Quantum‐well lasers for direct solar photopumping

Semiconductor lasers directly photopumped by focused sunlight may be viable sources of coherent light for intersatellite communications and other low‐power spaceborne applications. In this work, we theoretically explore the possibility of realizing such devices. We specifically assess solar pumped operation of separate‐confinement‐quantum‐well heterostructure (SCQWH) lasers based on InGaAs, GaAs, and AlGaAs, as fabrication technology for these lasers is mature and they can operate at very low thresholds. We develop a model for step‐index single‐well SCQWH lasers photopumped by sunlight, examine how threshold solar photoexcitation intensities (or solar magnification requirements) depend upon material and structure parameters, design optimum structures for solar‐pumped operation, and identify design trade offs. Our results suggest that laser action should be possible in properly designed structures at readily achievable solar concentrations (10³–10⁴ suns under air‐mass‐zero conditions), and that optimum designs for solar‐pumped SCQWH lasers differ significantly from those for analogous current injection devices.