Solar-pumped lasers are being developed for the direct conversion and transmission of solar power in space. Laser radiation is appropriate for power transmission in space because of the small divergence and the short wavelength of a laser beam compared to that generated by a microwave system. Applications of laser technology include:
1- Laser power transmission from space to Earth. 2- Laser propulsion of space-borne or air-borne vehicles. 3- Laser power transmission to remote spacecraft. 4- Deep-space communications. 5- Remote-sensing. 6- Materials-processing and manufacturing.
These applications are shown in Fig. 1-13. Whilst conventional lasers powered by electrical energy could be used to transmit solar energy in space, direct solar-pumped lasers offer the advantage of eliminating the need for electrical power-generating plant. However, a laser system operating in space has a number of requirements imposed upon it including:
1- A gas or liquid-phase lasant for continuous cooling and recharging for operation at power levels greater than 1MW.
2- A high temperature operation to reduce cooling requirements.
3- A chemical reversibility to renew the lasant in space.
4- A broadband pumping to make efficient use of the available solar spectrum.