Rare gas fluoride lasers

Abstract

In this article, the rare gas fluoride lasers are discussed in detail. There is a significant interest in these lasers because they are the most efficient visible/UV lasers to date. The dominant formation kinetics of KrF* and XeF* in both discharge and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</tex> -beam pumped lasers are presented. Because of the ionic upper level the formation processes are rapid and conditions can be chosen such that the branching ratios into the KrF* and XeF* levels from both the ionic and metastable levels are close to unity. With <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</tex> -beam pumping of these lasers, a guide magnetic field enables the deposition of > 90 percent of the beam energy into the optical volume. Discharge pumping has the potential of being more efficient than <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</tex> -beam pumping; however, the key technical issues of discharge stability and metastable production efficiency have to be addressed. Stabilization of the discharge is possible if an external source of ionization is used. The quenching of the rare gas fluorides by two- or three-body processes has been carefully measured and analyzed. The three-body quenching of KrF* leads to the eventual formation of the excited triatomic Kr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> F* which radiates in a broad band centered at 410 nm. It has also been determined that ionic and excited state absorption in the active media is large enough to impact the extraction efficiency of these lasers. In the case of KrF, the dominant absorbing species are F <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> , F-, and Kr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> F*, while Xe+ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> appears to be the dominant absorber in XeF*. Finally, we have also investigated experimentally and theoretically the effects of the vibrational relaxation in the upper level and finite lifetime of the lower level on XeF* laser performance.