Theroretical And Experimental Research Of Yb:YAG Thin Disk Laser

High average power diode pumped solid-state laser is the hotspot in researchand development of laser. Laser-diode pumped thin disk laser has advantages ofhigh output power and efficiency and good beam quality. Since have been proposedfor the first time in1993, LD pumped thin disk laser is an important developmentdirection, and has a broad application prospects in optical information storage, micromaterial processing, high-speed communications, biomedical and military.The design of the multi-pass structure of the LD pumped Yb:YAG thin disklaser has always been diffculty. The multi-pass pump module which is produced inthe company Dausinger+Giesen GMBH of Germany has been widely used in theworld. The module is expensive and the core technique of using parabolic mirror torealize24-passes even more passes of the pump reflection is still dominated byGermany. The four-pass pump coupling system is well designed with a pair ofrectangular prism and a focusing lens, in this pump module the absorption ofYb:YAG crystal is84%.At present, we often use indium solder to weld the Yb:YAG and the heat sink.The process of this technique is complex and the solder should have high thermalconductivity. In this article the direct cooling arrangement is put forward. The tapwater is contacted with the Yb:YAG through a V groove in the copper heat sink, thecrystal is the window of the heat sink. Then simulation the stability of the resonatorand calculate the radius of the laser spot in different position of the resonator withthe different cavity length, according to the simulation, we can choose the best cavitylength.We demonstrate a Yb:YAG thin disk laser with a novel four-pass pumpedstructure and direct water cooling device. The multi-mode pump radiation is from afiber-coupled940nm diode laser. The Yb:YAG disk with10mm diameter and500μmthickness is employed. The Yb3+atom fraction is10%. The direct coolingarrangement and the four-pass pump coupling system is put forward. We set updifferent laser cavities of the thin disk laser. With28.6W incident pump power in F-Presonator, the maximum output power of3.28W at1031nm is obtained. M2x=1.79，M2y=1.86. The optical-optical conversion efficiency is20.5%.