Gain observation of the argon excimer at 126 nm by use of an ultrashort high intensity laser pulse propagating in a hollow fiber

In this paper we have proposed a new excitation method to demonstrate a practical Ar₂* laser using a high intensity ultrashort pulse laser. A high intensity laser produced electrons will be utilized to initiate the Ar₂* production kinetics. We have observed a nonlinear increase of the Ar₂* emission intensity at 126 nm by changing the hollow fiber length. A small signal gain of 0.05 cm^-1 was evaluated at 126 nm. Kinetic analysis revealed that the high intensity laser produced electrons via optical field ionization process actually initiated the Ar₂* production processes. This result is the first observation of the gain at 126 nm pumped by a compact device other than electron beam machine and will lead to the stimulated emission at 126 nm with a repetition rate of 10 Hz.