Time-Dependent Simulation of Thermal Lensing in High-Power Broad-Area Semiconductor Lasers

We propose a physically realistic and yet numerically applicable thermal model to account for short- and long-term self-heating within broad-area lasers. Although the temperature increase is small under pulsed operation, a waveguide that is formed within a few-nanosecond-long pulse can result in a transition from a gain-guided to an index-guided structure, leading to near and far field narrowing. Under continuous wave operation, the longitudinally varying temperature profile is obtained self-consistently. The resulting unfavorable narrowing of the near field can be successfully counteracted by etching trenches.