Introduction

Laser materials for lamp pumping can also be used for solar pumping. Research into space solar power stations (SSPSs) has been performed to use solar energy in space. In space, solar energy is over ten times more available than on the surface of the Earth. Solar power can be directly transformed into laser radiation with high efficiency. The idea of a solar pumped laser has been studied in the US, Germany, Israel, and Russia. A Japanese technical committee for investigating the feasibility of a laser SSPS (L-SSPS) was organized by the Japan Aerospace Exploration Agency (JAXA) in 2002. We are developing the fundamental technology for solid-state lasers that use solar pumping. Improving both the conversion efficiency and the thermal effects will reduce construction costs.
Also, the energy cycle with the sunlight laser, water, and magnesium is proposed by Yabe group in Tokyo Institute of Technology.

Nd/Cr:YAG had been developed to convert a wide spectrum of sun-light to monochromatic laser light or to improve laser efficiency pumped by lamp light.