Influence of Initial Gas Pressure on the Spatial Intensity Distribution of Double-Pass Amplified 69.8 nm and 72.6 nm Lasers

Abstract In this study, a discharge-produced plasma was utilized as the gain medium, and a silicon carbide (SiC) mirror was employed to achieve simultaneous double-pass amplification of Ne-like Ar lasers at 69.8 nm and 72.6 nm. Notably, the double-pass amplification of the 72.6 nm Ne-like Ar laser is reported for the first time in this work. We experimentally investigate the dependence of the spatial intensity distribution of the double-pass amplified 69.8 nm and 72.6 nm lasers on the initial gas pressure. As the gas pressure increases from 14 Pa to 18 Pa, the intensity profile of the double-pass amplified laser evolves from a central-intensity-dominated distribution to an edge-enhanced annular distribution. For the double-pass amplified 69.8 nm laser, the divergence angle increases from 2.1 mrad to a peak-to-peak value of 3.5 mrad. Correspondingly, the divergence angle of the double-pass amplified 72.6 nm laser increases from 1.7 mrad to a peak-to-peak divergence angle of 3.4 mrad.