Shortly after the invention of the laser, researchers began to dream of converting sunlight into laser radiation directly. A direct conversion of concentrated solar light into a coherent laser beam improved the conversion efficiency because of the simple design of the structure, which is an innovation in the new field of solar energy utilization. We utilize the Fresnel lens of 1m2 to collect solar light, which is coupled into the conical chamber pumping Nd:YAG crystal, in 5mm-diameter 80mm-length rod. The pumping cavity is designed to combine end-pumping with side-pumping, in which the pumping light comes from many directions. It could compensate the drawbacks of single end-pumping or side-pumping. In the experiment, we obtain the maximum laser output power of 2.5 W, with a slope efficiency achieving 1.3%. By the Tracepro ray-tracing software, simulating the incoming energy distribution in the focus of the Fresnel lens, the concentration ratio of 104 is achieved.
Ideal shape of Fresnel lens for visible solar light concentration
