Design of a solar-pumped semiconductor laser

Since their first demonstration in 1962, solar-powered lasers have attracted interest as a tool for generating and distributing renewable energy. Proposals have ranged from orbiting solar laser power stations beaming energy down to terrestrial photovoltaic receivers, to arrays of solar lasers in desert areas linked to population centers via optical fibers. However, despite several decades of research, solar-powered lasers have yet to reach the levels of efficiency or output beam quality that would make these applications feasible. Here we propose a new solar laser architecture, the solar-pumped vertical external cavity surface emitting laser (SP-VECSEL), as a logical continuation of the proven mode-converting capabilities of diode-pumped VECSELs. In experiments using VECSEL gain samples pumped using sunlight, we demonstrate that no major drop in efficiency is observed beyond that associated with the quantum defect of the pump light, allowing us to predict that SP-VECSEL performance can substantially surpass that of existing solar lasers.