Abstract

The conversion of sunlight into high power laser light in space could have important applications in space manufacturing and propulsion. Thus, research on solar-pumped lasers could lead to large orbiting solar collectors concentrating sunlight on an appropriate lasant producing megawatts of cw power. Presently, most research has focused on the alkyl iodides which absorb solar light near 280 nm and then photodissociate into a radical and an excited iodine atom which lases at 1.315 μm. A number of alkyl iodides have been investigated (i-C₃F₇I, C₂F₅I, n-C₄F₉I, CF₃I) with the goal of defining the most appropriate lasant for closed-cycle low-threshold operation. A unique solar laser experiment has been constructed which has been used to evaluate these and other lasant candidates. Lasing has been achieved, using two xenon arc solar simulators, with C₂F₅I at a laser threshold of only 100 solar constants (1 SC = 1.35 kW/m²). This is the lowest threshold solar laser to date. Length of lasing, for this static gas fill system, has given important kinetic information on the recombination rate of radicals and ground state iodine atoms, an important parameter for closed-cycle operation. Studies have been completed on the scaling with pressure, solar intensity, parent molecule species, and beam shape which are leading to a fuller understanding of the alkyl iodide lasants.

© 1986 Optical Society of America