Semiconductor Laser Power Enhancement by Control of Gain and Power Profiles

We present theoretical calculations investigating the output power limitations of GaAs-based semiconductor lasers and the experimental results showing significant improvement of output power. To understand the influence of power limitation mechanisms, semiconductor laser with standard and unfolded cavity designs is studied. Our analysis reveals that an unfolded cavity laser enables more homogeneous longitudinal gain and intracavity optical intensity with reduced levels as compared with the standard cavity. Hence, an unfolded laser has theoretically lower power penalties induced by linear and nonlinear effects. For a 5.7-mm long laser cavity with 100-μm wide aperture, the experimental results demonstrate 21-W output from standard cavity whereas the unfolded cavity design achieves 33-W at 920 nm, which is >55% enhancement of the output, confirming the prediction of the theoretical calculations. The method represents a major step toward understanding semiconductor laser power limitations and realizing higher power output by control of longitudinal gain and power profiles.