Impact of energy-transfer-upconversion on the performance of hybrid Er:YAG lasers

Abstract

Using a hybrid fiber-bulk laser scheme based on Er:YAG, we have achieved ~60 W and ~30 W of continuous-wave output at 1645nm and 1617nm respectively, and Q-switched pulse energies up to ~30 mJ (limited by coating damage). Investigation of various factors influencing laser performance has revealed that energy-transfer-upconversion can have a very detrimental impact on efficiency, even in continuous-wave mode of operation. In this paper we report on the results of this study, discuss various measures for reducing energy-transfer-upconversion and its effect on laser performance, and consider the prospects for further increase in output power and pulse energy