Perspective of Solar Pumping of Solid State Lasers for ESA Missions
The use of lasers for space missions has been increasing in the past and will dramatically increase in the future. Lasers in space often fulfill tasks that cannot be accomplished by other means. Examples are measuring distances of millions of kilometers with nanometer precision, detecting trace gases in the atmosphere of Earth from a satellite, or transmitting data between satellites over distances of some 10,000 km at very high rates. With the exception of semiconductor lasers, almost all of the la- sers used in space are optically pumped solid state lasers. These lasers provide higher powers and better beam quality than semiconductor lasers and are therefore indispensable. However, they rely on optical excitation which is usually provided by a large number of low-power semiconductor lasers. The semiconductor lasers in turn operate on electrical energy that is generated by solar panels. It is there- fore sensible to investigate whether direct excitation of solid state lasers with focused light from the Sun is possible. This solar pumping of solid state lasers has been thoroughly investigated in this study, with particular emphasis on its applicability to ESA missions.