A compact, reliable semiconductor laser source for materials processing, medical and pumping applications is described. This industrial laser source relies on a combination of technologies that have matured in recent years. In particular, effective means of stacking and imaging monolithic semiconductor laser arrays (bars), together with advances in the design and manufacture of the bars, have enabled the production of robust sources at market-competitive costs. Semiconductor lasers are presently the only lasers known combining an efficiency of about 50% with compact size and high reliability. Currently the maximum demonstrated output power of a 10-mm wide semiconductor laser bar exceeds the 260 W level when assembled on an actively cooled heat sink. (The rated power is in the range of 50 to 80 W with a projected lifetime of 10.000 hours) Power levels in the kW range can be reached by stacking such devices.
The requirements on the stacking technique and the optical assembly to achieve high brightness are discussed. An example of the optical setup, used in materials processing, will be shown. Spot sizes as low as 0.06 mm × 1.2 mm (FWHM) at a numerical aperture of 0.3 and output power of 500 W is achieved. This results in a power density of more than 600 kW/cm2. For increase of power wavelength coupling is used.