Short-pulse multiline and multiband energy extraction in high-pressure CO<inf>2</inf>-laser amplifiers

Abstract

The ability of a nanosecond or shorter CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -laser pulse consisting of a single vibrational-rotational transition to extract energy from an atmospheric-pressure CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> amplifier is limited owing to the finite rotational thermalization time in CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and the larger number of rotational states which share the stored energy. Theoretical studies are reported which indicate that utilizing an incident pulse consisting of several vibrational-rotational lines within the 10.6-μ band substantial improvements can be obtained over single-line extraction. Even more dramatic improvements are possible if the pulse contains vibrational-rotational transitions at both the 10.6- and 9.6-μ bands. Quantitative energy-extraction results are presented for an input Gaussian pulse consisting of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-5 10.6-\mu</tex> transitions, and for a pulse containing one line at 9.6 μ and one at 10.6 μ, traversing a 1-m amplifier, for a wide range of input energies, pulsewidths, and gas pressures. Possibilities of using multiband techniques for pulse shaping are also discussed.