Optimizing the mode-to-pump ratio in end-pumped quasi-three-level Nd-doped lasers considering the energy-transfer upconversion

The reabsorption losses considering energy-transfer-upconversion effects and the losses due to energy-transfer upconversion are derived as a function of the mode-to-pump ratio and the output coupler transmission in end-pumped quasi-three-level Nd-doped lasers, respectively. The dependence of thermally induced diffraction losses on the mode-to-pump ratio and the output coupler transmission is investigated with the energy-transfer-upconversion effects considered. The mode-to-pump ratio with and without thermally induced diffraction losses considering the energy-transfer upconversion is optimized. The results show that the optimum mode-to-pump ratio with the upconversion effects is less than that in which the energy-transfer-upconversion effects are neglected.