Nonlinear Dynamics in Semiconductor Lasers - Abstract
Dense spectral beam combining of broad-area semiconductor lasers is a promising technology to fabricate highly efficient direct diode lasers for material processing applications such as sheet metal cutting or remote welding. We demonstrate its industrial feasibility by our 5kW to 200Ám-fiber-coupled, external-cavity-based laser system consisting of five spectrally beam-combined modules with a lateral beam parameter product of 6 mm x mrad. Since broad-area diode lasers have the highest yet known electrical-optical conversion efficiency this concept is likely to supersede today's well established fiber and disk lasers. The system's further brightness scalability, however, is believed to be limited by the lateral beam quality degradation of the individual broad-area emitter with increasing self-heating. By means of numerical simulations in conjunction with experimental findings we show that spatially-varying and thermally-induced waveguiding is the predominant mechanism to lead to brightness deterioration at high input currents.