Power scaling limitations in quasi-three level thin gain lasers

In this paper, based on a self-consistent numerical method, the re-absorption and concentration quenching effects on Yb:YAG thin disc laser operation is simulated. These effects are evaluated taking into account the spectroscopic, population and mechanical factors dependent on the doping concentration and temperature. A photon tracing code and finite element analysis is utilized to calculate the absorbed pump density and the temperature distribution, respectively. This model shows that the optical efficiency is affected by re-absorption losses and fluorescence concentration quenching and drops at concentrations greater than 28%. It is concluded that the optimum thickness decreases exponentially with doping concentration. The temperature has most influences on the lasing action through the Boltzmann's redistribution. The predicted laser output power exceeds the actual value if the temperature and doping concentration dependency of laser parameters are neglected. Modeling results are accurately in agreement with experimental data. Through variation of laser designing parameters, power scaling laws of thin disc laser has been derived.

► Based on a self consistent numerical model, re-absorption and concentration quenching affects on lasing action are studied.
► A photon tracing code and FEA is utilized to calculate the absorbed pump and disc temperature, respectively.
► Optical efficiency starts to drop in concentrations larger than 28%, due to dominating of power scaling limitations.
► It is concluded that the optimum thickness decreases exponentially with doping concentration.
► Through this model, power scaling laws of disc laser can be derived.