A 1.1 kW CW intra-cavity frequency-doubled thin-disk laser

We report on the generation of continuous-wave, intra-cavity frequency-doubled laser radiation in a thin-disk laser with more than 1.1 kW of output power at 515 nm. The achieved overall optical efficiency in multimode operation (M2 approx. 20) was 51.6% (pumped at 969 nm) and 46.2% (pumped at 940 nm), respectively. In fundamental-mode operation, an output power of 419 W was achieved at a pumping wavelength of 969 nm, corresponding to an overall optical efficiency of 45.5%. In this latter case, the beam quality factor was measured to be M2x = 1.28 and M2y = 1.36. The wavelength stabilization and spectral narrowing as well as the polarization selection necessary for stable second-harmonic generation was achieved by the integration of a highly efficient grating waveguide mirror as cavity end-mirror.