Improving side-pumping efficiency of solar-pumped lasers

Solar pumped lasers directly convert sunlight into laser radiation. In this paper, we improve the configuration and structure of the hybrid pumping cavity adding a water-cooling system in the copper cavity. Output laser power is up to 23.7 W, using an Nd:YAG crystal rod with a diameter of 8 mm and a length of 115 mm as laser media, and a 7.87% slope efficiency is achieved. A Fresnel lens with a surface of 1.03 m² is used as the primary solar light concentrator. It is shown through comparison experiments that the design of the new pumping cavity is an effective solution with a 55.92% increase in output power. We analyze the absorption loss and coupling efficiency of side-pumping light in the new cavity, and confirm that the new structure can improve the side-pumping efficiency. At the end of the article another design of composite cavity with ceramic material is put forward.