Efficiency of continuous-wave solar pumped semiconductor lasers

We report the results of an efficient solar pumped semiconductor laser system that uses high efficiency multi-junction photovoltaic cells and laser diodes in order to achieve the sunlight to laser light conversion efficiency of over 10% without any active cooling and concentration optics. Semiconductor lasers with wavelength from 445 nm to 1550 nm are powered directly by an array of photovoltaic (PV) cells under one sun illumination (100 mW/cm2). The maximum energy efficiency reaches 10.34% at 976 nm with an output power of 4.31 W. This system is inherently more efficient than direct solar pumped lasers that have been studied in the past and could play a key role in future renewable energy production and power beaming applications.