SCALABLE CONCEPT FOR DIODE-PUMPED HIGH-POWER SOLID-STATE LASERS

A new, scalable concept for diode-pumped high-power solid-state lasers is presented. The basic idea of our approach is a very thin laser cry stal disc with one face mounted on a heat sink. This allows very high pump power densities without high temperature rises within the crystal . Together with a flat-top pump-beam profile this geometry leads to an almost homogeneous and one-dimensional heat flux perpendicular to the surface. This design dramatically reduces thermal distortions compare d to conventional cooling schemes and is particularly suited for quasi -three-level systems which need high pump power densities. Starting fr om the results obtained with a Ti:Sapphire-pumped Yb:YAG laser at vari ous temperatures, the design was proved by operating a diode-pumped Yb :YAG laser with an output power of 4.4 W and a maximum slope efficienc y of 68%. From these first results we predict an exctracted cw power o f 100 W at 300 K (140 W at 200 K) with high beam quality from a single longitudinally pumped Yb:YAG crystal with an active volume of 2 mm3. Compact diode-pumped solid-state lasers in the kilowatt range seem to be possible by increasing the pump-beam diameter and/or by using sever al crystal discs.