Lasers pumped by solar radiation (review)

A comparative analysis is made of various gas and solid-state lasers pumped by solar radiation. The ranges of the optimal (from the efficiency point of view) values of the following parameters are determined: the density of the active medium, cross section for absorption of solar radiation, rate of deexcitation of laser levels, transverse dimensions of the active medium, and concentration of solar radiation. It is shown that only two systems are capable of providing an efficiency which is acceptable in practice (~3–6%): a closed-cycle gasdynamic laser and a solid-state waveguide laser with transverse solar pumping. The solid-state laser is more promising and has a number of advantages such as simple construction and operation, lower (by one or two orders of magnitude) necessary concentration of solar radiation, and much smaller transverse dimensions of the active medium.