Effect of rotational and intramode vibrational coupling on short-pulse amplification in CO&lt;inf&gt;2&lt;/inf&gt;

R Harrach

doi:10.1109/jqe.1975.1068648

Abstract

The extraction of stored energy from a CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -laser amplifier by a short-duration input pulse is described using a rate-equation theory. The influence of rotational and intramode vibrational energy-transfer processes is studied as a function of the energy density E <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</inf> and width τ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> of the input pulse. By a suitable choice of normalized variables δ and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E_{in}/E_{sat}</tex> for the extracted-energy and input-energy density, it is found that the results for different values of τ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> are interrelated by simple translations in a δ versus <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E_{in}/E_{sat}</tex> diagram. The characteristic curves in this diagram are nearly independent of the amplifier gain factor <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\exp (\alpha_{0}L)</tex> for high-gain systems. A comparison of the theory with experimental results of Figueira et al. shows satisfactory agreement and leads to an estimate of (1.0-3.5) 10 -6 s -1 torr -1 for the rate of intra-mode vibrational-vibrational (VV) energy transfer in CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> .

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