Design considerations for high-power GalnP/AlGalnP unstable-resonator semiconductor lasers

Simple expressions are derived to evaluate the lasing condition and power characteristics of unstableresonator semiconductor lasers (URSL's). The gain-loss characteristics of several quantum-well materials are summarized and found to be important for URSL design considerations. To optimize URSL performance, the cavity length needs to approach an optimum value, which varies from ~300 µm for an InGaAs/GaAs graded-index separate-confinement-heterostructure single-quantum-well (GRINSCHSQW) to ~1000 µm for GaInP/AlGaInP GRINSCH-SQW materials. A set of high-power (1-W, double-mirror, pulsed) 660-nm wavelength GaInP/AlGaInP URSL's with magnification of 2.5 were fabricated using focused-ion-beam micromachining technology. The brightness of a 300 µm × 1500 µm URSL approaches 320 MW cm(-2) Sr(-1) at a pump current of 3000 mA.