Modeling of Efficiency and Uniformity of Different Pumping Structures of Slab Lasers

Modeling for end-pumping and edged-pumping high power solid-state slab lasers. Both analytic and ray tracing methods were used to analyze the distributions of absorbed pumping power using laser-diode-array pump sources. The pumping light field profiles of the different pumping structures mentioned above are acquired, according to which the absorption power density and uniformity of the pumping light are analyzed. In order to compare the pumping uniformity and efficiency of the two pumping structures, cylinder lens are adopted for beam focus and shaping. Each cylinder lens gets different size, but coupling efficiency is about 91% as the same. The irradiance profiles of these two pumping structure are simulated via ray trace method of non-sequential component of ZEMAX software, each is confirmed finally, i.e. the absorbed pumping power density distribution is calculated. The edge-pumped and end-pumped slab lasers allow for a longer absorption path than in face-pumped slabs. However, the tradeoff made to reach higher pump efficiency is lower absorbed pump power distribution uniformity due to the long absorption path. By comparing simulation results of the different pumping structures, it was found that uniformity of absorbed pumping distribution on width-thickness plane in doped region of crystal with end-pumping structure is the best, and the absorbed peak power density is 0.0168 W/mm³ which is the highest among three pumping structures. It is more uniformity distribution for pumping light in the Z direction of crystal axis.