Solid state lasers with phase conjugation approaching the kilowattrange

Abstract

High average output power in conjunction with high beam quality is a crucial point for future industrial applications of solid state lasers. Phase conjugation based on stimulated Brillouin scattering in multi amplifier systems results in average output powers up to the kW-range with high beam quality. A solid state laser system containing six amplifiers and a master oscillator was developed. The system consists of a parallel arrangement of two double pass amplification stages with phase conjugating mirrors. To increase the average output power, both beams are amplified in additional single pass amplifiers again and combined using a thin film polarizer. Optical systems between the amplifiers guarantee the variability of average pumping power without damage of optical components. Therefore the average output power can be tuned between 50 W and 520 W. The beam quality was measured using the moving edge method and corrected for the second momentum of the laser beam. The beam quality is 1.8 times the diffraction limit at minimum pumping power and 5.2 times the diffraction limit at 85% of maximum pumping power.