Advanced optical pump concepts for high energy lasers

Abstract

Lasers of very high energy output and good beam quality can be made using extremely intense, incoherent optical pump sources. These pump sources can be considerably brighter than the conventional xenon flashlamps used for neodymium glass and atomic iodine lasers. Intensities demonstrated for these incoherent emitters lie in the megawatts/cm2 range. The pulse power required to drive the optical pump sources can be derived from high explosives (HE) or from more conventional energy storage means. HE has been used to drive kilojoule atomic iodine lasers using two different approaches. In one the detonating HE launches a strong shockwave through argon. The shock front is a large area, blackbody radiator of temperature 25,000 K. The intense emission optically pumps the photolytic iodine medium contained in a quartz cell. In the other approach HE drives a magnetic flux-compression generator to produce current pulses in the 100-kA range. This large current is used to explode a large area metal film. The resulting plasma radiates like a blackbody with a temperature of ~20,000 K. For multiple pulse operation conventional pulse-power machines can drive various sources appropriate for high energy lasers. One of these is the surface discharge in which a large-area plasma is formed on the surface of a dielectric. These discharges among others can drive very large, multiple pulse, gas phase lasers.