Pre-pulse energy suppression for high-energy ultrashort pulses by liquid jet based plasma mirrors

Currently, the peak intensity that can be achieved in the laser focus, with intensities in excess of 1021 Wcm$^{-2}$ creates pre-pulse problem. The most successful way to eliminate pre-pulse is to use plasma mirrors. Plasma mirror contrast enhancement at relativistic intensities has been demonstrated by using pulses in the high contrast plasma mirror (HCPM) with a solid target (anti-reflection coated optics). However, every single shot requires high-quality optical surfaces. Therefore, the plasma mirror must be replaced and aligned before each shot. To overcome the issue, a liquid-based concept is attempted, and experiments are performed on the high repetition rated (500 Hz) Lambda Cubed laser (duration 30 fs). A continuously flowing fluid jet can be used as an optically flat surface that regenerates itself in less than a millisecond, which makes it possible to use high repetition rate laser pulse systems.