Multi-kW High Brightness Yb:YAG Thin Disk Laser

Simple stable laser resonators with a single Yb:YAG thin disk module have been designed and demonstrated to produce up to 5 kW CW laser output at 1030 nm with M-2 factor of 7. Pumped with 940 nm diodes, the optical-to-optical efficiencies were >50 % at full power. Simple I and V-shaped resonators consisting of only two and three optical elements were implemented, including the 16 mm diameter Yb doped thin disk acting as an active mirror. No additional adaptive optics for aberration or mode control was used; instead the results were achieved with laser cavity designs that take into account the changing radius of curvature of the pumped thin disk. The designs ensured the laser always operated well within the stable cavity zone and with an optimised and relatively large fundamental laser mode size on the thin disk. The low optical aberrations and effective thermal management of the thin disk, mounted on a diamond cooled heat sink, together with the above cavity design approach, enabled the realization of such high power and good beam quality thin disk laser in a simple single disk laser oscillator.