High-power and high-brightness solid state laser systems for precise and fast micromachining

To meet the industry's demand for reducing machine cycle lengths concerning laser-drilling a laser was developed at the LMTB-laboratories that emits high-power peak-pulses at excellent beam-quality. In co-operation with Technical University of Berlin TU Berlin) a Nd:YAG Master-Oscillator Power-Amplifier (MOPA) laser system is undergoing permanent enhancements aiming at shorter pulse duration, higher fluence and improved long-term stability. Presently, the output power of the oscillator (10W@1064nm) with a beam-quality of M-2=1.3 is amplified to more than 100W@1064nm with M-2=2.3 and a single pulse energy up to 800 mJ. The pulse duration can be varied between 31 and 230ns. On account of the excellent beam quality, frequency conversion was carried out down to 266mn. The MOPA-System was used for laser micro scribing and drilling experiments into metals and ceramics where the influence of the beam quality on the geometrical shape of the hole is investigated and compared with applications conducted with similar laser systems. Additionally means in optimizing the drilling process such as burr-minimizing and melt-reduction were introduced. Furthermore, experiments using tapered drilling technique are undertaken. A maximum aspect ratio of 1:180 in sapphire was obtained. We achieved high ablation rates and precise structures in Al2O3 (ceramic and sapphire), AlN, ZrO2, Ni-base alloy, platinum, tungsten and many more materials. Further improvement of the system was undertaken by means of multimode fibers as phase conjugate mirrors (PCM) using the effect of stimulated brillouin scattering (SBS).