Intensity increasing up to 4 MW/cm2 with BALB's via wavelengths coupling

摘要

An increase in the performance of micro-optic beam shaping resulted in diode laser modules with more than 400W out of 200 urn fibre based on Broad Area Laser Bars (BALB). The brightness of a 400 W laser module opened the door for new applications in material processing such as temper marking of stainless steel and metal sheet cutting. Further improvements of the light sources and the beam shaping for BALB's have increased the efficiency of the laser modules. Therefore we present an output power of 1200 W out of a 200 μm fibre (0.22 NA). This is achieved by further sophistication of the coupling technique and four wavelength coupling. The beam parameter product is still 22 mm~*mrad with a power density of 3800 kW/cm~2 if focussed to a 200 μm spot. Furthermore, each of the four wavelength modules are separately exchangeable and checkable. The availability of a top-hat profile out of the fibre proves itself to be advantageous compared to the traditional Gaussian beam profiles of fibre, solid-state and gas lasers. This leads to excellent laser cutting results with extremely small cutting kerfs down to 200 μm and very plane cutting edges. Process speeds rise up to more than 10 m/min i.e. for thin sheet stainless steel or titanium. In the near future, 600 W out of 200 μm based on BALB's with a beam compressor is possible. With wavelength coupling, power levels with up to 2 kW out of 200 μm fibre will be reached. This will result in a power density of more than 6 MW/cm~2.