Vacuum ultraviolet argon excimer production by use of an ultrashort-pulse high-intensity laser

Abstract

We report on the observation of ${\mathrm{Ar}}_{2}^{*}$ emission at 126 nm by use of a hollow fiber to guide the high-intensity laser propagation in high-pressure Ar. A small-signal gain coefficient of $0.05{\mathrm{cm}}^{\ensuremath{-}1}$ was measured at 126 nm by this method. The increase of the ${\mathrm{Ar}}_{2}^{*}$ emission intensity was measured to be $\mathrm{exp}(2.5),$ with an increase of the fiber length up to 50 cm. Kinetic analysis revealed that the ${\mathrm{Ar}}_{2}^{*}$ production processes were initiated by the electrons produced by the high-intensity laser through an optical-field-induced ionization (OFI) process. A rapid conductive cooling of the OFI electrons is favorable to initiate the ${\mathrm{Ar}}_{2}^{*}$ formation kinetics more efficiently. This high-density cold plasma production method should be applicable for other vacuum ultraviolet rare-gas excimer lasers.