High-Brightness Unstable-Resonator Semiconductor Laser Diodes

High-power high-brightness unstable-resonator edge-emitting semiconductor laser diodes with dry-etched curved mirrors were fabricated and characterized. The epitaxial structure was optimized for high output power operation and consists of a GaAs/AlGaAs gradedindex separate-confinement heterostructure (GRINSCH) with a single 980-nm-emitting InGaAs quantum well. The curved mirrors of the unstable-resonator lasers were fabricated using an optimized chemically assisted ion-beam etching (CAIBE) process. The beam quality of the devices was evaluated by measuring the position and the size of the virtual source. Tapered designs with lateral absorber regions show continuous-wave (cw) output powers of over 1.6W having 85% of the intensity in the main lobe of the lateral virtual source. A maximum brightness of 150MW/(cmsr) was achieved in cw operation.