Computational analysis of the efficiency limit of a fully planar solar-pumped laser.

A Monte Carlo simulation code was used to predict the solar-to-laser conversion efficiency of a fully planar solar-pumped laser. The calculations, which simulated an experimental setup with a diameter of 30 cm, reproduced the experimental results with a high degree of accuracy. The current experimental configuration yielded a limited laser power of 34 mW and a slope efficiency of 0.1%, which were attributed to incomplete spectral utilization and reflection losses of the photon confinement mechanism. In this study, the impact of each factor on efficiency degradation was quantitatively demonstrated, and avenues for future improvement were identified. The findings reveal that the solar-to-laser conversion efficiency can reach 17.4% under optimal conditions, namely, the utilization of quantum dots that fluoresce at near-infrared wavelengths and ideal mirrors exhibiting perfect reflectivity over the full range of incident angles and wavelengths.